JA4 TLS Fingerprint

Your client's TLS ClientHello fingerprint, as seen by this server.

Your JA4 fingerprint

t13d1011h2_61a7ad8aa9b6_3fcd1a44f3e3

JA4 string: t13d1011h2_61a7ad8aa9b6_3fcd1a44f3e3

JA4_r (raw, unhashed): t13d1011h2_00ff,1301,1302,1303,c02b,c02c,c02f,c030,cca8,cca9_0005,000a,000b,000d,0017,0023,002b,002d,0033_0503,0403,0807,0806,0805,0804,0601,0501,0401

How each part is computed

JA4_a — the human-readable part

Built by concatenating 6 fields directly from the ClientHello. No hashing — you can read it.

1 · Protocol

t — TCP (TLS). t = TLS over TCP, q = QUIC, d = DTLS.

2 · TLS version

13 — TLS 1.3. Highest version from supported_versions (ignoring GREASE), or the legacy version field if the extension is absent. Possible values: 13, 12, 11, 10, s3, s2, 00.

3 · SNI

d — domain (SNI extension present). d = SNI extension present (domain), i = no SNI (IP).

4 · Cipher suite count

10 — cipher suites, zero-padded to 2 digits and capped at 99. Only GREASE values are excluded; SCSV (0x00FF, 0x5600) and reserved/experimental values (0xFE00–0xFEFF) are counted.

5 · Extension count

11 — extensions, zero-padded to 2 digits and capped at 99. Only GREASE values are excluded — SNI (0x0000) and ALPN (0x0010) are counted here, even though they are removed from the JA4_c hash below.

6 · ALPN

h2 — first and last alphanumeric characters of the first ALPN value ('h2'); if the first or last byte is non-alphanumeric, the first and last characters of the ALPN's hex encoding are used instead. 00 means no ALPN extension; otherwise it's the first and last alphanumeric characters of the first ALPN value (e.g. h2 for HTTP/2). If the first or last byte of the first ALPN is non-alphanumeric, the first and last characters of the ALPN's hex encoding are used instead.

Result

Concatenate them in order: t13d1011h2 = t13d1011h2

JA4_b — cipher suites hash

1 · Collect

Take all cipher suites from the ClientHello and remove GREASE values.

2 · Sort & format

Sort ascending, format as comma-separated 4-char lowercase hex: 0x1301,0x1302,…

3 · Hash

SHA-256 the string and take the first 12 hex characters. SHA-256("0x00ff,0x1301,0x1302,0x1303,0xc02b,0xc02c,0xc02f,0xc030,0xcca8,0xcca9")

Result

61a7ad8aa9b6

JA4_c — extensions + signature algorithms hash

1 · Collect extensions

Take all extensions, remove GREASE values, and also remove SNI (0x0000) and ALPN (0x0010) — those are already captured in JA4_a.

2 · Sort extensions

Sort the remaining extensions ascending and format as 4-char lowercase hex.

3 · Append signature algorithms

Append the signature algorithms in their original order (not sorted), separated from the extensions by an underscore: exts_sigalgs.

4 · Hash

SHA-256 the resulting string and take the first 12 hex characters. SHA-256("0x0005,0x000a,0x000b,0x000d,0x0017,0x0023,0x002b,0x002d,0x0033_0x0503,0x0403,0x0807,0x0806,0x0805,0x0804,0x0601,0x0501,0x0401")

Result

3fcd1a44f3e3

Final assembly

Join the three parts with underscores: t13d1011h2_61a7ad8aa9b6_3fcd1a44f3e3

Raw ClientHello data

Connection

TLS version 0x0304 · TLS 1.3

SNI shigshag.com

ALPN h2http/1.1

Cipher count 10

Extension count 11

Cipher suites · sorted ascending, GREASE filtered

0x00ff0x13010x13020x13030xc02b0xc02c0xc02f0xc0300xcca80xcca9

Extensions · original order, GREASE filtered, includes SNI/ALPN

0x00000x00170x002d0x00330x00100x000d0x00050x002b0x000b0x00230x000a

Signature algorithms · original order

0x05030x04030x08070x08060x08050x08040x06010x05010x0401

JA4 fingerprinting designed by FoxIO.