Ahmet is available for hire
Hire AhmetAhmet Karakaya
Verified Expert in Engineering
Java Software Developer
Istanbul, Turkey
Toptal member since July 2, 2021
Bio
Ahmet is a software engineering architect and team lead with deep expertise in communication technologies. He is highly proficient in Java, Python, TypeScript, and distributed systems tools like Kafka, Cassandra, and Redis. Ahmet specializes in solving complex challenges in distributed systems, including achieving linear scalability, optimizing performance utilization, and mastering concurrency.
Portfolio
ApiSec
Amazon S3 (AWS S3), AWS Step Functions, Amazon Simple Queue Service (SQS)...
Carrier - Residential - Mobile Apps Product Management
Cloud Architecture, Kubernetes, Apache Kafka, Python, Distributed Systems...
Integrated Bind LLC
Java, Apache Kafka, Spring Boot, Confluent, API Architecture, Refactoring
Experience
- Java - 19 years
- Software Development - 19 years
- Performance - 13 years
- Spring Boot - 12 years
- Redis - 10 years
- Apache Kafka - 10 years
- Python - 4 years
- TypeScript - 4 years
Work Experience
Back-end Engineer
2025 - 2026
ApiSec
- Designed and implemented a scalable, time-series-based reporting system built on an event-driven architecture. The solution processes and aggregates large volumes of events in near real time.
- Used AWS services including SQS, SNS, DynamoDB, Step Functions, and API Gateway. The reporting platform provides efficient storage, aggregation, and retrieval of historical metrics while maintaining high scalability, reliability, and performance.
- Created several backfill Python scripts to prepare the new data by aggregating the current event history. It maps raw event data into a new analytic data format.
- Ensured customers could display aggregated counts for selected month, business unit, and team, covering the total number of onboarded applications, discovered endpoints, executed security scans, and unresolved vulnerabilities across all endpoints.
- Built an emailing system to allow customers to receive registration and reporting content over Amazon Simple Email Service (SES).
- Built integration to manage Azure DevOps for PATs and the organization.
- Implemented a report generation system on top of the subscription platform. Generated ISO, PCI, HIPAA, FedRamp, dev, and pentest reports automatically.
Technologies: Amazon S3 (AWS S3), AWS Step Functions, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), Python 3, Java, Microservices, Micronaut, Amazon DynamoDB, APIs, REST APIs, Security, PCI DSS, FedRAMP, HIPAA, OpenAPI, Amazon CloudWatch, Cursor AI, AWS Cloud Development Kit (CDK), Python, Role-based Access Control (RBAC), gRPC, On-premise, Agentic Coding, Claude Code, Performance Improvement, Refactoring, Domain-driven Development, RDBMS
Team Lead
2025 - 2025
Carrier - Residential - Mobile Apps Product Management
- Designed and implemented the integration between Carrier’s connected HVAC systems and EnergyHub’s distributed energy resource management platform.
- Enabled Carrier smart thermostats and HVAC units to participate in utility demand response programs and virtual power plants, unlocking new revenue streams and enhancing grid flexibility.
- Led a team to integrate APIs for device control. Planned onboarding and offboarding processes.
- Supported the back-end and mobile application development team by resolving issues and enhancing APIs used in the application.
- Led Agile ceremonies, including daily stand-ups, sprint planning, sprint reviews, and demos, to ensure smooth project execution.
- Managed APIs integrations with Alarm.com, EnergyHub (Ehub), Leap. Analyzed customer needs and made a design plan, and managed the team during implementation.
Technologies: Cloud Architecture, Kubernetes, Apache Kafka, Python, Distributed Systems, Node.js, Grafana k6, NestJS, TimescaleDB, Argo CD, RESTFul APIs, REST APIs, API Integration, API Design, BullMQ, Cursor AI, Claude, Amazon Web Services (AWS), MQTT, Technical Project Management, Open Automated Demand Response (OpenADR), API Testing, API Architecture, Role-based Access Control (RBAC), gRPC, Telemetry, Real-time Data, RDBMS
Kafka Java Expert
2025 - 2025
Integrated Bind LLC
- Reviewed and modified Java Kafka settings in YAML for Java 17 compatibility.
- Ensured the existing code is reliable and made necessary improvements. Listed improved points.
- Conducted a careful upgrade of Kafka configurations, ensuring minimal disruptions.
- Provided expert insights on improving our current Kafka setup on Confluent.
Technologies: Java, Apache Kafka, Spring Boot, Confluent, API Architecture, Refactoring
Team Lead
2023 - 2025
Ayoba
- Created the superApp platform running on AWS, which includes messaging, content, games, music, payment, and advertisement.
- Architected robust back-end systems, ensuring scalability and reliability.
- Led end-to-end mobile development, spearheading the design and deployment of high-performance Android and iOS applications with a focus on scalability, user experience, and platform-specific optimization.
- Tackled complex technical challenges and fostered a culture of continuous learning.
- Analyzed app usage by leveraging tools such as Firebase and BigQuery to get a better understanding of the benefits of the features.
- Understood the client's needs and provided technical guidance. Ensured clear and effective communication between the development team and the client.
- Collaborated with the team to define and implement the technical strategy for the microservices project, including selecting the right tools and technologies.
- Worked with the architects and developers to drive the design and implementation of the microservices architecture, with a strong emphasis on modularity, scalability, and maintainability.
- Utilized AWS services for serverless computing, ensuring optimal deployment and management of functions within our microservices.
- Organized and participated in code review sessions to foster collaboration.
