Senior Fullstack Engineer

Moonfire; España; Remote; EUR 100,000 - 150,000; Full time

Benefits offered by this job

Latest technologies

Direct user feedback

Small founding team

Open-source involvement

Travel opportunities

Learning budget

Flexible hours

Competitive salary

Health insurance

Job summary

Moonfire is a small, fully remote team of senior engineers building Lingo.dev tools used by developers worldwide. You will design, develop, and scale web applications, open source tooling, and robust APIs with a focus on performance and UX.

We value CS craft, remote collaboration, and ownership of features end-to-end. You’ll work across frontend, backend, and integrations while collaborating with founders and a distributed team.

Qualifications

• 5+ years of production experience with TypeScript and Node.js.
• Expert React knowledge with Suspense-first patterns, skeleton loaders, loading states.
• Experience with SSR, CSR, and SSG.
• Deep expertise with React routing libraries.
• Built or contributed to design systems / component libraries used by others.
• Experience designing navigation, onboarding flows, and user journeys.
• Backend experience with Node.js (Express.js or similar) and PostgreSQL.
• Experience designing production-ready APIs.
• Experience with authentication and authorization systems.
• CS degree or equivalent - algorithms, data structures, system design.
• Prior remote work experience in distributed teams.
• Available 7-10am San Francisco time daily.
• Fluent English
• Deep knowledge of AI coding tools and workflows.

Responsibilities

• Take full ownership of features from design to deployment: draft technical designs, review with founders + the team, implement end-to-end with tests and documentation.
• Develop and grow Lingo.dev products across web apps, CLI, and backend APIs.
• Collaborate on 3 sprint roadmap cycles and one cooldown sprint per cycle.
• Participate in weekly Demo Days with the team.

Skills

TypeScript

Node.js

React

SSR/CSR/SSG

React Router / TanStack Router

Design systems

Navigation design

API design

Auth systems

CS degree or equivalent

Remote work experience

U.S. time overlap

Fluent English

AI tooling

Education

CS degree or equivalent

Tools

PostgreSQL

Job description

About the Project & Team

We started Lingo.dev at a hackathon and, after winning the best dev tool award, we just kept building. It evolved into a developer-loved toolkit with hundreds of active users, 7,000 weekly CLI runs, 5,000 GitHub stars, and over 100 million translated words. We've graduated from the world's best tech accelerator (Y Combinator) and raised venture funding to continue building developer tools that must exist but don't yet.

We're a small, fully remote team of senior engineers who like to work hard on interesting problems. We value computer science craft over corporate politics and love building tools for developers - including ourselves. Recently we started getting more feature requests than we can ship, so we're excited to expand the team.

Job Functions

• As part of a team of senior engineers, design, develop, and grow the Lingo.dev products

  • Web applications - Routing, navigation, onboarding flows, user experience, performance

  • Open source tools - CLI, webpack/vite plugins

  • Backend APIs - encapsulation, API design, security

  • Database layer (PostgreSQL)

  • Integrations - with 3rd party systems

  • AI agents

• Take full ownership of features from design to deployment: draft technical designs, review with founders + the team, implement end-to-end with tests and documentation

• 3 sprints of product roadmap work, 1 cooldown sprint (customer feature requests, improvements, bug fixes)

• Weekly Demo Days with the rest of the team

Requirements

• Built an own app, or side project that others have used - could be a tool for a friend, a small product, an open-source package, anything real people relied on

• 5+ years of production experience with TypeScript and Node.js

• Expert React knowledge - Suspense-first patterns, skeleton loaders, loading states

• Experience with SSR, CSR, and SSG

• Deep expertise with React routing libraries

• Built or contributed to design systems / component libraries used by others

• Experience designing navigation, onboarding flows, and user journeys

• Backend experience with Node.js (Express.js or similar) and PostgreSQL

• Experience designing production-ready APIs

• Experience with authentication and authorization systems

• CS degree or equivalent - algorithms, data structures, system design

• Prior remote work experience in distributed teams

• Available 7-10am San Francisco time daily

• Fluent English

• Deep knowledge of AI coding tools and workflows - you use them daily and know how to get the most out of them

Optional Skills

• Experience with Cloudflare platform (Workers, etc.)

• Experience with Row-Level Security (RLS) in Supabase/PostgreSQL

• Experience with background job workflows

• Built an AI agent before

• Contributed to a design system or React component library used by other teams

• Experience with observability and monitoring

• Open source contributions

• Speaking multiple languages is a plus

• You love Remix, React Router, TanStack Router, or TanStack Start

Benefits

• Opportunity to work with latest, cutting-edge technologies

• Work directly with users using what you build every day

• Small team working directly with founders

• Be a part of open-source community

• Occasional travel to meet the team in person

• Conference and learning budget

• Flexible working hours

• Competitive salary

• Health insurance

Interview Process

1. Screening Call (Technical/Cultural Fit)

2. Live Coding / Technical Project: Evaluating CS fundamentals and architectural depth (algorithms, system design)

3. Final Deep Dive (System Design & Partnership)

After passing the interviews, there's a one-month paid trial period. It's intense - we'll work closely together on real features to make sure we work well together.

Do Not Apply If

• You are looking for passive, hands-off remote work with minimal team interaction

• Uncertainty makes you uncomfortable - you prefer detailed specs over figuring things out as you go

• You are unwilling to prioritize customer needs over your preferred patterns or tools