Developer Experience Lead

Role overview

OpenFX has built a financial engine for institutional cross-border payments, but nobody yet owns how outside developers experience it. This role, reporting to the head of Product Growth, fixes that. You will be the first person in the Developer Experience function and will design the documentation ecosystem from scratch, set up the processes that stop it going stale as the platform changes, and work directly with the clients integrating against the APIs.

The job is judged on adoption rather than output. You will measure the path from key activation through first call, first transaction and wider endpoint use, then drive the work that moves those numbers. Alongside that you own the OpenAPI specification as a product contract, with spec linters blocking merges in CI and breaking changes routed through a defined deprecation process, and you join product and engineering design reviews in the role of first user, empowered to stop an API shipping if it cannot be explained clearly. Over time you will define what the DX discipline looks like at OpenFX, including an agent-experience roadmap covering CLI and MCP.

What you will do

• Own API adoption as a measured outcome: instrument the funnel from key activation to first call, first transaction and expanded endpoint usage, set baselines and targets, and lead the cross-functional work to improve them each quarter.
• Design and run docs-as-code documentation infrastructure that engineers can contribute to, judged by its effect on adoption rather than page count.
• Bring the OpenAPI spec into line with what runs in production, then enforce a contract-first governance model: linters as CI merge blockers, spec updates inside engineering's Definition of Done, automatic breaking-change detection and a formal deprecation path.
• Act as the first user in product and engineering reviews, with the authority to block APIs that are too hard to explain in writing.
• Produce technical content that earns developer trust, such as deep dives on idempotency under retries, sample apps showing real payment flows, and integration pattern guides aimed at PSPs, neo-banks and treasury teams.
• Represent OpenFX at developer events, conferences and partner enablement sessions as volume warrants, and turn integration friction into product changes through structured feedback loops.
• Serve as the first technical stop for clients' integration questions in US business hours, classifying each issue as a docs gap, an API design flaw or a bug, fixing docs directly and routing the rest to engineering with context.
• Build a repeatable onboarding playbook that replaces one-off Slack threads, partnering with GTM, who own the client relationship.
• Deliver a V1 public developer portal (references, guides, changelog, sample apps) with accurate request and response examples for every public endpoint.
• Write the DX roadmap covering SDK strategy, where the portal goes next, adoption analytics and the foundations of agent experience (CLI, MCP).

What the employer is looking for

• Five or more years running a developer-facing API platform or product in B2B or infrastructure, with a measurable adoption result you can point to, not just published pages.
• Hands-on client integration experience: you have joined integration calls with B2B or institutional customers, diagnosed problems live and fed them back into product changes.
• Firm opinions on API design, covering endpoint structure, parameter naming, authentication UX, error formats, idempotency keys and SDK ergonomics, plus a record of getting those changes shipped pre-release.
• Enough engineering fluency to read code independently, contribute usefully in code review and reason about latency, rate limiting, idempotency, eventual consistency and async patterns.
• Prior experience implementing or enforcing contract-first OpenAPI workflows where the spec is the product contract rather than a generated by-product.
• Fintech or financial services background on payments, trading or banking APIs; you know authorized from settled.
• An instinct for agent experience: you have built or at least trialled MCP servers, SDKs designed for agents, llms.txt files, LLM evaluation suites for API consumption or similar agent-readable patterns, and hold a view on what DX means once AI agents become primary consumers.

Good to have

• Experience with interactive documentation: code playgrounds, Try It Now features or in-browser sandboxes.
• Multimedia documentation skills, including video tutorials and sequence or architecture diagrams.
• Developer advocacy or DevRel background: external technical writing, shipped sample apps or presenting at developer events.

Benefits and compensation

• Competitive salary and benefits package.
• Equity in a fast-growing company.
• A chance to shape global financial infrastructure at an early-stage fintech.
• Collaborative culture with a focus on personal and professional growth.

About OpenFX

OpenFX is building the infrastructure behind institutional cross-border payments of the next generation, with the aim of letting money move as freely as data regardless of time zones, banking hours or legacy rails. Its early team includes alumni of Goldman Sachs, J.P. Morgan, PayPal, FalconX, Affirm, Kraken, Polygon and Nium, and investors include Lightspeed, Accel and NfX among others.