Technologies: Node.js, NestJS, Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS), Java, TypeScript, TypeORM, APIs, Firebase, Google AdMob, XMPP, Google BigQuery, AWS Lambda, Datadog, Crashlytics, Software Development, Slack, Performance, Redis, NoSQL, WebRTC, Agile Software Development, Leadership, Payment APIs, REST, Load Testing, Git, Microservices, Twilio, Amazon Web Services (AWS), Interviewing, Single Sign-on (SSO), CTO, Back-end Development, OWASP Top 10, Video Streaming, SQL, Scalable Application, Startups, ElastiCache, Lambda Functions, Amazon ElastiCache, Django, Security, Technical Leadership, Chatbots, Team Leadership, Telecommunications, Large-scale Projects, AdMob, Architecture, Figma, RESTFul APIs, JSON Web Tokens (JWT), Cloud, Google Ads, Google Analytics, BigQuery, Amazon Cognito, Apache JMeter, Payment Gateways, Engineering Management, System Integration, API Testing, API Architecture, API Design, Role-based Access Control (RBAC), System Architecture, Performance Improvement, Performance Optimization, Refactoring, Network Protocols, Domain-driven Development, CQRS, Fractional CTO, Real-time Data, RDBMS
Java Developer
2024 - 2024
Redwood Capital Management LLC
- Designed, developed, and maintained high-performance back-end systems and APIs to support our trading platform from scratch.
- Created an application that connects to Kalshi and Polymarket over WebSocket, handling a large number of events streaming into it. It's designed to manage high traffic efficiently using multithreading.
- Ensured application performance and scalability to handle increasing trading volumes. Conducted troubleshooting and debugged applications to enhance functionality and performance.
- Built an application that produced MBO, MBP1, and MBP10, as well as trade-formatted data, and published it over the UDP channel using ZeroMQ.
- Investigated a FIX protocol as well. It's not implemented yet.
- Set up an infrastructure on AWS, with the application running on EC2 instances and feeding MBO and MBP-1 format data into Kinesis. For security, AWS Secrets Manager is utilized, and IAM roles with security group settings are properly configured.
- Implemented the main application in Java 21, with additional modules developed in Python 3.12, including the Kalshi market downloader, data feeder for Kinesis, and Polymarket downloader.
- Created an application that integrates with the APIs of Kalshi and Polymarket for authentication, token management, and retrieving markets and subscriptions. For more details, refer to https://kalshi.com/api, https://docs.polymarket.com/.
- Wrote clean, maintainable, and efficient code while adhering to industry best practices.
Technologies: Java, PostgreSQL, Redis, Networking, UDP, Concurrent Computing, Big Data, Aeron, High-frequency Trading (HFT), FIX Protocol, Python 3, Amazon Kinesis, Amazon EC2, AWS IAM, Security Groups, WebSockets, REST, APIs, JUnit, Mockito, Unit Testing, ZeroMQ, Technical Architecture, Trading Systems, Trading, Asyncio, Multiprocessing, Amazon CloudWatch, Event-driven Design (EDD), Software Development, Git, Amazon Web Services (AWS), SQL, Performance, Protobuf, API Testing, API Architecture, API Design, System Architecture, Real-time Data, RDBMS
Senior Full-stack Architect Developer
2024 - 2024
Yaacov Silberman
- Designed the Session Initiation Protocol (SIP) platform and proposed alternative solutions.
- Investigated and recommended SIP/WebRTC devices specific to kids.
- Discussed business discussions collaborating with the client, an entrepreneur.
Technologies: Architecture, VoIP, Session Initiation Protocol (SIP), Peer-to-peer Networking, VoIP Administration, Full-stack Development, Amazon Web Services (AWS), Google Cloud Platform (GCP), Azure, Advisory, Process Development, Engineering, Spring MVC, Networking, Technical Architecture, Software Development, Git, API Testing, API Architecture, API Design
Senior Full-stack Java Developer
2022 - 2023
MUFG Investor Services - Main
- Provided solutions for the investment industry on a global scale. They offer a range of services, from middle-office outsourcing to custody, fund administration, foreign exchange, and others.
- Developed features and fixed bugs for a finance web application tool. Used PrimeNG and Angular 12. Built unit tests for each change using Jasmine and Karma.
- Created features and fixed bugs on many Java 11 microservices. Developed unit and integration tests.
- Created and edited unit and IT test cases, fully complying with scenarios.
- Made new back-end functionalities and services. Also created a UI with Angular.
- Resynced an Angular project using its forked version. Created the GitLab rebase branch from a forked repository, using the rebase branch as an upstream on the other project, and managed a huge code propagation.
Technologies: Java, Spring Boot, Angular, SSL, Oracle, Amazon Web Services (AWS), ActiveMQ, Docker, Full-stack, JavaScript, CSS, HTML, REST, Postman, Code Review, Back-end, CI/CD Pipelines, TypeScript, GitHub, Test-driven Development (TDD), Finance, Java EE (Jakarta EE), Serverless Architecture, Containers, Event-driven Architecture, Event-driven Programming, APIs, Back-end Development, Spring Microservice, Back-end Architecture, Spring, MQTT, HTTP REST, Full-stack Development, JavaScript MVC, Engineering, Cloud Architecture, Spring MVC, Swagger, Integration Testing, JUnit, Mockito, Unit Testing, Continuous Delivery (CD), Scrum, Spring Security, Amazon CloudWatch, Event-driven Design (EDD), Enterprise, Software Development, Git, Microservices, SQL, RESTFul APIs, JSON Web Tokens (JWT), Fintech, Cloud, System Integration, Financial Systems, API Testing, API Architecture, API Design, Role-based Access Control (RBAC), RDBMS
Back-end Developer
2021 - 2022
PhysIQ, Inc.
- Developed plugins and tools with Python and Kotlin on this platform.
- Created CI/CD pipelines on GitLab and created scripts.
- Performed load testing and analyzed the results with the back-end team, identifying improvement points and ensuring the system's actual capacity.
