AI-First Full-Stack Engineer - Back-End

LeanTeams; Polska; On-site; PLN 180,000 - 240,000; Full time

Job summary

LeanTeams is hiring a Full-Stack Software Engineer with a backend focus to join our early-stage Agentic Research SaaS. You will build reliable, scalable backend services, own technical decisions, and ship complete features end-to-end.

You will work with Node.js, TypeScript, PostgreSQL, Fastify, and modern frontend tech to deliver AI-powered research tooling for researchers and knowledge workers.

Qualifications

• Back-end systems in production experience required.
• Strong API design and relational database experience.
• Experience with Node.js and TypeScript preferred.
• Ability to handle data integrity and reliability challenges.
• Front-end experience to ship features end-to-end.
• Clear communication and problem-solving skills.
• Familiarity with AI development tools is a plus.

Responsibilities

• Build reliable, scalable backend systems and APIs.
• Own technical decisions and drive end-to-end features.
• Collaborate with a small engineering team to ship product features.

Skills

Back-end systems

APIs

Relational databases

Node.js

TypeScript

Front-end experience

Independent judgment

Communication

AI development tools

Tools

Node.js

TypeScript

PostgreSQL

Fastify

SvelteKit

Tailwind

Playwright

Job description

LeanTeams is hiring a Full-Stack Software Engineer with a backend focus to join our early-stage Agentic Research SaaS. You will build reliable, scalable backend services, own technical decisions, and ship complete features end-to-end.

You will work with Node.js, TypeScript, PostgreSQL, Fastify, and modern frontend tech to deliver AI-powered research tooling for researchers and knowledge workers.