JA4 q13d0315h3_55b375c5d22e_e2bb28c9b3a4

q13d0315h3_55b375c5d22e_e2bb28c9b3a4

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

15

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 15

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

Named groups 4

• x25519
• secp256r1
• secp384r1
• secp521r1

771,4865-4867-4866,16-43-34-27-23-13-28-10-65281-0-51-45-5-57-65037,29-23-24-25,

Seen in live traffic

Connections

2

First seen

2026-10-14 08:33 UTC

Last seen

2026-10-20 08:39 UTC

Transport

QUIC

JA3 hashes absorbed

2

The same client, 2 different JA3s

This one JA4 covers 2 distinct JA3 hashes. A JA3 hashes the cipher and extension lists in the order they arrived, so a client that shuffles them — which Chrome and its derivatives do on purpose — produces a new JA3 almost every connection and fragments into what looks like 2 unrelated clients. JA4 sorts those lists before hashing, which is why all of it lands here instead.

• 99c15e42d33091e6fc31fdb650d7c9b7
• 866fa537968f272df221ec77bcc5bce5

User-Agents seen on this fingerprint

• Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:158.0) Gecko/20100101 Firefox/158.0 4×

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.