Technologies: Python, Kotlin, Java, Gherkin, Automated Testing, Kubernetes, Google Cloud Platform (GCP), Apache Kafka, Docker, Performance, REST, Load Testing, High-load, Postman, Microservices, Back-end, CI/CD Pipelines, Test-driven Development (TDD), Serverless Architecture, Containers, Event-driven Architecture, Event-driven Programming, Back-end Development, Back-end Architecture, HTTP REST, Data Engineering, ETL, Engineering, Cloud Architecture, Apache Cassandra, Spring MVC, Large-scale Distributed Systems, Swagger, Integration Testing, JUnit, Unit Testing, Continuous Delivery (CD), Multiprocessing, Event-driven Design (EDD), Software Development, Git, SQL, Scalable Application, RESTFul APIs, JSON Web Tokens (JWT), Cloud, Selenium, API Testing, API Architecture, API Design, Role-based Access Control (RBAC), Performance Improvement, Performance Optimization, Testing, Real-time Data, RDBMS
Team Lead
2020 - 2022
Turkcell Technology
- Led the team at the design, implementation, and deployment phases to meet customer expectations for a secure and seamless video conferencing solution. It is a WebRTC-based solution.
- Assisted with program and project management, along with customer requirement analysis.
- Managed domestic and foreign team members working remotely, following agile development practices.
- Built a team with new hire interviews. Attended technical sessions to improve team talents.
- Investigated open-source solutions and prepared MVP products for demonstration purposes.
- Attended code review and technical discussion meetings to share experiences.
- Designed and implemented REST APIs to integrate with third parties, which had their own business logic and wanted to incorporate a video conferencing solution.
Technologies: Java, Spring Boot, WebRTC, Kong, Agile Software Development, Apache Kafka, Redis, NoSQL, Swagger, JVM, Red Hat OpenShift, Architecture, Technical Leadership, Microservices Architecture, OAuth 2, Apache Maven, Leadership, Linux, APIs, IntelliJ IDEA, Performance, Git, Grafana, Kotlin, API Integration, Containerization, Back-end, Single Sign-on (SSO), Docker, Load Testing, Spring, SQL, Apache Tomcat, Postman, Microservices, Kafka Streams, Code Review, Jira, Bitbucket, Hibernate, Pull Requests, REST APIs, Databases, JPA, Message Queues, SOLID Principles, API Development, CI/CD Pipelines, SOAP, Team Leadership, Agile, Twilio API, Technical Hiring, Interviewing, Integration, Spring 5, Prometheus, XMPP, WebSockets, CRM APIs, Jenkins, Software Design, Task Analysis, SSL, Software Architecture, JDBC, Apache Avro, TypeScript, Amazon DynamoDB, Relational Databases, Object-oriented Programming (OOP), Continuous Integration (CI), PostgreSQL, Telecommunications, REST, High-load, AWS Lambda, Amazon RDS, API Gateways, Multitenancy, Java EE (Jakarta EE), WebLogic, Firebase, Serverless Architecture, Containers, Event-driven Architecture, Event-driven Programming, CTO, Back-end Development, Node.js, Back-end Architecture, Amazon Aurora, HTTP REST, Session Initiation Protocol (SIP), Messaging, Live Chat, Scrum Master, Video Calling, Redis Cache, Stream Processing, Advisory, Scalability, Process Development, Agile Project Management, Engineering, Cloud Architecture, Apache Cassandra, Large-scale Projects, Spring MVC, Large-scale Distributed Systems, OpenAPI, Integration Testing, Concurrent Computing, Networking, UDP, Big Data, VoIP, Unit Testing, Continuous Delivery (CD), Technical Architecture, Team Mentoring, Scrum, Spring Security, Lua, Multiprocessing, Amazon CloudWatch, Event-driven Design (EDD), Enterprise, OWASP Top 10, OWASP, Software Development, Payment APIs, Scalable Application, Security, Chatbots, RESTFul APIs, JSON Web Tokens (JWT), Payment Gateways, Red Hat Linux, Engineering Management, Jitsi, Jitsi Videobridge, API Testing, API Architecture, API Design, Zoom, SQL Server, Memory Leaks, On-premise, System Architecture, Performance Improvement, Performance Optimization, Refactoring, Network Protocols, Fractional CTO, Real-time Data, RDBMS
Team Lead
2019 - 2020
Turkcell Technology
- Managed the instant messaging platform VoIP and services development team in charge of value-added services, chatbots, location-based campaign services, payment features, sending money over the messaging application, and VoIP services.
- Led the team in the design, implementation, and deployment phases to meet customer expectations.
- Built a team with new hire interviews. Attended technical sessions to improve the team's technical expertise.
- Investigated Grafana metrics to find improvement sections for the modules in production. Shared updates with the team and organized and led technical discussions.
- Deployed media servers over AWS EC2 instances. Subscribers get a better experience by using the closest servers.
- Designed and implemented REST APIs to integrate with third parties that had their proper business logic and wanted to incorporate a messaging system.
