Cloudflare launches Precursor, a client-side JavaScript system that detects bots by analyzing mouse movements, behavioral patterns across user sessions; runs on enterprise sites processing 3 billion verifications daily to distinguish human traffic from automated agents with reduced friction.

Introducing Precursor: detecting agentic behavior with continuous client-side signals

2026-07-135 min readBot mitigation is an adversarial game: attackers adapt, defenders respond, and the cycle continues. At Cloudflare, we stay ahead by combining visibility across our global network with signals from the client-side environment. At the network level, we analyze over 1 trillion requests per day to understand reputation, patterns, and anomalies across more than 20% of the web. On the client side, we’ve pushed detection deeper with Cloudflare Turnstile, which has evolved from a CAP...