Radoslav Peev Peev, Developer in Burgas, Bulgaria
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Radoslav Peev Peev

Verified Expert  in Engineering

Artificial Intelligence (AI) Developer

Burgas, Bulgaria
Toptal Member Since
September 3, 2017

Radoslav is a full-stack developer with a passion for electronics. Since 2009, he has worked remotely. Most recently, Radoslav has been working in a startup environment where deadlines are nearly every week, and choosing the correct technology is critical for the project.


Bank payment Startup
Node.js, Next.js, NestJS, React, React Native, PostgreSQL, Docker, ACH...
Prepay Nation LLC
Node.js, TypeScript, Amazon Web Services (AWS), Terraform, Docker...
Node.js, TypeScript, PostgreSQL, Amazon Web Services (AWS), Figma, Jira...




Preferred Environment

Git, Ubuntu

The most amazing...

...things I've developed in my last startup for Cardiology Telemedicine: analyze and transfer ECG PPG data from patients and display real time in medical centers.

Work Experience

Senior Full-stack Developer

2022 - 2024
Bank payment Startup
  • Created a fully-functional back end able to create transactions based upon the user or POS QR code present, card number with proprietary BIN number, or online transaction with user authentication and initiate ACH bank transaction through Plaid third-party service.
  • Built a web-based front end that can handle the user registration and authentication flow, review transactions, manage virtual cards, etc.
  • Developed a mobile application for Android and iOS with similar web functionality but can handle a more complicated registration flow, read driver license barcode details and verify the identity, compare with Plaid provided details, etc.
  • Created an admin panel for internal use and for merchants.
  • Made integrations with eCommerce web platforms with auth, capture, cancel, void, and refund functionalities.
Technologies: Node.js, Next.js, NestJS, React, React Native, PostgreSQL, Docker, ACH, Barcoding, QR Codes, Collaboration

Senior Lead Back-end Developer

2021 - 2022
Prepay Nation LLC
  • Implemented APIs and infrastructure from scratch. Set up AWS environments for development, staging, and production and a mono repo in GitHub for all the projects.
  • Set up a CI/CD automatic process based on GitHub actions for all the projects to AWS resources, network configuration, and security.
  • Onboarded and adopted several clients, providing mobile services to more than 200,000 customers.
  • Integrated payment methods with recurrent options, implementing proprietary payment services for third-party businesses to minimize payment fees.
  • Worked closely with designers and business logic creators to build clean and robust Figma charts for mobile applications.
  • Understood customer needs through customer service and made changes in the flows to satisfy the most common complaints.
  • Kept GitHub repositories and branches in a clean and tidy state, making it easy to keep track of everything while collaborating with other developers on a single mono repo.
  • Conducted GraphQL implementation for the client API and REST API for internal components like payments, fulfillment, etc.
Technologies: Node.js, TypeScript, Amazon Web Services (AWS), Terraform, Docker, Data Migration, Realtime, PostgreSQL 10, TypeORM, APIs, API Architecture, Software Architecture, Agile Software Development, REST APIs, WebSockets, React, Architecture, Mobile, Web Development, NestJS, GitHub, Amazon S3 (AWS S3), Amazon EKS, Cloud, Back-end, Amazon Simple Notification Service (Amazon SNS), Amazon Simple Queue Service (SQS), Amazon Cognito, Back-end Development, CI/CD Pipelines, Design Patterns, ESLint, PDF, Collaboration

