Full-Stack Web Developer (TypeScript)
Summary
Feenko, a fast-growing personal-finance mobile app focused on the US market, is hiring a full-stack TypeScript developer to own its web funnel, admin panel, and support site. Day to day: ship A/B experiments, maintain Stripe/Solidgate payment integrations, and keep the revenue path stable using Astro/Next.js, Vercel, and PostgreSQL.
Feenko is a mobile product in the personal finance space that helps people track, understand, and control their spending and subscriptions.
We launched from scratch almost a year ago and already have 100,000+ users, positive unit economics, and rapid growth, with a primary focus on the US market. Backed by a recent partnership with Visa, we are unlocking new opportunities for scaling.
While mobile is the heart of our product, web is the heart of our growth: our web funnel is where users discover Feenko and become paying subscribers.
We are looking for a Full-Stack Web Developer (TypeScript) to take full ownership of Feenko's web direction. You will be the primary engineer behind our web funnel, admin panel, and support site — developing new features and A/B experiments according to designs and specs, integrating payment and third-party services, and keeping everything stable in production.
The funnel is revenue-critical and evolves fast: experiments ship weekly, and the quality bar is high — mistakes here directly affect the business. This role suits an engineer who values ownership, delivers quickly without sacrificing reliability, and is comfortable being fully responsible for the technical side of a direction.
Key Responsibilities:
Implement and launch A/B experiments across the funnel (landings, quiz, paywall, checkout) from specs and Figma layouts — correct bucketing, clean tracking, zero regressions.
Own our Stripe and Solidgate integrations (checkout, subscriptions, webhooks, upsells) and integrate new services as we test them.
Develop the internal admin panel; maintain the support site on the same stack (forms, CSAT surveys, upcoming knowledge base).
Test before production, keep the revenue path relible, and when something breaks — find the root cause yourself via Amplitude, Sentry, logs, and the database.
Proactively improve code quality, performance, and delivery speed.
Requirements:
3+ years of commercial full-stack development with TypeScript.
Strong experience with a modern SSR framework — Astro or Next.js.
Production experience with payment systems (Stripe, Solidgate, or comparable): checkout, subscriptions, webhooks, idempotency, edge cases.
Web2app / quiz funnels / subscription products: paywalls, upsells, trials.
Experience with serverless deployments (Vercel or similar) and PostgreSQL.
Understanding of the technical side of A/B testing: consistent bucketing, no flickering, clean event data.
Independent full-stack debugging and a habit of testing before shipping.
English at Intermediate+ level.
Nice to Have:
Attribution & pixels: Meta/TikTok pixels, server-side events, AppsFlyer/OneLink, deep links.
Experimentation platforms (GrowthBook, Statsig, or similar).
Amplitude for user-level debugging; Tailwind CSS and pixel-perfect Figma implementation.
Experience in fast-growing startups or lean, high-velocity teams.
Tech Stack:
Core: TypeScript · Astro · Tailwind CSS · Zod
Infrastructure: Vercel (Serverless) · Neon (PostgreSQL)
Payments: Stripe · Solidgate
Experiments & Growth: GrowthBook · custom experiments admin · Amplitude
Stability: Sentry · Vitest
Waiting for your CV!