Senior Fullstack Engineer — AI-Driven, End-to-End Ownership

Siena AI; Helsinki; Remote; EUR 90,000 - 130,000; Full time

Benefits offered by this job

Equity or stock grants

Learning budget

Remote-friendly; async-first culture

Job summary

Siena AI in Helsinki is hiring a senior software engineer to own meaningful parts of our platform end to end, shipping reliable, high-performance systems that real brands depend on daily. You'll work closely with product to shape scope, make real architectural calls, and do your best work across frontend, backend, and infrastructure with an ownership mindset.

We value independent ownership, fast decision-making, and experience shipping LLM-powered features to production users in a distributed,

Qualifications

• 5+ years shipping and owning systems that are live in production.
• Strong in our core stack: Node.js, React, TypeScript, Express.
• You've shipped LLM-powered features to real users. This is a must, not a bonus.
• Solid with AWS (Fargate, Lambda, EC2, SQS), PostgreSQL, and Redis.
• Experienced with CI/CD pipelines and microservices.

Responsibilities

• Own features and systems across the full stack (frontend, backend, infrastructure) from problem definition through production.
• Partner with product to break down ambiguous scope and ship in iterative, high-impact releases.
• Make real architectural and design decisions in your area, and explain the reasoning so the team can build on it.
• Take cutting-edge language models into enterprise customer workflows, where reliability and safety actually matter.
• Solve hard engineering problems: API performance, microservices, scaling across channels and brands.
• Maintain and improve our AWS infrastructure with a DevOps mindset.
• Raise the bar around you. Share what you know, review thoughtfully, help teammates level up.

Skills

Node.js

React

TypeScript

Express

LLM features

AWS

PostgreSQL

Redis

Microservices

CI/CD

Tools

Next.js

CDK

Terraform

Python

Job description

Siena AI in Helsinki is hiring a senior software engineer to own meaningful parts of our platform end to end, shipping reliable, high-performance systems that real brands depend on daily. You'll work closely with product to shape scope, make real architectural calls, and do your best work across frontend, backend, and infrastructure with an ownership mindset.

We value independent ownership, fast decision-making, and experience shipping LLM-powered features to production users in a distributed,