Senior Back-end Developer

2020 - 2021
  • Developed the back end from scratch based on Node.js and TypeScript with self-creating swagger documentation. All project was deployed on AWS and custom policies were made. The repository was on Bitbucket and the CI/CD was done to the AWS service.
  • Tracked and fixed bugs with Jira as a reporting tool, helping our team keep in the same direction. I worked with five front-end developers and a QA.
  • Managed to work fast enough to support front-end developers and deploy the endpoints on time. We had Figma wireframes and UI designs, so all necessary information about the business logic is there.
  • Worked on dependency injection done with TypeDI, using TypeOrm for the database. Smart validation was done thanks to the class validator.
Technologies: Node.js, TypeScript, PostgreSQL, Amazon Web Services (AWS), Figma, Jira, Postman, Serverless, APIs, Microservices, API Architecture, Software Architecture, Agile Software Development, REST APIs, WebSockets, React, Architecture, Mobile, NestJS, GitHub, Amazon S3 (AWS S3), Real-time Systems, WebRTC, Cloud, Back-end, AWS Lambda, Jest, SST, Back-end Development, CI/CD Pipelines, Design Patterns, ESLint, Prisma, Collaboration

Security Improvements Developer

2020 - 2020
Advertise Purple
  • Implemented a more complex password policy, an SSH token renewal and rotation solution. Implemented an HMAC security authentication solution.
  • Configured and implemented AWS WAF protection and performed AWS code deployment by a centralized server solution with Bitbucket pipelines, a speed-up build time, and a deployment process. Implemented stream for all back-end logs to AWS CloudWatch.
  • Participated in the development process both on the back- and front-end. Wrote unit and E2E tests.
Technologies: Amazon Web Services (AWS), MySQL, Angular, Node.js, JavaScript, APIs, API Architecture, Software Architecture, REST APIs, WebSockets, Full-stack, Auth0, GraphQL, Web Development, GitHub, CircleCI, Cloud, Back-end, Graph Databases, Neo4j, Jest, Django, Back-end Development, CI/CD Pipelines, Design Patterns, Amazon DynamoDB, ESLint, PDF, Collaboration

Back-end Developer

2018 - 2020
  • Developed RESTful APIs from scratch for a mobile application for a client's app, a business app, and an administration panel.
  • Integrated payment methods including Stripe and Plaid.
  • Developed an administration panel based on React and participated in React Native apps for Android and iOS.
  • Optimized performance for intensive load with Redis cache.
  • Developed a chat server from scratch with a lot of features, as well as real-time updates in apps.
Technologies: React, Sockets, Redis, MongoDB, PostgreSQL, Node.js, Android, iOS, Linux, Ubuntu, APIs, Software Architecture, Agile Software Development, REST APIs, WebSockets, React Native, Architecture, NestJS, GitHub, Amazon S3 (AWS S3), Real-time Systems, Cloud, Back-end, AWS Lambda, Amazon Simple Notification Service (Amazon SNS), SST, Back-end Development, CI/CD Pipelines, PDF, Collaboration

Proof of Concept Developer

2018 - 2018
  • Deployed Python AI engine on premises. The main task was to add all new data to the training set.
  • Designed a Node.js-based back-end API to access the data from the AI engine.
  • Implemented an Apigee Edge API layer for security, load balancing and analytics, and response cache.
  • Utilized Kubernetes to configure and deploy Docker containers with Node.js on premises and use Apigee load balancer for scaling.
  • Added initial training data with Pandas and trained the regression AI with NumPy and scikit-learn.
Technologies: Swagger, Apigee, TypeScript, Docker, MariaDB, Node.js, Scikit-learn, Pandas, NumPy, Python, Software Architecture, Architecture, GitHub, Back-end, Back-end Development, Collaboration

Back-end Node.js Developer

2018 - 2018
Society Ltd. (via Toptal)
  • Developed the back-end logic for games, exchanging, depositing, and withdrawing steam-based items and skins.
  • Utilized RethinkDB as a general-purpose database, which gave some useful advantage of developing and scaling.
  • Ran each service of endpoints in a different docker container for low latency and high scalability by managing all with Rancher.
  • Developed a billing service where the payment was based on the G2A gateway.
  • Collaborated with the front-end developer and the team's lead back-end developer.
Technologies: Payment Processing, Rancher, Docker, Redis, RethinkDB, Async.js, Node.js, Kubernetes, APIs, Microservices, REST APIs, GitHub, Back-end, Back-end Development, Collaboration

