Senior FastAPI Developer

Newcode.ai; Stockholms kommun; On-site; SEK 80,000 - 100,000; Full time

Benefits offered by this job

Drive innovation in AI

Collaborative team environment

Shape product and culture

Flexible English-speaking environment

Job summary

Newcode.ai is seeking an experienced backend developer to own and enhance the backend for our AI features. Responsibilities include designing APIs, ensuring reliability in async processes, and integrating with existing client systems.

The ideal candidate will have extensive experience with backend systems, strong knowledge of Python and FastAPI, and a commitment to data security. Join us in shaping innovative AI products within a dynamic team environment.

Qualifications

• 7+ years building backend systems that run in production.
• Experience with real LLM-powered systems.
• Strong understanding of AI coding tools and their implications.

Responsibilities

• Design and build APIs and services our products run on.
• Work on AI plumbing: retrieval, orchestration, tool-calling.
• Ensure reliability in async and distributed work.
• Build integrations with client systems for document processes.

Skills

Backend systems development

API design

Data security

AI coding tools

Distributed systems

Tools

Python

FastAPI

PostgreSQL

Redis

Job description

Who are we?

We build AI tools for firms in legal and professional services: software people use for real work, not demos. We started a few months ago and already have paying clients who rely on what we ship. The team is small and moving fast.

The role

You'll own the backend behind our AI features. That's the APIs, the data pipelines, and the orchestration sitting between our product and the language models doing the work. In practice it means running retrieval over large sets of documents, getting dependable results out of LLMs and their tool calls, streaming responses to the UI, and processing long jobs in the background without things falling over. It isn't CRUD work. The hard parts here are keeping AI systems accurate and fast with confidential data, at production scale. You'll make architecture calls early and live with them.

What You'll Do

• Designing and building the APIs and services our products run on.
• Working on the AI plumbing: retrieval, orchestration, tool-calling, response streaming, and the evals that tell us whether the output is any good.
• Keeping async and distributed work reliable: document ingestion, embeddings, and long-running jobs on Redis.
• Building integrations with the systems clients already use, like email and document stores, and making them hold up under load.
• Taking data security and isolation seriously, since clients hand us confidential material.

Who You Are

• At least seven years building backend systems that run in production. Depth matters more to us than the number.
• You think about how things fail, not just how they behave when everything's fine.
• You've built real LLM-powered systems, or you're itching to: RAG, tool-calling, agents. You know where they tend to break.
• You use AI coding tools (Claude Code, Cursor, Copilot) and use them well. Faster output, but you understand and stand behind every line; you wouldn't approve sloppy AI-written code in review, so you don't ship it either.
• You're fine in a startup that changes direction. Decisions get made, then revisited.

Experience we expect with the stack

• Python: 6+ years
• FastAPI: 3+ years
• PostgreSQL / SQL
• Redis: 2+ years

Nice to have: RAG or vector search experience; LangChain or LlamaIndex; streaming over SSE, WebSocket or SignalR; Microsoft Graph and email integration work.

Benefits

• Be a driver of innovation in one of Oslo's most exciting AI ventures
• Work with talented peers in a collaborative, high-energy team
• Shape both product and culture as we grow
• Flexible, English-speaking environment