Abdulhalim Kara
Verified Expert in Engineering
Full-stack Developer
London, United Kingdom
Toptal member since August 18, 2023
Halim is a senior software engineer with 17 years of experience developing scalable and performant microservices and web and mobile applications. Passionate about using the latest technologies, he is proficient in JavaScript, Node.js, React, React Native, MySQL, Python, and AWS. Halim is also experienced in AI and excels in designing and implementing robust solutions and building cutting-edge applications from end to end.
Portfolio
Experience
- JavaScript - 17 years
- Node.js - 8 years
- React - 6 years
- Serverless - 6 years
- React Native - 3 years
- Artificial Intelligence (AI) - 2 years
- Python - 2 years
- Elasticsearch - 1 year
Availability
Preferred Environment
MacOS, IntelliJ IDEA, Slack, iTerm2
The most amazing...
...thing I achieved was improve the OpenSearch performance by 4x while reducing the cost by 60% in two months. I had zero OS experience when I joined the project.
Work Experience
Senior Software Engineer
Asset Panda LLC - Main
- Managed cross-functional integrations by architecting and designing distributed, scalable systems to ensure optimized performance and cost efficiency.
- Mentored teams in TypeScript, testing, and code quality standards, contributing to company-wide best practices.
- Innovated cloud architecture strategies, focusing on serverless and microservices-based solutions, achieving a 4x increase in Lambda cold-start performance.
- Led the design and implementation of resilient distributed systems, reducing costs by 60% and enhancing OpenSearch performance by 4x.
- Implemented serverless solutions to streamline development and operational processes, reducing Lambda cold-start time to 500ms.
- Orchestrated data migrations for DynamoDB, ensuring zero downtime during transformations of 50+ million records.
Senior Full-stack Engineer
QMetric Group
- Re-engineered the company website with a microservices architecture, resulting in a 10% sales increase and 20% user growth.
- Designed payment UIs that are compliant with accessibility standards using React and TypeScript, improving user experience.
- Utilized AWS Lambda and DynamoDB for high-availability payment processing across multi-AZ deployments.
Senior Full-stack Engineer
Eurostar
- Developed scalable Node.js booking applications for high-traffic use, supporting internal teams across call centers and stations.
- Enhanced client-server interactions with Apollo for efficient data management across the front and back ends.
- Used Apollo Client with React on the front end and Apollo Server with Koa and Express.js frameworks on the back end.
Senior Full-stack Engineer
Dosh
- Built microservices for onboarding 4+ million Venmo users, handling rapid scaling and data processing with AWS Lambda and GraphQL.
- Implemented GraphQL communication with Apollo, optimizing client and back-end interactions for faster and more efficient data processing.
- Developed key services like MatchingEngine, Wallet, and OfferService, ensuring robust performance for payment processing and user transactions.
- Used MySQL and PostgreSQL for relational databases and DynamoDB for NoSQL.
Senior Full-stack Engineer
Crossover
- Rebuilt the user interface of legacy products to a standard tech stack, building and reviewing new screens with modern UI and enhanced usability.
- Reviewed the code quality of UI and REST API unit tests and functional browser compatibility testing.
- Enforced code quality standards through code reviews, automated testing, and continuous integration, resulting in stable and reliable software solutions.
Senior Full-stack Engineer
Parse
- Architected and developed eCommerce and mobile applications using React Native.
- Engaged in direct client interactions, ensuring seamless communication and understanding of project requirements.
- Worked with a diverse technology stack, including AWS Services, Node.js, React, React Native, Vue, GraphQL, Docker, Kubernetes, JavaScript, GitLab CI/CD, PHP, MySQL, and Redis.
Lead Software Engineer
INT Group
- Provided guidance and mentorship to a team of developers, fostering skill development and promoting a collaborative and innovative work environment.
- Developed and executed technical strategies aligned with business goals, leading the team to achieve product milestones and optimize performance.
- Participated in the recruitment process by interviewing candidates and playing a key role in onboarding new team members.
- Designed scalable and robust software architectures, ensuring long-term maintainability, flexibility, and adherence to industry best practices.
- Managed project timelines, resources, and deliverables, coordinating cross-functional teams to ensure timely project completion.
- Worked on web and iPad applications for international medical clients such as Bayer, Novo Nordisk, and Takeda.
Senior Full-stack Engineer
INT Group
- Joined the company as a full-time developer about one year after working with them as a freelance.
- Designed and developed medical iPad applications for INT Group clients.
- Used PhoneGap, JavaScript, jQuery, and Bootstrap to develop iPad applications and Node.js, PHP, and MySQL for developing back-end applications.
Senior Software Engineer
Advancity
- Worked on a startup project for an American company partnering with Advancity.
- Developed the company's official mobile application, a remote education app, with Adobe Flex.
- Architected and developed back-end systems with PHP, MySQL, and Apache Solr. Used AngularJS and Bootstrap for the front end.
Senior Full-stack Engineer
Freelance Clients
- Developed and designed eCommerce and micro websites and Flash applications for different clients.
- Designed and developed my 1st startup project, dukon.co, and sold it out to an Australia-based company, DreamPushers, in 2012. We set up a company in Delaware, USA, and then I sold out all my shares.
- Used a diverse technology stack including Node.js, Socket.io, PhoneGap, AngularJS, Bootstrap, JavaScript, HTML, CSS, PHP, MySQL, WordPress, and Magento.