Technologies: Java, Spring Boot, Apache Kafka, Redis, MongoDB, PostgreSQL, VoIP, SIP, Grafana, Amazon EC2, Architecture, Technical Leadership, Microservices Architecture, Apache Maven, Leadership, Linux, APIs, IntelliJ IDEA, Performance, Git, API Integration, Containerization, Back-end, Docker, Load Testing, Spring, SQL, Apache Tomcat, Postman, Microservices, Kafka Streams, Code Review, Jira, Bitbucket, Hibernate, Pull Requests, REST APIs, Databases, JPA, Message Queues, SOLID Principles, API Development, CI/CD Pipelines, SOAP, Team Leadership, Agile, Twilio, Amazon Web Services (AWS), Technical Hiring, Interviewing, Integration, Spring 5, APNs, Prometheus, XMPP, WebSockets, CRM APIs, Full-stack, Software Design, Data Processing, Low Latency, Task Analysis, SSL, Software Architecture, JDBC, Apache Avro, TypeScript, Amazon DynamoDB, Relational Databases, Object-oriented Programming (OOP), Continuous Integration (CI), Telecommunications, REST, High-load, API Gateways, Multitenancy, Java EE (Jakarta EE), WebLogic, Firebase, Serverless Architecture, AWS Lambda, Event-driven Architecture, Event-driven Programming, CTO, Back-end Development, Chatbots, Back-end Architecture, HTTP REST, Cryptography, Messaging, Live Chat, Scrum Master, Video Calling, Redis Cache, API Platforms, Stream Processing, Advisory, Scalability, Process Development, Agile Project Management, Engineering, Cloud Architecture, Apache Cassandra, Large-scale Projects, Spring MVC, Large-scale Distributed Systems, Swagger, OpenAPI, Integration Testing, Concurrent Computing, Networking, UDP, Big Data, Continuous Delivery (CD), Technical Architecture, Team Mentoring, Scrum, Spring Security, Multiprocessing, Event-driven Design (EDD), Enterprise, OWASP Top 10, OWASP, WebRTC, Software Development, Agile Software Development, Video Streaming, Scalable Application, Security, RESTFul APIs, JSON Web Tokens (JWT), Mixpanel, Payment Gateways, Red Hat Linux, Engineering Management, System Integration, API Architecture, API Design, SQL Server, Memory Leaks, On-premise, System Architecture, Performance Improvement, Performance Optimization, Refactoring, Network Protocols, Real-time Data, RDBMS
Software Architect
2017 - 2019
Turkcell Technology
- Designed a highly scalable messaging application server.
- Migrated the project from the Oracle RDBMS to the Apache Cassandra NoSQL database.
- Coded and designed a push notification server for Apple and Android devices, handling approximately 100,000 TPS notifications.
- Delivered a solution for usual problems in distributed systems, such as linear scalability, performance utilization, and concurrency.
- Installed an OpenStack Object Storage server and programmed a client's access, attending a design intent meeting with the engineer from Red Hat.
- Selected the best technology stack to ensure the application would handle large amounts of traffic quickly and without issues.
Technologies: Java, Spring Boot, Apache Kafka, Redis, Cassandra, Coherence, Apache JMeter, OpenStack Swift, Angular, NoSQL, Flink, Distributed Systems, Architecture, Technical Leadership, Microservices Architecture, Apache Maven, Leadership, Linux, APIs, Python, IntelliJ IDEA, Performance, Git, Grafana, Back-end, JavaScript, Docker, Spring, SQL, Apache Tomcat, Postman, Microservices, Kafka Streams, Code Review, Jira, Bitbucket, Hibernate, Pull Requests, REST APIs, Databases, JPA, Message Queues, SOLID Principles, SQL Stored Procedures, Akka, API Development, CI/CD Pipelines, SOAP, Team Leadership, Agile, Integration, Spring 5, APNs, Prometheus, XMPP, WebSockets, CRM APIs, Full-stack, Software Design, Data Processing, Low Latency, Task Analysis, SSL, Software Architecture, JDBC, Apache Avro, Amazon DynamoDB, Relational Databases, Object-oriented Programming (OOP), Continuous Integration (CI), PostgreSQL, Telecommunications, REST, High-load, API Gateways, Multitenancy, Java EE (Jakarta EE), WebLogic, Firebase, Serverless Architecture, AWS Lambda, Event-driven Architecture, Event-driven Programming, Back-end Development, Chatbots, Back-end Architecture, HTTP REST, Cryptography, Messaging, Live Chat, Redis Cache, API Platforms, Stream Processing, Scalability, Agile Project Management, Engineering, Apache Cassandra, Large-scale Projects, Spring MVC, Data Migration, Large-scale Distributed Systems, Java Servlets, Swagger, OpenAPI, Concurrent Computing, Networking, UDP, Big Data, VoIP, Unit Testing, Continuous Delivery (CD), Technical Architecture, Scrum, Spring Security, Multiprocessing, Event-driven Design (EDD), Enterprise, OWASP Top 10, OWASP, Software Development, Scalable Application, Security, RESTFul APIs, JSON Web Tokens (JWT), Mixpanel, JAX-WS, Red Hat Linux, System Integration, API Architecture, API Design, SQL Server, Memory Leaks, On-premise, System Architecture, Performance Improvement, Performance Optimization, Refactoring, Network Protocols, Real-time Data, RDBMS
Senior Software Developer
2014 - 2017
Turkcell Technology
- Developed a registration server for a messaging application, providing the new generation with instant messaging, voice, and video-call experience.
- Used custom, internally developed simulator tools and common ones such as JMeter for load testing.
- Monitored, analyzed, and tuned distributed memory usage.
Technologies: Java, Spring Boot, Apache Kafka, Redis, Cassandra, PostgreSQL, Oracle, Architecture, Microservices Architecture, Apache Maven, Linux, APIs, Python, IntelliJ IDEA, Performance, Git, Grafana, Back-end, Spring, SQL, Apache Tomcat, Postman, Kafka Streams, Code Review, Jira, Bitbucket, Hibernate, Pull Requests, REST APIs, Databases, JPA, Message Queues, SOLID Principles, SQL Stored Procedures, Akka, API Development, SOAP, Spring 5, APNs, Prometheus, XMPP, WebSockets, Software Design, Data Processing, Low Latency, SSL, Software Architecture, JDBC, CSS, Relational Databases, Object-oriented Programming (OOP), Continuous Integration (CI), Telecommunications, REST, High-load, Multitenancy, Java EE (Jakarta EE), WebLogic, Firebase, Serverless Architecture, Back-end Development, Chatbots, Back-end Architecture, HTTP REST, Data Engineering, ETL, Cryptography, Messaging, Live Chat, Redis Cache, API Platforms, Stream Processing, Scalability, Engineering, Apache Cassandra, Large-scale Projects, Spring MVC, Large-scale Distributed Systems, Java Servlets, Swagger, OpenAPI, Concurrent Computing, Networking, UDP, Big Data, VoIP, Spring Security, Event-driven Design (EDD), Enterprise, OWASP Top 10, OWASP, Software Development, Security, RESTFul APIs, JSON Web Tokens (JWT), Mixpanel, JAX-WS, Red Hat Linux, System Integration, API Architecture, SQL Server, Memory Leaks, On-premise, System Architecture, Performance Improvement, Performance Optimization, Refactoring, Network Protocols, Real-time Data, RDBMS
Senior Software Developer
2010 - 2014
Nortel Netaş
- Developed A2, Nortel's VoIP solution implemented and currently maintained by foreign and Turkish engineers. It included over 40,000 Java classes and C codes.
