JA4 Fingerprint Directory

q13d0313h3_55b375c5d22e_824790d21c68

Firefox — inferred from the User-Agent on its requests.

What this fingerprint encodes

Transport

QUIC

TLS version

TLS 1.3

Server name

server name sent

Cipher suites offered

3

Extensions offered

13

ALPN

h3

The hello it was computed from

Recovered because the proxy now stores the pre-hash JA3 string alongside the digest. Every number below came out of this client's ClientHello; anything we cannot name in the IANA registry is shown as its raw value rather than guessed at.

Version

TLS 1.2

Cipher suites 3

• TLS_AES_128_GCM_SHA256
• TLS_CHACHA20_POLY1305_SHA256
• TLS_AES_256_GCM_SHA384

Extensions 13

• encrypted_client_hello
• supported_versions
• server_name
• quic_transport_parameters
• psk_key_exchange_modes
• supported_groups
• signature_algorithms
• status_request
• application_layer_protocol_negotiation
• 34 (0x0022)
• record_size_limit
• compress_certificate
• key_share

Named groups 5

• SecP256r1MLKEM768
• x25519
• secp256r1
• secp384r1
• secp521r1

771,4865-4867-4866,65037-43-0-57-45-10-13-5-16-34-28-27-51,4588-29-23-24-25,

Seen in live traffic

Connections

1

First seen

2026-08-23 11:40 UTC

Last seen

2026-08-23 11:40 UTC

Transport

QUIC

User-Agents seen on this fingerprint

• Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:154.0) Gecko/20100101 Firefox/154.0 26×

A User-Agent is self-declared and trivially forged, so this names an observation rather than proving an identity. It is still the strongest signal available: the fingerprint comes off the TLS handshake and the User-Agent off the request that followed, and one client build keeping a stable JA4 while changing what it calls itself is a finding in its own right.

This entry is an observation, not a policy decision. It is here because the edge saw it, not because anyone reviewed it, and it blocks nothing on its own. Only the curated tier drives classification and banning.