About Roook

Roook works on backends with an HTTP API. It looks for a sequence of valid requests that breaks a business rule, such as refunding more than was paid, and shows the result on the real running app.

• Finds: a deterministic, seeded search runs sequences of requests against your running app and checks every rule you approved after every step.
• Reproduces: a failing sequence is shrunk to a minimal one and replayed on the real app, 10 times by default. Results that do not repeat are reported as flaky. Each counterexample is saved as a JSON file plus a regression test.
• Verifies: a fix counts only if four engine checks pass: exact replay, your project's tests, the generated regression test, and a fresh search with a new seed.
• Keeps AI out of the verdict: IBM Bob's agents read the code, propose rules and write fixes. Only the deterministic engine decides whether a rule is broken or a fix is verified.

Backends that hold money, stock, permissions or state can break a business rule through a sequence of requests that are each valid on their own. In the shop-app example, buying for ₹100, then refunding ₹60 and ₹50, refunds more than was paid.

Tests cover the scenarios someone thought of, and a reviewer that says a bug might exist is only predicting. Roook runs the failing sequence and keeps it as a test, so the report is a proof.

Roook started at the IBM Bob 2.0 Hackathon in September 2026.

It has continued since as an independent product: in early access, open source under the MIT licence, built on IBM Bob, with the code on GitHub.

• Independent and founder-led: Roook is operated by Aayush Kumar as an individual and is not incorporated as a company. There are no employees and no outside funding.
• Free in early access: there are no paid plans, no billing, no team accounts and no SSO.
• Still being built: the roadmap lists what is limited today and what is planned.