Full-Stack Web Developer (TypeScript)

Job description

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!