Staff Software Engineer

About the role

We're looking for a Staff Engineer to define the architecture of an AI-native accounting software that replaces traditional management systems.

Salary €70,000 – €90,000 + 0.2 – 0.4% equity.

Milan, hybrid 3+2.

Fluent Italian is a must-have: we work closely with Italian accountants.

👥 Who we are

We're a team of 5: the founding team (CEO, COO, CTO) + our first two employees (Marketing and Data Engineer). We've raised the funds we need to build, and we're aiming for 10 people on the product team by the end of 2026.

You're the fourth hire on the technical team and the first with an explicit architecture mandate: you define the foundations we'll build on for the next 5 years.

🎯 The context

We're not building a management system: we're building the deterministic half of an AI-native system. The agents propose, your services validate. Business invariants that hold across thousands of companies. Accounting operations that are architecturally impossible to get wrong.

As a Staff Engineer you're the technical reference point for the team. You don't just write code — you define the rules of the game: how we model the domain, how we design APIs to be consumed by autonomous agents, how we guarantee isolation between tenants, how we capture every system decision for the audit trail.

🏗️ The architectural challenges

- Accounting domain modeling — double-entry, multi-currency, journal entry immutability, accrual-based tax state. Correctness is non-negotiable.

- Agent-first API design — structured responses, explicit error boundaries, stable contracts an LLM can consume reliably. Not generic REST: APIs designed to be reasoned about by a machine.

- Multi-tenant isolation at scale — zero context leakage across thousands of companies. RLS, credential scoping, tenant-aware middleware.

- Event sourcing and audit trail — every accounting action is immutable, reversible only through counter-entry. The log is the truth.

- Observability for AI — capturing the full decision context of every agentic action: input, output, reasoning, system state at the moment of the decision.

✅ What we're looking for — must have

- 7+ years of backend engineering in production on complex systems

- Documented experience of architectural ownership (you've made decisions that still hold today)

- Python, Go, Java or similar statically-typed languages — real mastery, not familiarity

- Advanced PostgreSQL: transactions, constraints, indexing, query optimization, data modeling

- Distributed systems: idempotency, eventual consistency, failure modes, retry semantics

- Fluent Italian (domain communication with accountants happens in Italian)

- Ability to transfer architectural decisions to the team clearly — written and verbal

➕ Nice to have

- AI/LLM systems: inference, RAG, agent orchestration, evaluation frameworks