Fullstack Engineer
Posted 4 Jun 2026
Advertised as “Senior Fullstack Engineer”
BranchFactor Summary
The original posting with the fluff stripped out
- Expected experience
- 4+ yrs
- Management level
- Individual contributor
- Employment
- On-Site
- Contract
- Full-time
No salary listed for this role.
The AI Operating System for Private Capital.
Capsa
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
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Role: Senior Fullstack Engineer
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Location: London, UK (Hybrid, in-person 4 days per week)
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Team: Engineering
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Compensation: Top of market. Competitive base + OTE
The role
Own product features and take them from ideation to production and measure the impact. Work across all layers of the application to deliver value for our customers. Uphold the quality of our codebase and find ways to move faster.
The opportunity
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Ownership: You'll own whole surfaces of the product end to end. You'll make the architecture calls, ship them, and operate them.
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Growth: You'll work across the entire stack, alongside a team of startup veterans, and take on real responsibility.
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Upside: You'll receive meaningful equity in a company that grew 15x last year.
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Impact: You'll leave an indelible mark on an industry responsible for ~7% of US GDP.
Recent projects include
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Agent Harness: Our own agent harness built on a custom, streaming-first graph execution framework.
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Code Execution Framework: Our own code execution framework that can be interrupted and resumed mid-execution for programmatic tool calling.