Phoebe: Building an immune system for software

An AI start‑up from London is trying to make software failures a thing of the past.

Phoebe raised $17 m (~£12.6 m) in one of the UK’s largest seed rounds this year. The round was co‑led by GV (Google Ventures) and Cherry Ventures.

Founders Matt Henderson and James Summerfield previously ran Stripe Europe and sold their earlier start‑up Rangespan to Google. They say modern apps waste developer time and money - 40 million developers spend 30 % of their time firefighting bugs, and outages cost companies $400 billion last year.

Phoebe’s pitch: deploy swarms of AI agents that continuously monitor live system data, identify and triage errors, and then generate the code and infrastructure changes needed to fix them.

The team calls it a “software immune system,” a layer that sits above monitoring tools and reduces fix times by up to 90 %. GV partner Roni Hiranand says the approach adds contextual intelligence to prevent AI‑generated bugs from spiralling.

Customers already include Trainline, where Phoebe’s platform has cut incident investigation time from hours to minutes.

The funding will let Phoebe scale engineering, expand go‑to‑market efforts and broaden customer reach.

The company plans to invest heavily in AI research to ensure its agents can keep pace with ever‑more‑complex AI codebases. Investors hope that if Phoebe’s AI immune system works, it could become a standard layer in the modern software stack.