Sparky*
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Build state-of-the-art AI-powered products with us.
Where hard problems, clean engineering, and real impact meet.
Join Sparky*
All levels (Junior – Senior) · Remote / Hybrid
Split / Zagreb / Milan

Position:
Senior Backend JavaScript
developer

You'll build backend services that turn bold ideas into working products.

We’re looking for Senior Backend JavaScript Developers to help us ship our AI platform. You’ll design Node.js and NestJS services, model the data behind them, and work with a team that values clarity, craft, and delivery.

Backend Product Development

Own features end to end, from API contract to database schema to what runs in production. You'll write TypeScript services in NestJS, model data with MikroORM and PostgreSQL, and expose clean, typed endpoints the frontend can build on with confidence.

Clean, Typed APIs

Design REST endpoints with contracts that hold. Validation at the boundary with Zod, predictable error shapes, and versioning that doesn't break the clients you already have.

Solid Data Modelling

Entities, relations, migrations, and queries that stay fast as tenants grow. PostgreSQL and MikroORM, with indexes and transactions chosen on purpose, not by accident.

Reliable API Foundations

Authentication with Auth0 and JWT, permission checks on every route, background jobs on BullMQ and Redis, and logging good enough to debug a live incident.

Ship Together

Work in short cycles with frontend, design, and infrastructure in the same room. Review each other's pull requests, agree the contract before the code, and keep the develop branch deployable.

Quality, Proven

Unit and integration tests for the logic that matters, CI green before merge, and features that behave the same in staging as they do for the first customer who opens them.

You’ll work alongside senior colleagues on innovative projects, across AI, data, product, and delivery, shipping work that reaches users while leveling up every week.

Mentorship & code reviews

Honest feedback loops

Real ownership, real impact

Quality as a default

Modern tools, real scale

HOW WE WORK

Grow fast,
on innovative projects.

0 Impact
Real users, real constraints
0 Scale
Systems built to scale
0 Deep Tech
State-of-the-art projects
0 Career
Mentorship + real ownership
LET’S BUILD

Build the next thing

You’ll grow by doing the work that matters: innovative and deep tech projects and real data. We move fast, mentor actively, and ship things that hold up outside the demo.