JA4 t13d0912h2_f91f431d341e_ef7df7f74e48

t13d0912h2_f91f431d341e_ef7df7f74e48

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

What this fingerprint encodes

Transport

TCP

TLS version

TLS 1.3

Server name

server name sent

Cipher suites offered

9

Extensions offered

12

ALPN

h2

Same tool, different options

These 5 other fingerprints share this one's JA4_c — the extension and signature-algorithm hash. A client that keeps its extension set constant while varying its cipher list produces exactly this pattern, which is what a scanner iterating cipher suites looks like. A JA3 cannot show you this: its single MD5 collapses ciphers and extensions together, so every variation looks like an unrelated client.

• t13d181100_5d04281c6031_ef7df7f74e48
• t13d1412h1_3241d5e7d676_ef7df7f74e48
• t13d1712h2_5b57614c22b0_ef7df7f74e48
• t13d1812h1_5d04281c6031_ef7df7f74e48
• t13d1812ht_5d04281c6031_ef7df7f74e48

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 9

• TLS_AES_128_GCM_SHA256
• TLS_AES_256_GCM_SHA384
• TLS_CHACHA20_POLY1305_SHA256
• TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
• TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
• TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
• TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
• TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
• TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

Extensions 12

• server_name
• extended_master_secret
• renegotiation_info
• supported_groups
• ec_point_formats
• session_ticket
• application_layer_protocol_negotiation
• signature_algorithms
• key_share
• psk_key_exchange_modes
• supported_versions
• padding

Named groups 4

• x25519
• secp256r1
• secp384r1
• secp521r1

Point formats 1

• uncompressed

771,4865-4866-4867-49195-52393-49199-52392-49196-49200,0-23-65281-10-11-35-16-13-51-45-43-21,29-23-24-25,0

Seen in live traffic

Connections

3

First seen

2026-09-23 04:13 UTC

Last seen

2026-10-01 08:08 UTC

Transport

TCP

User-Agents seen on this fingerprint

• Mozilla/5.0 (compatible; YearAlertLeadFinder/1.0; +https://yearalert.com/bot) 2×
• Claude-User (claude-code/2.1.286; +https://support.anthropic.com/) 2×

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.