Senior Fullstack Engineer

The AI Operating System for Private Capital.

Capsa AI

Private capital funds have to find potential investments, research and analyse them thoroughly, monitor them over time, drive improvements, and decide when to buy and sell. They've got to see through the marketing. They've got to outbid the competition. And they've got to learn from every deal they do. Historically, these processes have run on people, we are building the AI Operating System that will run them in the future.

We're focused, ambitious, and obsessed with building a category-defining company. In the last 12 months we've grown ARR 15x, achieved product–market fit with leading multi-billion-dollar PE firms, and expanded across the US, UK, and Europe. Now we're doubling down: we've raised a large Series A from top-tier VC investors to scale the team. We're hiring hyper-talented people who want to work at the forefront of AI and revolutionise an industry.

At a glance

• Role: Senior Fullstack Engineer

• Location: London, UK (Hybrid, in-person 4 days per week)

• Team: Engineering

• Compensation: Top of market. Competitive base + OTE

The role

Get on a fast track to owning features that sit at the heart of a platform used by the world's leading PE firms.

You'll work across the full stack - from backend infrastructure and data pipelines through to the AI layer and the interfaces analysts use every day. Whether you've built high-throughput data systems, worked on complex frontend products, or shipped across the stack at a fast-moving startup, you bring ownership most engineers don't have, and the job is to point that ownership at problems the industry has never had good tooling for.

This isn't a place to pick up tickets. We hire engineers who want to shape what gets built, not just build what they're told. Responsibility comes fast, scope grows with performance, and the founding team is close enough that your best ideas will get heard.

The opportunity

• Build features the industry has never had. Design and ship capabilities that give our platform genuine investment expertise; end-to-end, from data model to user interface.

• Own the full stack. Backend, infrastructure, AI integration, frontend. You move across whatever the problem needs, and you don't leave rough edges behind.

• Expand what the platform can do. Integrate new data sources, extend the agent loop, and increase the depth and breadth of analysis our customers can perform.

• Keep the codebase clean. Uphold rigorous standards across everything you ship. Tech debt is a tax on velocity, and you don't let it accumulate.

Recent projects include

• Agentic assistant with a finance-focused toolkit and advanced document authoring features

• Scalable document ingestion and indexing pipeline

• In-house, streaming-first agent framework

• AI-assisted document editor

Track record

• Engineering depth across the stack. Four or more years building production software at a venture-backed startup or top tech firm. Owning features end-to-end, not just one layer.

• You've shipped things that mattered. Entire products or features taken from ideation to production, with impact you can speak to. If you can't point to what changed because of your work, that's a flag.

• The right technical toolkit. Strong Python and TypeScript, backend infrastructure like FastAPI, Postgres, ElasticSearch, and RabbitMQ, a solid React frontend, and enough LLM exposure to work confidently across the AI layer, or close enough that the gaps close fast.

• Domain curiosity, not just technical ability. You go deep on the problem, not just the implementation. You care about what the product does for the person using it, and that shows in how you build.

• Comfortable at pace. Fast-moving environments are where you do your best work, not something you tolerate.

How you operate

• Low ego, high ownership. You want to be part of building something that matters more than you want a title that says so.

• Hungry and resilient. Start-up pace is the appeal, not the trade-off. Rejection doesn't slow you down.

• Bias for action over planning theatre. You move with incomplete information and adjust as you go.

• Genuinely curious about AI. Using it, breaking it, building it into how you work.

If this opportunity excites you

We'd like to meet you. Initial conversations are direct and substantive, going deep on the work, the team, and what you'd own in the first six months.

Capsa AI provides equal employment opportunities (EEO) to all employees and applicants for employment without regard to race, color, religion, sex, national origin, age, disability, genetics, sexual orientation, gender identity, or gender expression. We are committed to a diverse and inclusive workforce and welcome people from all backgrounds, experiences, perspectives, and abilities.

Capsa AI is committed to a fair and transparent hiring process. We confirm that this advertisement is for an active, existing vacancy within our organization. Please be advised that we may use artificial intelligence-driven tools to assist our recruitment team in screening, assessing, and selecting candidates for this position.