- Handled the base architecture, including multithreading, JVM performance issues, traffic, and overload conditions.
- Collaborated with Genband's engineers, formerly Nortel, to implement new features and solve problems.
- Designed and developed telecommunications and enterprise projects using Java technologies.
- Developed a UDM project that is a device-change event dispatching system. Built an alarm management system for a secure XML gateway that provides web services from any endpoint and implemented a bulk SMS sender system for enterprise customers.
- Attended conference calls with product line management, design architects, technical support engineers, and managers to develop the best solutions for customers' needs.
Technologies: Java, Spring Boot, JVM, Performance, Distributed Systems, Multithreading, VoIP, SIP, Oracle, Apache Maven, Linux, IntelliJ IDEA, Back-end, Spring, SQL, Code Review, Jira, Pull Requests, REST APIs, Databases, Message Queues, SOLID Principles, SOAP, Spring 5, Software Design, Low Latency, JDBC, CSS, Relational Databases, Object-oriented Programming (OOP), Telecommunications, REST, High-load, Java EE (Jakarta EE), WebLogic, Back-end Development, Back-end Architecture, HTTP REST, Session Initiation Protocol (SIP), API Platforms, Engineering, Large-scale Projects, Java Servlets, Swagger, Concurrent Computing, Networking, UDP, Big Data, Multiprocessing, Enterprise, C++, Software Development, JAX-WS, Red Hat Linux, Apache Struts, System Integration, SQL Server, Memory Leaks, System Architecture, Performance Improvement, Performance Optimization, Network Protocols, RDBMS
Software Development Support
2006 - 2009
Nortel Netaş
- Collaborated with Nortel's customers, AT&T and T-Mobile.
- Identified and solved software, hardware, configuration, and signaling issues on GSM and UMTS systems.
- Prepared documentation with solutions to be used for similar issues.
Technologies: C, Java, MySQL, Linux, IntelliJ IDEA, Back-end, Software Design, Telecommunications, Java EE (Jakarta EE), WebLogic, Networking, UDP, VoIP, Enterprise, SQL Server, Network Protocols, Real-time Data
Project History
Messaging Platform
https://bip.com/en/The project is a server-side BiP messaging application that I designed and developed. It gave the new generation an instant messaging, voice, and video-call experience. This platform has millions of users from over 100 countries and can scale linearly.
I worked on this project as a software developer, architect, and team lead.
I worked on this project as a software developer, architect, and team lead.
Conference Solution
I designed and developed a multi-tenancy conference solution from scratch, leading a team in the design, implementation, and deployment phases to meet customer expectations. I also delivered program and project management and analyzed customer requirements. There were team-building stages and technical interviews that I participated in.
This product comprises many modules, including API interfaces and third-party solutions to manage meetings programmatically. Companies can use the same infrastructure with a private web address and specify user names on a screen. Third-party providers and individuals can view the meeting reports they participated in.
I also completed the payment system integration, allowing customers to buy a private meeting ID via credit card or mobile payment methods.
This product comprises many modules, including API interfaces and third-party solutions to manage meetings programmatically. Companies can use the same infrastructure with a private web address and specify user names on a screen. Third-party providers and individuals can view the meeting reports they participated in.
I also completed the payment system integration, allowing customers to buy a private meeting ID via credit card or mobile payment methods.
Mobile Device Management System
The UDM project is a device-change event dispatching system used by GSM operators to track SIM cards and mobile phone changes. I was the development phase leader, overseeing customer meetings and delivering the tools aligned with the most appropriate technologies.
Bulk SMS Platform
A bulk SMS platform project used by GSM operators to send SMS messages. I've contributed to the project as the software development phase leader. The project required high performance in load testing for platform improvement.
Nortel VoIP Platform
http://netas.com.tr/A2 is Nortel's VoIP solution, currently maintained by foreign and Turkish engineers, including over 40,000 Java classes and C codes.
I collaborated with Genband's engineers to implement new features and solve related problems while handling the base architecture, including multithreading, JVM performance issues, traffic, and overload conditions.
I collaborated with Genband's engineers to implement new features and solve related problems while handling the base architecture, including multithreading, JVM performance issues, traffic, and overload conditions.
XML Gateway
The Public Integration Box project is a highly secure device and active working redundancy system that provides web services and monitors data over VPN. It consists of IPSEC VPN, a firewall, IDS/IPS, and load balancer components.
I worked on this project as a software development phase leader.
I worked on this project as a software development phase leader.
Health Tourism System
A platform that I've designed in collaboration with a teammate to facilitate the appropriate doctor and hospital arrangements for patients coming from abroad. Access to the system is possible via web and mobile terminals, and users are informed of updates via notifications.
Remote Patient Monitoring System
I designed and implemented load test tools in Kotlin and Python. I also created test plans, reports, and scenarios for testing project requirements to ensure the overall quality of the delivered software. Additionally, I worked on the relationship traceability between requirements and test cases, contributing to and assisting in improving test methods and strategies. I also communicated findings to both technical and non-technical audiences.
