Senior Software Engineer, Developer Platform

Senior Software Engineer, Developer Platform

MoonPay is a regulated financial infrastructure company operating across multiple jurisdictions including the United States, United Kingdom, European Union, Canada and Australia. The company powers value movement through crypto, stablecoins and tokenized assets for 30 million customers and over 500 ecosystem partners. Recently recognized as one of Forbes' America's Best Startup Employers 2026 and ranked second in Crypto Services on Fortune's inaugural Crypto 100 list, MoonPay operates as a high-standards, high-velocity organization where AI is embedded as a default operating mode and outcomes drive decision-making over process.

This role leads the developer platform team, sitting between MoonPay's core payments infrastructure and the products that partners build. You will design and implement the complete set of developer-facing tools, APIs, SDKs and embedded components that allow external developers to create native payment experiences inside their own applications without requiring ongoing implementation support from MoonPay's team.

What you'll do

• Design and build production APIs, SDKs and embedded components that external developers integrate into their products across browsers, mobile applications and backend systems.

• Transform MoonPay's existing authentication, identity, KYC, quotes, payment methods and purchasing capabilities into reusable, stable platform modules with clear abstractions.

• Develop secure integration patterns across iframes, web views and native applications, ensuring consistent behavior and security when operating inside products MoonPay does not control.

• Own the complete developer journey from credential management through live transaction completion, including sessions, authentication, error handling and transaction state management.

• Build APIs and SDKs that are difficult to misuse with straightforward debugging, plus reference applications and sandboxes that help developers move quickly from exploration to production.

• Design for reliability in payment-critical systems by implementing idempotency, state recovery and graceful degradation to handle retries, duplicate events, delayed responses and failing dependencies.

• Establish versioning, compatibility and migration strategies while creating documentation that reflects how developers actually use the platform.

What you'll bring

• Proven experience building external developer products including APIs, SDKs, embedded components or integration tooling used by third-party developers at scale.

• Deep understanding of how browsers and mobile applications behave at the framework level, including sessions, storage, cross-origin communication and embedded experiences.

• Strong production experience with JavaScript and TypeScript, particularly building client-side or SDK infrastructure.

• Solid grasp of distributed systems principles including handling events that arrive twice, late or out of order and dependencies failing unexpectedly.

• Demonstrated product judgment that translates complex platform capabilities into interfaces developers can easily understand and adopt.

• Track record of taking developer-facing software from design through launch, adoption and ongoing production support with full ownership.

Nice to have

• Direct experience building payment APIs, checkout SDKs, embedded financial products or payment-method integrations.