What is this tool?
Decode JA4 TLS fingerprint strings into TLS version, ALPN, and hash components.
How to use
Paste a JA4 string from tls.peet.ws or your client capture. Background: JA4+ spec (FoxIO).
JA4 Decoder
Decode JA4 TLS fingerprint strings into TLS version, ALPN, and hash components.
- TLS version
- TLS 1.3
- SNI
- SNI present
- Cipher count
- 15
- Extension count
- 16
- ALPN
- HTTP/2 (h2)
- Cipher hash
- 8daaf6152771
- Extension hash
- d8a2da3f94cd
- h2 in JA4 indicates ALPN negotiated HTTP/2, compare with Akamai H2 fingerprint separately.
- Cipher and extension hashes are truncated SHA256 digests of sorted TLS parameters (JA4 spec).