SENIOR .NET DEVELOPER — INTEGRATIONS & APIs Nearshore?Remote | Contract, full-time (40 hrs/week) | Colombia

Own the places where money actually moves

We're looking for a Senior .NET Developer to own the boundary between our platform and everyone else's. Our system talks to a card processor, an ACH gateway, QuickBooks, Twilio, Mailchimp, and Slack — mostly over REST — and those integrations are getting rebuilt as part of a larger modernization. This is where money leaves and arrives, so precision here isn't optional, it's the job.

If you like the kind of problem where "it worked" isn't good enough until you've also proven it can't double-charge anyone — this seat is for you.

What you'll be doing

- Reimplementing existing third-party integrations against modern clients — the card processor, ACH gateway, QuickBooks, Twilio, Mailchimp, and Slack.
- Handling the unglamorous parts properly: retries, idempotency, timeouts, and partial failures, so a hiccup on someone else's end never turns into a mistake on ours.
- Reconciling what a vendor says happened against what we actually recorded — because those two stories don't always agree, and figuring out why is half the work.
- Building internal APIs for the modernized system.




- Carrying a share of legacy corrective maintenance on the existing integrations.

What you'll need

- Strong C# and ASP.NET 4.7, plus .NET 8 and .NET 10
- Real, hands-on REST integration experience against third-party services you don't control
- A genuine understanding of idempotency and retry semantics — double-charging someone is the failure we're designing against
- Comfort reading vendor documentation that is, itself, sometimes wrong
- Professional English, spoken and written
- Minimum 4 hours of overlap with US Central time
- Availability for full-time work, 40 hours/week

Nice to have

- Experience integrating payment gateways or accounting systems specifically
- Web hook handling experience
- Experience reconciling financial records across systems

One more thing we look for in every seat Comfort working with AI-assisted development tools — not just using them, but directing an agent well on real work and reviewing what it hands back before it ships. If you already think this way, you'll feel at home here.

Good to know

This seat works in non-production environments only, with synthetic or sanitized data. You'll write the fixes for legacy issues, but deployment and production data access sit outside this role.

📌 SENIOR .NET DEVELOPER — INTEGRATIONS & APIs (Colombia)
🏢 Modern Intelligent Systems
📍 Colombia