Developer and Engineer

2017 - 2018
  • Implemented logic for take-off to locate the first electric pylon by entering GPS coordinates and tracking the next one using OpenCV and compass because of magnet induction on the cables.
  • Located the next pylon and took shots from above and side view, stored the geolocation point, and added details for the infrastructure point.
  • Exported GPS coordinates for flight roadmap, where the result was a professional video created from DJI software.
  • Used DJI SDK on Raspberry Pi with Pi camera mounted on a gimbal. Controlled the gimbal with the DJI API.
Technologies: Embedded C++, DJI SDK, Gimbal, Drones, Raspberry Pi, OpenCV, Navigation, Compass, Google Maps, Geolocation, Geolocation Detection, Full-stack, GitHub, Back-end, Back-end Development, Collaboration

Front-end and Back-end Developer

2017 - 2017
  • Added new features to the existing product. Made improvements in the front and back-end such as adding new objects and preparing thumbnails for the 3D object arranged in categories.
  • Created a marketplace and migrated from an existing CDN to a new one.
  • Dockerized the application and bundled scripts for the production stage.
  • Generated high and low-resolution mesh objects for front-end performance optimization.
Technologies: 3D, GridFS, Three.js, JavaScript, MongoDB, Node.js, REST APIs, WebSockets, Full-stack, Web Development, GitHub, Back-end Development, Collaboration

Full-stack Developer

2014 - 2017
CheckPoint R&D
  • Contributed to R&D of hardware of ECG medical device, and developed reliable Bluetooth Low Energy protocol for data stream using C++.
  • Developed Android application for communication with medical devices, Java-based QRS PPG detector, and vital data analysis.
  • Created scalable Node.js server with external C modules, for intensive stream loads with Socket.io solution, and live stream of real patients.
  • Designed and developed the company data architecture for transmitting, analysis, storage, and visualization.
  • Integrated MATLAB modules for research and training data for the future neural network (Python and C middleware components).
  • Deployed custom ERP and CMS systems in medical centers and hospitals using HTML5, SVG, D3.js visualization.
  • Developed web interfaces based on Angular framework for dynamic medical data CRUD and RESTful back-end API on Node.js, Expres; passport handle with authentication front-end requests and that can stay open for third-party medical ERP systems.
Technologies: Ubuntu, Git, MATLAB, Bluetooth LE, HTML5, D3.js, JavaScript, Java, MongoDB, MySQL, Angular, Socket.IO, Node.js, C++, Python, PHP, Embedded Software, Embedded Systems, Bluetooth, WiFi, Connectivity, Low-level Programming, Android, MySQL Server, Software Architecture, REST APIs, WebSockets, Full-stack, React, Architecture, Mobile, Web Development, GitHub, Parallel Programming, Real-time Systems, WebRTC, Back-end, Graph Databases, PDF, Collaboration, Internet of Things (IoT), IoT Protocols, MQTT

Co-founder and Consultant

2011 - 2013
R&D Partners
  • Created an R&D platform for tourism and travel management.
  • Maintained huge data storage of books and e-books with a two-way API service for book stores, including payment and discount solutions.
  • Developed iOS and Android mobile applications based on PhoneGap technology and custom native components.
  • Designed and developed eCommerce platforms for bookstores with responsive design and an AngularJS-based user interface for more flexibility.
  • Utilized Java and Objective-C modules for AMQP and API instant communication.
Technologies: Ubuntu, Bootstrap, AngularJS, jQuery, Objective-C, Java, SQLite, PhoneGap, AMQP, Sphinx Search Engine, MySQL, PHP, MySQL Server, Full-stack, GitHub, PDF, Collaboration