Lead Software Engineer
Voden
- Provided guidance and mentorship to a team of engineers, fostering skill development and promoting a collaborative and innovative work environment.
- Participated in the recruitment process by interviewing candidates and contributing to the onboarding of new team members.
- Managed project timelines, resources, and deliverables, coordinating cross-functional teams to ensure timely project completion.
- Developed and executed technical strategies aligned with business goals, leading the team to achieve product milestones and optimize performance.
- Designed scalable and robust software architectures, ensuring long-term maintainability, flexibility, and adherence to industry best practices.
- Worked directly with clients such as ING Bank, Garanti Bank, and BKM.
Software Engineer
Intro Production
- Developed iPad and iPhone applications for companies in the medical industry, including Novo Nordisk, Bayer, Takeda, and Boehringer.
- Used PhoneGap and Objective-C for developing iPad applications.
- Worked with PHP, MySQL, JavaScript, and ActionScript.
Experience
OpenFaceID | Identity Verification with Facial Recognition
https://github.com/ahalimkara/openfaceidThis project aims to deliver a seamless and reliable user experience for identity verification in various applications.
An Edtech App for Students
https://nsinav.comnSınav is an edtech platform that benefits from comprehensive technologies. PHP, MySQL, and NGINX power its back-end operations, while front-end development relies on AngularJS, Bootstrap, HTML, and CSS. The platform also offers mobile accessibility through React Native, and its deployment is managed using Docker for scalability.
Education
Bachelor's Degree in Computer Science
Dokuz Eylul University - Izmir, Turkey
Certifications
AWS Certified Solutions Architect – Associate
Amazon Web Services
Skills
Libraries/APIs
Node.js, React, REST APIs, React Testing Library, Ramda, jQuery, X (formerly Twitter) API, Stripe, Stripe API, Twilio API, PayPal API, Vue, Stripe Connect, RxJS, Socket.IO, Amazon API, Plaid API, Venmo API, WordPress API, API Development, Singularity.js, Shopify API
Tools
Amazon CloudWatch, Mocha, Babel, Webpack, React Apollo, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), AWS Step Functions, Jira, NGINX, GitLab, Sentry, Amazon OpenSearch, AWS CloudFormation, Traefik, Terraform, Figma, Google Analytics, IntelliJ IDEA, Slack, AWS SDK, AWS Fargate, TeamCity, Kibana, GitHub, CircleCI, AWS IAM, GitLab CI/CD, Amazon Elastic Container Service (ECS), Karma, Apache Solr, Bitbucket, InVision, Plaid, Expo, Microsoft Excel, Autodesk 3ds Max, 3ds Max, wkhtmltopdf, Cron, Nx, AWS AppSync, AWS Cloud Development Kit (CDK)
Languages
TypeScript, GraphQL, JavaScript, PHP, HTML, CSS, SQL, HTML5, Python, Less, Sass, ActionScript 3, Active Server Pages (ASP), Objective-C, Java
Frameworks
Express.js, Jest, Cypress, Koa, React Native, Vanilla JS, Next.js, Redux, Laravel, Nuxt.js, Angular 2, Bootstrap, PhoneGap, .NET, Angular, Jasmine, AngularJS, Adobe Flex, CodeIgniter, Hapi.js, PHP MVC, Yii, NestJS
Paradigms
Agile Software Development, Object-oriented Programming (OOP), Responsive, Microservices, Microfrontends, Microservices Architecture, Responsive Web Design (RWD), REST, Mobile Development, Serverless Architecture, Lambda Architecture, Hosting
Platforms
AWS Lambda, Docker, Amazon EC2, WordPress, Magento, Amazon Web Services (AWS), OpenCart, Twilio, Mandrill, Mobile, Linux, Vercel, MacOS, Kubernetes, Android, iOS, Shopify
Storage
MySQL, PostgreSQL, Amazon S3 (AWS S3), Amazon DynamoDB, Redis, NoSQL, RDBMS, Amazon Aurora, Elasticsearch, MongoDB, Datadog, Amazon Simple Workflow Service (SWF), MSSQLCE, SQLite, OVH, JSON, Cloud Deployment
Industry Expertise
Web Design
Other
Computer Science, Styled-components, Enzyme, GitHub Actions, Apollo Server, Storybook, Nock, Serverless, WebSockets, AWS WAF, Amazon API Gateway, Web Scraping, User Interface (UI), User Experience (UX), Accessibility, Agile Sprints, Architecture, SaaS, MVP Design, VPS/VDS, SMS, Stripe Payments, PayPal, Mobile UI, Mobile UX, Mobile Apps, Mobile App Development, Booking Apps, Booking, Booking Systems, CI/CD Pipelines, Front-end, Back-end, APIs, API Gateways, Mobile First, 3D, Marketplaces, Data Scraping, Web Development, API Integration, Asynchronous I/O, Responsive Web Apps, Early-stage Startups, Startups, Lambda Functions, Infrastructure as Code (IaC), Artificial Intelligence (AI), Machine Learning, Vector Databases, eCommerce, Design, Google Tag Manager, iTerm2, Mastercard, Online Payments, Payment Gateways, Payment APIs, Digital Payments, Cash Flow, Card Payments, Worldpay, Memory Leaks, Memory Management, Full-stack, Business Services, Axios, Server-side PDF Generation, PDF, Papervision3D, Cloud Architecture, Cloud Services, Cloud Infrastructure, Cloud, Cloud Migration, Cordova, Buffer Management, Solution Architecture
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