Automatic Prepaid Payment System
Automatic control of a prepaid payment system used as a tool between prepaid payment firms and operators. The system connects to the web pages of different telecom operators, then scraps and fills form posts automatically from the web page.
Push Notification Platform
The push notification platform was designed and implemented to reach offline users. It applied microservices and async communication paradigms, and the system could scale quickly and linearly. Some platform features include:
• GCM and Firebase Cloud Messaging (FCM) XMPP Connection Server
• APNS TCP and HTTP/2 connection
• Java, Spring Boot, and Kafka
• Message throttling
• Parallel programming
• Grafana and Prometheus
• GCM and Firebase Cloud Messaging (FCM) XMPP Connection Server
• APNS TCP and HTTP/2 connection
• Java, Spring Boot, and Kafka
• Message throttling
• Parallel programming
• Grafana and Prometheus
BiP Web GUI
https://web.bip.comThe BiP Web UI is one of the terminals, such as mobile and desktop apps. The project involved designing and implementing the web UI parallel work with users' mobile devices and handling the WebSocket connection. I also used Angular as a web framework.
BiP Discover Management Console
A corporate customer administrator panel with diverse functionalities, including a super admin that can create and activate new corporate customers. It was a full-stack project that used Angular as a web framework. I also handled role management and the customer management portal.
Database Migration Project
A database migration project of millions of users' roster data from RDBMS to NoSQL on the fly, without any service interruption. It involved redesigning the tables in terms of needs for the NoSQL tech stack and coding a scala job to retrieve data in RDBMS and then create it in SSTable format.
Reconciliation Application
I implemented solutions for the investment industry on a global scale. They offer a range of services, from middle-office outsourcing to custody, fund administration, foreign exchange, and others.
I created new back-end functionalities and services. I also implemented back-end services in terms of the microservices concept. ActiveMQ and FeignClient were used for intercommunication, and the UI was created using Angular 12. For identity services, Keycloak was used to create users and services with a range of roles.
I created new back-end functionalities and services. I also implemented back-end services in terms of the microservices concept. ActiveMQ and FeignClient were used for intercommunication, and the UI was created using Angular 12. For identity services, Keycloak was used to create users and services with a range of roles.
Chatbot Platform Similar to WhatsApp Business
I created a chatbot platform with functionalities similar to WhatsApp Business.
FEATURES
• Third parties can consume APIs.
• Security flows are designed to include JWT roles, HMAC, and initial registration.
• A linearly scalable platform handling high messaging throughput.
FEATURES
• Third parties can consume APIs.
• Security flows are designed to include JWT roles, HMAC, and initial registration.
• A linearly scalable platform handling high messaging throughput.
Trading Tool | Kalshi, Polymarket, Fix
The project involves rebuilding existing software to ensure its long-term usability and connecting to multiple market feeds to create order books. The current system uses Python for data parts with databases, including PostgreSQL. The application was designed and implemented from scratch by using the Java programming language. The application connects to Kalshi and Polymarket platforms over a WebSocket to retrieve the real-time events, which are processed in five milliseconds in the application. Then, it is published over the UDP channel to the network (Aeron). I also implemented several environmental projects to retrieve the marks and assets from the corresponding system and store them in databases periodically. The platform works on AWS.
Reward System on the Super App
Rewards are offered through various campaigns in an ongoing effort to increase user engagement, revenue, and partnership within the Ayoba ecosystem. For example, in the chat and win campaign, users are rewarded with Ayoba coins, vouchers, and data or airtime.
I led and implemented the project, which included the following modules: rule engine, event queue, Firebase integration, Netmera client-side events, and reward queue with Amazon SQS. The reward listener writes an entry into the audit table for reconciliation purposes and the reporting database for operating company reporting.
I led and implemented the project, which included the following modules: rule engine, event queue, Firebase integration, Netmera client-side events, and reward queue with Amazon SQS. The reward listener writes an entry into the audit table for reconciliation purposes and the reporting database for operating company reporting.
Payment Integration on the Super App
I was involved in integrating Ozow and Peach payment services into the super app, allowing users to pay and send money. I implemented back-end services and followed client development for the electronic fund transfer and credit card modules.
Super App & Messaging Platform
This platform is an all-in-one app where users can chat, call, share, play, listen, watch, and more. I was involved in the super app's implementation, including messaging, rewards, campaigns, content, and advertisements.
I led and mentored a team of developers, ensuring they were well-coordinated, motivated, and productive. I also facilitated a collaborative and innovative work environment. I understood the client's needs, provided technical guidance, and effectively communicated requirements with the development team.
In collaboration with my team, we defined and implemented the technical strategy for the microservices project, including selecting the right tools and technologies. I worked with the architects to drive the design and implementation of the microservices architecture, focusing strongly on modularity, scalability, and maintainability. We leveraged AWS services for serverless computing, ensuring optimal deployment and management of functions within our microservices.
I led and mentored a team of developers, ensuring they were well-coordinated, motivated, and productive. I also facilitated a collaborative and innovative work environment. I understood the client's needs, provided technical guidance, and effectively communicated requirements with the development team.
In collaboration with my team, we defined and implemented the technical strategy for the microservices project, including selecting the right tools and technologies. I worked with the architects to drive the design and implementation of the microservices architecture, focusing strongly on modularity, scalability, and maintainability. We leveraged AWS services for serverless computing, ensuring optimal deployment and management of functions within our microservices.
Digital Trade Tool for On-site Marketing
Digital Trade Tool is used by agencies to promote applications through on-site marketing. I led a team in developing the following modules:
• Agencies login/admin
• Campaigns management
• Agent event report
• Event detailed report
• Conversion report
• Agencies login/admin
• Campaigns management
• Agent event report
• Event detailed report
• Conversion report
Ads Management System for Super App Users
I implemented an ad management system for Ayoba users, which has the following functionalities:
• Allows different ad providers like AdMob and Mobucks.
