---
title: tls.client.ja4
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/variables/client-connection/tls-client-ja4
---


The JA4 fingerprint computed from the TLS Client Hello packet as described in https://github.com/FoxIO-LLC/ja4/blob/main/technical_details/JA4.md.