Senior Software Engineer, Partner API (.NET)

Swyfft

1d • Remote

About The Position

Swyfft is hiring a senior engineer to own its Partner API full time and improve its developer experience so it is intuitive, consistent, well documented, and dependable as it evolves. The API enables partners to create and manage Swyfft insurance quotes from their own software. The engineer will design stable public resources over a rich insurance domain, work closely with partner engineering teams, and learn the existing codebase while bringing API expertise.

Swyfft’s production platform supports the insurance policy lifecycle, including rating, underwriting rules, policy issuance, endorsements, renewals, and claims. Its technology stack includes C#/.NET, TypeScript, SQL Server, and Azure. The technology team has about 30 people across development, support, IT, and QA. This is a 100% U.S.-based remote opportunity, available to candidates in the listed states. Some travel for team meetings and training may be required. Sponsorship is not available.

Requirements

• At least 7 years of experience as a backend developer, including at least 3 years building or maintaining a partner-facing or public API.
• Experience designing, shipping, and operating a REST API used by external developers in production, including maintaining backward compatibility through versions.
• Fluency in C#, ASP.NET Core, and SQL Server (MSSQL); experience with Azure.
• Knowledge of contract-first API development, including OpenAPI, schema evolution, deprecation policies, and changelogs.
• Knowledge of API security and multi-tenancy, including API keys or OAuth 2.0 client credentials, scopes, tenant isolation, and quotas.
• Ability to create a clean public API contract over a complex internal domain and explain the tradeoffs.
• Ability to work with developers at other companies and communicate clearly in documentation and email.
• Experience using AI coding agents effectively.
• A bachelor’s degree in Computer Science, Computer Engineering, or equivalent work experience.
• Reliable high-speed internet connectivity and a designated quiet work-from-home space.
• Experience with Microsoft Office and video and chat tools such as MS Teams and Slack.

Nice To Haves

• Insurance or fintech industry experience, including ACORD standards.
• API gateway experience, such as Azure API Management or similar.
• SDK generation and webhooks experience.

Responsibilities

• Own the Partner API contract end to end, including resource design, versioning, deprecation, and backward compatibility across releases.
• Design clear, consistent API resources and build a translation layer that keeps the public contract stable as internal systems evolve.
• Work directly with partner engineering teams to support integrations, including partner-specific development when needed.
• Design consistent error responses, idempotency, authentication, rate limiting, and usage metrics that show how partners use the API.
• Maintain accurate, current OpenAPI specifications and developer documentation, and create contract tests to catch breaking changes before partners do.
• Write and review production C# code, partner with QA and product, and ship through the release process.

Benefits

• Medical, dental, and vision coverage.
• Company-paid short- and long-term disability.
• Voluntary long-term disability.
• Company-paid employee life and AD&D insurance.
• Voluntary employee, spouse, and child life and AD&D insurance.
• Healthcare, dependent care, and transit flexible spending accounts, and a healthcare savings account.
• 401(k) with a generous matching contribution and no vesting schedule.
• 20 days of annual PTO, prorated based on hire date.
• Company-paid holidays and two “Choose Your Own Holidays.”

What This Job Offers

• Job Type: Full-time
• Career Level: Senior