• Provides CRUD functionalities to allow consumption of these banner ads.
• Creates and schedules campaigns from start to finish.
• Creates static web URLs with content to serve as a landing page for agencies.
• Provides data pipelines to support any reporting requirements, such as requests, impressions, clicks, and conversions.
• Allows different ad providers like AdMob and Mobucks.
• Provides CRUD functionalities to allow consumption of these banner ads.
• Creates and schedules campaigns from start to finish.
• Creates static web URLs with content to serve as a landing page for agencies.
• Provides data pipelines to support any reporting requirements, such as requests, impressions, clicks, and conversions.
Hvac System & APIs Integeration
https://www.carrier.com/residential/en/us/access-your-thermostat/smarthome-app/Carrier is a global leader in intelligent climate and energy solutions, delivering advanced HVAC technologies worldwide.
• Led the current development team to enhance the product and augment its capabilities.
• Design and execute comprehensive load and performance test suites using Grafana K6.
• Deploy, scale, and troubleshoot services within Kubernetes environments.
• Build and maintain Kafka-based event-driven pipelines.
• Contribute to back-end development using Python and/or NestJS.
• Analyze system metrics and logs to proactively identify and resolve performance issues.
• Experience analyzing system performance, identifying bottlenecks, and resolving infrastructure/application issues.
• Led the current development team to enhance the product and augment its capabilities.
• Design and execute comprehensive load and performance test suites using Grafana K6.
• Deploy, scale, and troubleshoot services within Kubernetes environments.
• Build and maintain Kafka-based event-driven pipelines.
• Contribute to back-end development using Python and/or NestJS.
• Analyze system metrics and logs to proactively identify and resolve performance issues.
• Experience analyzing system performance, identifying bottlenecks, and resolving infrastructure/application issues.
API Security Platform
• AI-driven Attack Simulations: Automatically maps every API endpoint and runs thousands of simulated attacks to find logic flaws, data exposures, and OWASP Top 10 issues.
• Continuous and Integrated Testing: Embeds into the SDLC and CI/CD pipelines, testing every release in pre-production. It integrates with tools like Kong, Apigee, AWS, Jira, ServiceNow, and GitHub.
• Real Exploits, No False Positives: Delivers verifiable, actionable findings instead of theoretical vulnerabilities.
• Comprehensive Coverage: Detects complex issues like BOLA (Broken Object Level Authorization) and multi-step attack chains across all endpoints.
• Audit and Compliance Ready: Produces pentest-style reports mapped to standards (SOC 2, PCI, HIPAA, GDPR, ISO 27001).
• Deployment Flexibility: Available as cloud-native, on-prem, or hybrid with hosted agents for internal/private APIs
• Continuous and Integrated Testing: Embeds into the SDLC and CI/CD pipelines, testing every release in pre-production. It integrates with tools like Kong, Apigee, AWS, Jira, ServiceNow, and GitHub.
• Real Exploits, No False Positives: Delivers verifiable, actionable findings instead of theoretical vulnerabilities.
• Comprehensive Coverage: Detects complex issues like BOLA (Broken Object Level Authorization) and multi-step attack chains across all endpoints.
• Audit and Compliance Ready: Produces pentest-style reports mapped to standards (SOC 2, PCI, HIPAA, GDPR, ISO 27001).
• Deployment Flexibility: Available as cloud-native, on-prem, or hybrid with hosted agents for internal/private APIs
Education
2006 - 2008
Master's Degree in Computer Engineering
Marmara University - Istanbul, Turkey
2001 - 2006
Bachelor's Degree in Computer Engineering
Karadeniz Technical University - Trabzon, Turkey
Certifications
OCTOBER 2026 - PRESENT
AI System Design For Engineers and Interviews
Udemy
MAY 2025 - PRESENT
How To Become A Shopify Expert (From Zero To Hero!)
Udemy
MAY 2025 - PRESENT
Modern React with Redux
Udemy
APRIL 2025 - PRESENT
NestJS: The Complete Developer's Guide
Udemy
MARCH 2025 - PRESENT
Understanding TypeScript
Udemy
DECEMBER 2024 - PRESENT
AI For Developers With GitHub Copilot, Cursor AI & ChatGPT
Udemy
AUGUST 2024 - PRESENT
Generative AI for NodeJs: OpenAI, LangChain - TypeScript
Udemy
MAY 2024 - PRESENT
Artificial Intelligence A-Z 2024: Build 7 AI + LLM & ChatGPT
Udemy
JANUARY 2024 - PRESENT
Executive Briefing: Artificial Intelligence (AI) + ChatGPT
Udemy
NOVEMBER 2023 - PRESENT
To-Do App with Jetpack Compose MVVM - Android Development
Udemy
JULY 2023 - PRESENT
ChatGPT Complete Guide: Learn Midjourney, ChatGPT4 & More
Udemy
AUGUST 2021 - PRESENT
AWS Essentials
Udemy
AUGUST 2021 - PRESENT
Kotlin for Java Developers
Udemy
JUNE 2021 - PRESENT
Mockito Next Level Java Unit Testing
Udemy
JUNE 2020 - PRESENT
Junit 5
Udemy
MARCH 2019 - PRESENT
Agile Software Development
Scrum.org
FEBRUARY 2019 - PRESENT
Professional Agile Leadership I
Koc University
AUGUST 2018 - PRESENT
Data Analyst Nanodegree
Udacity
