Golang Engineer with Trading Experience [part-time]

On behalf of our client from Estonia, Mobilunity is looking for a Golang Engineer with Trading Experience [part-time]. 

Our client is a technology-driven organization specializing in applying advanced data science and predictive analytics to market forecasting. The team designs, develops, and deploys statistical and machine learning models to support real-time decision-making in complex and dynamic environments. Their internal research unit is dedicated to continuously advancing methodologies and exploring innovative approaches that extend beyond the current industry standards.

We are looking for an experienced Golang Engineer to test, debug, and finalize the API integration of the OKX exchange into our real-time trading engine. The integration code is partially AI-generated, has undergone a superficial review, and requires thorough validation and targeted testing. The trading engine already supports integrations with three other exchanges, built by hand to a defined interface and implementation pattern. You will work directly with our team, testing the OKX integration in a live environment, fixing issues as needed, and adding targeted automated tests for critical execution paths.

Key Responsibilities:

• Test the existing OKX integration code in a live environment using small transaction amounts (~$10).
• Verify WebSocket reconnection scenarios.
• Investigate and address order lifecycle race conditions:
• Place order → immediate cancel
• Partial fill → cancel remaining
• Network disconnect during order placement
• Orders improperly marked as cancelled
• Orders remaining in cache but actually cancelled
• Write unit tests for key functions.
• Implement small integration test scenarios with mocked APIs for critical paths.
• Document unexpected behavior and create non-regression tests for OKX-specific quirks.
• Ensure all implemented tests are relevant and effective — no redundant or low-value tests.

Expectations:

• Plan and execute the work efficiently; estimated duration is 5–6 working days for an experienced engineer, assuming no major implementation issues.
• Focus on quality over quantity for tests — priority on critical execution paths and reproducible real-world scenarios.
• Collaborate closely with our internal team and follow the existing integration guide and reference implementations.
• Deliver clear documentation for any issues found and solutions applied.

Required Skills & Experience:

• 3+ years of professional experience in Golang development.
• Proven experience with API integrations in trading or similar real-time systems.
• Strong understanding of WebSocket connections and reconnection handling.
• Experience writing unit and integration tests (preferably in Go).
• Knowledge of order lifecycle management in trading environments.
• Ability to debug, optimize, and adapt partially implemented code.
• Solid written and verbal English skills.

Nice to Have:

• Familiarity with cryptocurrency exchange APIs (OKX, Binance, FTX, etc.).
• Experience working with AI-generated code and refactoring it for production readiness.
• Understanding of non-regression testing principles.

Joining the team you will get:

• The friendliest community of like-minded IT-people
• Open knowledge-sharing environment – exclusive access to a rich pool of colleagues willing to share their endless insights into the broadest variety of modern technologies
• Perfect office location in the city-center (900m from Lukyanivska metro station with a green and spacious neighborhood) or remote mode engagement: you can choose a convenient one for you, with a possibility to fit together both
• No open-spaces setup – separate rooms for every team’s comfort and multiple lounge and gaming zones
• Neverending fun: sports events, tournaments, music band, multiple affinity groups

Come on board, and let’s grow together!