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# Software Developer, Partner API (.NET)

- **Company:** Swyfft Holdings, Llc
- **Location:** Ventura County, CA, United States (Remote available)
- **Experience:** Expert
- **Contract:** Permanent contract
- **Skills:** ASP.NET, Application Programming Interfaces (APIs), Microsoft Azure, C Sharp (Programming Language), Computer Engineering, Internetworking, Microsoft Office, Microsoft SQL Server, OAuth, Openapi, Software Security, AI Coding Agents, Backend, Information Technology, Api Gateway, Restful APIs, Webhooks, Api Management
- **Published:** October 20, 2026
- **Apply:** https://www.builtincolorado.com/auth/login?destination=/job/senior-software-engineer-partner-api-net/11753937

## About the Role

* 7+ years of experience as a backend developer, including 3+ years building or maintaining a partner-facing or public API.

Education:

 * A Bachelor's degree in Computer Science, Computer Engineering, or equivalent work experience is required.

Computer Skills:

 * Fluent in C#, ASP.NET Core, and SQL Server (MSSQL); experience with Azure.
 * We're a MS Office environment.
 * Experience using video and chat technology (MSTeams & Slack).

Nice to Have:

 * Insurance or fintech industry experience, including ACORD standards.
 * API gateway experience (Azure API Management or similar), SDK generation, and webhooks.

## Description

* Own the Partner API contract end to end: resource design, versioning, deprecation, and backward compatibility across releases.
 * Design clear, consistent API resources, and build the translation layer that keeps the public contract stable as our internal systems evolve.
 * Work directly with our partners' engineering teams to support their integrations, including partner-specific work on our side when an integration calls for it.
 * Design consistent error responses, idempotency, authentication, and rate limiting, along with the usage metrics that show how partners use the API.
 * Keep the OpenAPI spec and developer documentation accurate and current, with contract tests that catch breaking changes before partners do.
 * Write and review production C# code, partner with QA and product, and ship through our release process.

The Successful Candidate: (what we're looking for)

 * You've designed, shipped, and run a REST API used by external developers in production, and kept it backward compatible through versions. A few years on a well-known public API (payments, e-signature, communications) is exactly the kind of background we mean.
 * You think contract-first: OpenAPI, schema evolution, deprecation policies, and changelogs.
 * You know API security and multi-tenancy: API keys or OAuth 2.0 client credentials, scopes, tenant isolation, and quotas.
 * You've put a clean public contract in front of a complex internal domain and can explain the tradeoffs.
 * You like working with other companies' developers, and you write clearly for them in docs and email.
 * You know how to get the most out of AI coding agents; our team uses them every day.