MARCH 2013 - PRESENT
Java Performance Tuning and Optimization
Oracle
Skills
Libraries/APIs
REST APIs, API Development, JDBC, JAX-WS, Node.js, Lombok, Java Servlets, OpenAPI, WebRTC, Twilio API, Java Message Service (JMS), GCM, WhatsApp API, OpenAI API, ZeroMQ, Asyncio, Python API, React, Protobuf
Tools
IntelliJ IDEA, Git, Grafana, Kafka Streams, Jira, Bitbucket, Kong, Apache Tomcat, Postman, Apache Maven, GitLab CI/CD, GitLab, Gradle, Cucumber, GitHub, MQTT, Amazon CloudWatch, Amazon ElastiCache, Google Analytics, BigQuery, Claude Code, Slack, Apache JMeter, Flink, NGINX, Jenkins, Firebase Cloud Messaging (FCM), Apache Avro, ChatGPT, Keycloak, ActiveMQ, Google Kubernetes Engine (GKE), Android Jetpack, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), AWS IAM, Crashlytics, Figma, Amazon Cognito, Grafana k6, Claude, CircleCI, Zoom, AWS Step Functions, AWS Cloud Development Kit (CDK)
Languages
Java, SQL, C, Python, Kotlin, JavaScript, TypeScript, HTML, Python 3, Java 7, PHP, Gherkin, Scala, CSS, Lua, C++
Frameworks
Spring Boot, Spring 4, Spring, Spring MVC, JSON Web Tokens (JWT), Angular, Swagger, JNI, Hibernate, JPA, OAuth 2, Spring Microservice, JavaScript MVC, Spring Security, Ionic, Bootstrap, JUnit, Mockito, Akka, Spring 5, NestJS, Django, Next.js, Redux, Selenium, Apache Struts, Micronaut, gRPC
Paradigms
Agile Software Development, REST, Load Testing, Microservices, Agile, Object-oriented Programming (OOP), Serverless Architecture, Event-driven Architecture, Event-driven Programming, Back-end Architecture, Agile Project Management, Scrum, Event-driven Design (EDD), Scalable Application, API Architecture, Role-based Access Control (RBAC), Parallel Programming, Unit Testing, Microservices Architecture, Test-driven Development (TDD), Continuous Delivery (CD), Domain-driven Development, CQRS, Automated Testing, Continuous Integration (CI), ETL, HIPAA Compliance, Testing, Refactoring
Platforms
JVM, Apache Kafka, Java EE (Jakarta EE), Linux, Oracle, Docker, Amazon Web Services (AWS), Google Cloud Platform (GCP), AWS Lambda, Firebase, Google Ads, Red Hat Linux, Red Hat OpenShift, Apache Flink, OpenShift, Mobile, Twilio, Amazon EC2, Kubernetes, Android, Azure, iOS, Mixpanel, Shopify, Confluent
Storage
Redis, NoSQL, Relational Databases, Redis Cache, RDBMS, MySQL, Cassandra, PostgreSQL, Databases, Amazon DynamoDB, Amazon Aurora, On-premise, MongoDB, SQL Stored Procedures, Google Cloud, Amazon S3 (AWS S3), Datadog
Industry Expertise
Telecommunications, Project Management, Healthcare, High-frequency Trading (HFT), Trading Systems
Other
Software Development, Performance, Multithreading, VoIP, Leadership, APIs, Code Review, Message Queues, SOLID Principles, Back-end, Technical Leadership, Architecture, Communication, SOAP, Team Leadership, Source Code Review, Technical Hiring, Interviewing, Integration, API Integration, CRM APIs, XMPP, Software Design, Low Latency, Task Analysis, Software Architecture, WebLogic, CTO, Back-end Development, HTTP REST, Messaging, Live Chat, API Platforms, Advisory, Scalability, Process Development, Engineering, Large-scale Projects, Large-scale Distributed Systems, Concurrent Computing, Networking, Technical Architecture, Team Mentoring, Multiprocessing, Enterprise, RESTFul APIs, Engineering Management, System Integration, API Design, API Testing, SQL Server, System Architecture, Performance Improvement, Performance Optimization, Fractional CTO, Real-time Data, Java Native Interface (JNI), Distributed Systems, SIP, Coherence, SMS, Pull Requests, Scripting, Full-stack, Chatbots, Containerization, WebSockets, Data Processing, SSL, Amazon RDS, API Gateways, Multitenancy, Containers, Session Initiation Protocol (SIP), Full-stack Development, Cryptography, Scrum Master, Video Calling, Stream Processing, Cloud Architecture, Apache Cassandra, Integration Testing, UDP, Big Data, Video Streaming, OAuth, Cloud, Payment Gateways, Technical Project Management, Financial Systems, Jitsi, Jitsi Videobridge, Memory Leaks, Network Protocols, Telemetry, OpenStack Swift, Payment APIs, IPsec, IDS/IPS, High-load, CI/CD Pipelines, Predictive Modeling, Data Wrangling, Probability Theory, Open Source, Statistics, Web Scraping, HTTP, APNs, Prometheus, Single Sign-on (SSO), Finance, OpenAI, Data Science, Artificial Intelligence (AI), Lambda Functions, Serverless, Data Engineering, Peer-to-peer Networking, VoIP Administration, WhatsApp Business, WhatsApp, Data Migration, Aeron, FIX Protocol, Amazon Kinesis, Security Groups, GitHub Copilot Chat, Trading, OWASP Top 10, OWASP, TypeORM, Google AdMob, Google BigQuery, ChatGPT API, Over-the-top Content (OTT), Startups, ElastiCache, Security, AdMob, Retrieval-augmented Generation (RAG), Vector Databases, Fintech, Prompt Engineering, Data Analytics, TimescaleDB, Argo CD, BullMQ, Cursor AI, Open Automated Demand Response (OpenADR), PCI DSS, FedRAMP, HIPAA, ISO 27001, Agentic Coding, System Design
Collaboration That Works
How to Work with Toptal
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1
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2
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