Full-Stack Software Engineer (Growth) Amsterdam

firsty.app; Amsterdam; On-site; EUR 39,000 - 84,000; Full time

Job summary

Firsty.app in Amsterdam is seeking a growth-focused full-stack engineer who owns the product end-to-end. You will ship features for the developer portal, SDKs and docs, enabling partners to go live with minimal friction, while using AI tooling to accelerate delivery.

You will instrument funnels, analyze activation and retention, and own the surface from design to measurement. Experience across the stack and comfort shipping solo are essential.

Qualifications

• Ship fast with full-stack ownership and minimal guidance.
• Experience building developer portals, docs, and SDKs.
• Ability to instrument funnels and drive activation and retention.

Responsibilities

• Own builders.firsty.app and the developer portal and docs.
• Ship features to reduce friction for partners with speed and quality.
• Instrument funnels, analyze drop-offs and drive improvements.
• Own the developer experience end-to-end from design to measure.

Skills

React

Node.js

Go

AI tooling

Tools

Claude Code

SDKs

Job description

Your north star is simple. Make our B2B engine feel like Stripe. A partner should be able to land on our site, read the docs, grab an SDK and go live on their own, without a single sales call. Fully self-serve.

Role Overview

This role is basically running your own company inside Firsty. You own the design, the front end, the back end and the growth, all of it. We do not care how many years you have. We care that you ship. If you build whole front ends with Claude Code and move faster than a team of three, you are exactly who we want. Nobody hands you a spec. You decide what to build, you ship it, and you own the number it moves.

What you own

builders.firsty.app, our developer portal and docs. You make it so a partner in the UK or Germany goes from curious to integrated with as little friction, and as few sales calls, as possible.

The growth loops in the app: referrals, sharing, activation, onboarding. The mechanics that make every new user bring the next one.

Developer experience end to end: SDKs, sample code, API ergonomics, sandbox flows. Easy integration means faster deals.

The numbers behind it. You instrument the funnels, find where users and partners drop off, and fix it.

Who you are

You ship, fast. You build full-stack with modern tools, and you use AI like Claude Code to move at the speed of a small team on your own.

Comfortable across the stack: React on the front end, a modern back end like Node or Go. Years do not matter, output does.

A growth head. You care about activation, retention and conversion, and you can read a metric and form a hypothesis.

You own a surface from design to build to measure to iterate, without anyone holding your hand.

You make technical products feel easy: good docs, clean APIs, real developer empathy. Stripe is the bar.

What We Offer

€3,500 to €7,500 gross per month, depending on experience.

The honest bit

You are the growth engineering team, not part of a big one. Huge ownership, nobody to hide behind.

The B2B funnel barely exists yet. You are building it, not tuning it. If you want a narrow ticket queue and a review on every PR, this is the wrong role.