Senior / Staff Software Engineer (New Product) - Greenstep Espoo

Do you want to build something new from the first commit, with people who hold the bar as high as you do? We are a small senior team building a new product that has not been announced yet, and we are looking for one more engineer at the same level. Greenstep is a Finnish, family-owned growth company founded in 2010 that provides high-quality technology and back-office services to support its clients' growth and success. Today we are a community of more than 800 experts working in the Nordics and across Europe. We have grown organically, and today Greenstep has people in Finland, Åland, Sweden, Norway, Estonia, Denmark and the Netherlands. We share one goal: to help growth companies become leaders in their fields. Alongside our services we build our own software. BI Book already serves thousands of clients in several countries, Bezala 100t+ active users and several other good success stories. Now we are building our next product, and we are hiring the people who will build it. The Role You join a small team building a new multi-tenant SaaS product from day zero. We cannot say much publicly yet. We will tell you everything in the first conversation. What we can say now: The stack is modern and deliberate. Go for the deterministic core, Python for AI and reporting services, React and TypeScript on the front end, Postgres with row-level security underneath, and an event-driven architecture. We are spec driven. Every feature gets a product spec and a build spec before code. Schema changes ship with documentation. Decisions become architecture decision records. Correctness is non-negotiable. The product works in a domain where every change must be exact and auditable. Tests and reviews are not optional. AI is part of the workflow. You will use AI coding agents every day and hold their output to the same standard as any other code. As a Staff Software Engineer you will: You will own the architecture of the system, not just the services in it. You set the boundaries between services, the contracts between them, and the failure model that holds when one of them is down. You'll design and build services end to end, from schema to API to tests to production, across the Go core and the Python layer. This is a hands-on role and stays hands-on. You will own the multi-tenancy model. Tenant isolation, data residency, noisy-neighbour behaviour and the blast radius of any single tenant are your call, and you make that call explicit in writing. Own the data layer's long game. Schema design, partitioning strategy, and a defensible answer to when the system needs to scale horizontally and what it costs when it does. Own how the system runs. Kubernetes topology, resource and scaling behaviour, rollout and rollback strategy, and the observability that makes an incident diagnosable in minutes rather than hours. Turn specs into working software and push back on the specs when they are wrong. Raise the bar for everyone. You review other people's work, write the decision records the team argues with, and make the engineers around you better. At this level your impact is measured through the team, not only through your own commits. Shape the product. In a team this size your view on architecture and direction carries real weight. Greenstep works in a hybrid model: at least 50% of working time is at the office. What We're Looking For You are a hands-on staff engineer who has owned a distributed production system from design to operation, carried the pager for it, and lived with the consequences of your own architecture decisions. You want to do it again on a clean slate. You are precise about details, you see the whole system, and you can explain your reasoning in writing well enough to change other people's minds. What we expect you to bring: 10+ years building production backend systems, including several years operating them, not only shipping them. Distributed systems in depth. You have designed and run services that communicate across a network and you are fluent in what that costs: partial failure, retries and idempotency, ordering and exactly-once claims, consistency trade-offs, and backpressure. You can explain a real outage you caused or fixed and what you changed afterwards. Multi-tenant SaaS in depth. You have designed a tenant isolation model and lived with it. You have clear opinions on shared-schema versus schema-per-tenant versus database-per-tenant, how tenant context is carried and enforced end to end, and how you keep one tenant from degrading everyone else. Deep Postgres. Schema design, indexing, query planning, transactions and isolation levels, connection pooling, locking and long-running migrations on live tables. Row-level security for tenant isolation is a strong plus. Postgres at scale. Declarative partitioning and a worked understanding of horizontal scaling: read replicas, logical replication, tenant placement and rebalancing, cross-shard queries and the operations they break. What matters most to us is the j