Composal, a London-based startup in Y Combinator's Fall 2026 batch, sells swarms of browser agents that use software the way customers would and report bugs back to coding agents. Pricing starts at $500 for 3,000 browser minutes, according to the company's documentation.
The pitch rests on a simple imbalance: AI coding agents can ship features faster than human teams can check them. Composal wants to own the checking.
"In conversations with customers and other engineering teams, we keep coming back to the same question: when an agent says a feature is done, how do you know it works?" founder Pandelis Zembashis wrote in an Oct. 23 post on the company's Reflog blog.
How the product works
Composal's homepage says it "sends a swarm of agents to use your product like your users do." The tagline is blunter: "Your agents build it. Ours break it."
The product, called Verify, runs browser agents against a managed shadow environment or any HTTP(S) URL, per the docs. The agents operate in a sandboxed browser and, the docs say, do not edit source code. Each finding comes back with video, logs and steps to reproduce.
The company's pages divide Verify into four parts:
- Discovery reads specs and a connected code repository, then builds a persistent map of screens and user flows.
- Deep Scan sends a focused swarm to pressure-test a feature or reproduce a specific bug.
- Scenarios turn user journeys into repeatable YAML tests. Verify selects relevant scenarios for each pull request diff, or runs full packs on a schedule.
- CLI lets teams run QA from inside a coding agent.
Checking the checker
An automated tester that cries wolf is worse than none, and Composal appears aware of it. Its verification docs say a separate model re-checks Deep Scan findings, and that the most serious bugs, labeled P0 and P1, are re-run in a fresh browser before being confirmed. Runs are pinned to an exact environment revision and scenario pack, with video, screenshots, console output and network data captured.
