Software Engineer

CONSTANT Digital is a small founding team building a B2B cross-border payments platform for importers and exporters. You will own the codebase with us: extend it, integrate outside services, and keep it dependable once it is live. The work touches real payment flows. Careful engineering and good judgment matter more than speed.
We use AI coding tools and want someone who uses them well. We also want someone who can do this job without them (hence not just a vibecoder you need to understand how to code and read code).
What you’ll do
Build and ship features across the backend and the web application.
Build and maintain integrations with payments and compliance APIs: authentication, webhooks, idempotency, retries and failure handling.
Review, test and take responsibility for every change that lands, whether you or a tool wrote it.
Debug production issues, find the root cause, and stop them recurring.
Own deployments, monitoring and logging.
Keep short technical notes so the founders always know the state of the system.
What we’re looking for
Strong fundamentals in a modern backend (Node/TypeScript or Python), SQL, and a web frontend. You can read unfamiliar code, trace a bug by hand and explain what a piece of code does and why.
Experience integrating third-party APIs and handling partial failure, duplicates and retries.
Experience shipping and running production software: monitoring, logs and live debugging.
A security-first approach to financial data: access control, secrets and audit trails.
The judgment to catch bad AI output: security holes, hidden bugs, invented APIs, and code that looks right but fails on real data.
Fluent, controlled use of AI tools: you know when to use them, how to prompt them and when to stop trusting them.
Fintech, payments or banking integration experience is a strong plus.
Independent, reliable, and clear in writing.
How we hire: we will ask you to read existing code and walk through a real integration or production-debug problem. We are hiring for that, not for a polished application.
The arrangement Part-time contract to start, with a path to full-time if it is a fit. Remote, with agreed hours and response times. Rate based on experience and hours.
(Optional) Send a link to code you wrote (repo, PR or gist) and a short note covering: a payments or API integration you built and how you handled idempotency or failure; a production issue you debugged from code or logs; a time an AI tool gave you something wrong and how you caught it.

Work arrangement
Yes