Product-Minded JavaScript Developer (Mid-Level)

Product-Minded JavaScript Developer (Mid-Level)

The role

Fena is looking for a mid-level JavaScript developer who thinks like a product person. You will design, wire and ship API-driven payment and commerce features, and you will own whether they actually work for the merchant on the other end.

Fena Labs is a UK-regulated payment institution (FCA FRN 934835). We run two products: an Open Banking payments suite (Pay by Bank, Pay by Link, Bulk Payments, Variable Recurring Payments, QR codes) and a B2B commerce toolkit for wholesalers (Shopify Wholesale App, invoicing, inventory, order management). Our corridors cover the UK and all 27 EU countries, and our team is distributed across the UK, Moldova, Pakistan and the Philippines.

We are a small 40-people strong team. Nobody here writes every line by hand any more; AI tools do a lot of the typing. What we need is someone who knows what to build, can read an API spec and see the product in it, and can tell when generated code is wrong.

What you'll actually do

• Turn a merchant problem into a shippable feature: scope it, sketch the API and data flow, build it, release it, watch how it's used.
• Integrate third-party APIs (banking providers, Shopify, payment partners, KYC/AML tools) and make them feel like one product.
• Design and maintain our own APIs and webhooks so partners and merchants can build on Fena.
• Work with AI coding tools daily, and review what they produce as carefully as you would a junior colleague's pull request.
• Debug production issues end to end: a failed payment might be our code, a bank's API, a webhook retry or a merchant's config, and you'll work out which.
• Write short, clear specs and docs: for the team, for partners, for the merchant-facing help centre.
• Talk to merchants and partners when needed. You'll hear the problem first-hand rather than through three layers of ticket.
• Keep regulatory constraints in mind (we are FCA-regulated), and know when to ask before you ship.

Who we're looking for

Must-haves

• 3 to 5 years building and shipping JavaScript/TypeScript products (Node.js on the back end; React or similar on the front end).
• Strong with REST APIs, webhooks, auth flows (OAuth2, API keys, signed requests) and the usual failure modes: retries, idempotency, timeouts, partial failures.
• Comfortable reading someone else's API docs and spotting what's missing or ambiguous before you build against it.
• Fluent with AI coding assistants, and honest about their limits. You can explain every line that goes into production.
• Product judgement: you ask "what is the merchant trying to do?" before "how do I implement this?", and you can push back on a feature that won't earn its keep.
• Clear written English. Most of our communication is async and in writing.
• Self-directed. You can take a loosely defined problem and come back with a plan, not a list of questions.

Nice-to-haves

• Experience in payments, fintech, Open Banking or another regulated space.
• Shopify app development, or other e-commerce platform integrations.
• Familiarity with PostgreSQL, cloud deployment (AWS, GCP or similar) and CI/CD.
• Experience with low-code or AI app-building platforms (we use Base44, Lovable and Replit for internal tools).
• You've worked in a small or early-stage company and know what it's like when there's no one else to hand it to.

Who this isn't for

• You want tickets handed to you fully specified. Here you'll often write the spec.
• You only want to code. You'll spend real time on scoping, docs and API design
• You need a large team around you. We're small and you'll own things end to end.
• You see AI tooling as a threat rather than a lever.

What we offer

• Fully remote, async-first. Work from where you are; overlap a few hours with UK time.
• Real ownership. Your features go to live merchants moving real money within weeks, not quarters.
• A seat close to the founder. You'll see how a regulated fintech is actually run, from product to compliance.
• Modern tooling and the freedom to use AI assistants the way you think works best.