Senior Web Developer

2005 - 2011
  • Served as a team leader during the whole process of building custom cross-browser CMS and ERP development.
  • Developed payment and accounting solutions, business automation, e-business web portals, performance optimization, scalable architectures, and high-quality own megapixel IP and GPRS camera and video processing.
  • Created a real-estate framework for B2B and B2C web applications.
Technologies: FreeBSD, JavaScript, Sockets, Web Services, Git, PostgreSQL, MySQL, Python, C, PHP, MySQL Server, Full-stack, Web Development, GitHub, PDF, Collaboration

Charts PHP

This code is for creating graphs from vital parameters during a given period. The PHP script can be run only with the existing Microsoft SQL Server and the data inside it. Mainly, this script will create SVG charts with the D3.js module and tune up the style without using CSS because of the SVG support of the FPDF engine. The script is used to create a server-side DOM object with SVG tags that will be used for creating PDF protocol for the individual patient.
2002 - 2007

Bachelor of Science Degree in Electronics

Technical University - Sofia, Bulgaria

1994 - 2002

Diploma in Mathematics and Informatics

High School of Mathematics and Natural Sciences - Burgas​, Bugaria


Stripe API, Stripe Connect API, Twilio API, Node.js, Socket.IO, jQuery, React, API Development, REST APIs, WebRTC, D3.js, Google Maps, Google Maps API, Sockets, AMQP, Three.js, GridFS, NumPy, Pandas, Scikit-learn, Apigee, Vue, OpenCV, Slack API, Intercom API


Eclipse IDE, GitHub, Amazon Simple Notification Service (Amazon SNS), Amazon Simple Queue Service (SQS), Bitbucket, Auth0, Git, Notepad++, MATLAB, Terraform, GIS, Amazon EKS, CircleCI, Amazon Cognito, Prisma, MQTT, Mongoose, Figma, Jira, Postman, DJI SDK, Bluebeam


Koa, React Native, Express.js, NestJS, Jest, Next.js, Angular, Django, PhoneGap, AngularJS, Swagger, Bootstrap, Compass, Realtime


PHP, Python, HTML5, JavaScript, HTML, TypeScript, SQL, CSS, C, C++, Java, Solidity, GraphQL, Objective-C, Delphi, Embedded C++


DevOps, Object-oriented Programming (OOP), Agile Software Development, Unit Testing, E2E Testing, Microservices, API Architecture, Parallel Programming, Real-time Systems, Design Patterns, Mobile Development


Amazon Web Services (AWS), Docker, Amazon EC2, Ubuntu, Android, Apache2, Linux, Kubernetes, AWS Lambda, Visual Studio Code (VS Code), Mobile, FreeBSD, Bluetooth LE, Rancher, iOS, Raspberry Pi, Firebase


Redis, MongoDB, MySQL, Databases, MySQL Server, Amazon S3 (AWS S3), Graph Databases, Memcached, PostgreSQL, RethinkDB, Elasticsearch, Neo4j, Sphinx Search Engine, SQLite, MariaDB, PostgreSQL 10, NoSQL, Microsoft SQL Server, Amazon DynamoDB


Load Balancers, Web Security, Single-page Applications (SPA), Full-stack, SVG, APIs, Middleware, Third-party APIs, Software Integration, Software Implementation, TypeORM, Bluetooth, Low-level Programming, Connectivity, Embedded Software, Embedded Systems, Ubuntu Server, Serverless, Software Architecture, Back-end, WebSockets, Architecture, Web Development, Cloud, SST, PDF, Back-end Development, CI/CD Pipelines, ESLint, Barcoding, QR Codes, Collaboration, IoT Protocols, Push Notifications, AWS DevOps, Data Analysis, Digital Health, WiFi, Geolocation, ACH, Finance, Internet of Things (IoT), Web Services, 3D, Async.js, Payment Processing, Artificial Intelligence (AI), Machine Learning, Gimbal, Drones, Navigation, Data Migration, Geolocation Detection, DOM

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