JA4

JA4 fingerprints clients from TLS and HTTP header order — harder to spoof than user agent strings, and one of the strongest signals for bot detection.

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What is JA4?

JA4 is a client fingerprinting technique that analyzes the structure and order of fields in TLS and HTTP headers. Unlike traditional methods that rely on user agent strings, JA4 examines how clients construct their requests, making it harder to spoof and more effective for identifying bots, malicious actors, and unique devices. It is widely used in security and fraud prevention.

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What is JA4?

A fingerprinting technique that analyzes the structure of TLS and HTTP headers to identify clients beyond user agent strings.

Bot Detection Techniques and processes used to identify and block automated software agents interacting with websites or applications.
TLS — Transport Layer Security & Bot Fingerprinting Transport Layer Security (TLS) is a cryptographic protocol that secures communication over computer networks.
User Agent A string sent by browsers or other clients to identify themselves and their capabilities to web servers.

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