JA4 fingerprint
t13i880900_fcb5b95cb75a_b0d3b4ac2a14
SoftEther VPN - infrastructure / agent software.
TCP · TLS 1.3, no SNI (IP), 88 cipher suites, 09 extensions, none offered ALPN.
Anatomy
fcb5b95cb75a is a SHA-256 of the sorted cipher list · b0d3b4ac2a14 covers the extensions and signature algorithms. Hashes aren't reversible - the identity below comes from matching them.
Identity
from FoxIO ja4dbSoftEther VPN is the published identity for this exact fingerprint in FoxIO's ja4db - a known mapping, not a guess.
SoftEther VPN client handshake, connecting without SNI.
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connection_fingerprint: {ja4: {hash: "t13i880900_fcb5b95cb75a_b0d3b4ac2a14",family: "unknown",},user_agent_alignment: "?", // needs a live requesth2_fingerprint: "?", // needs a live request}
A JA4 is one clue. Foil checks hundreds more - the network, the device, and how the session behaves - and tells you when they don't add up. That's usually where the bots are.
See it on a real session - free →What to do
ReviewLegitimate in the right place, suspicious out of it - decide by context. A VPN or remote-access stack hitting an admin panel, corporate SSO, or a consumer signup flow deserves scrutiny.
Check it against an allowlist of sanctioned infrastructure; if it isn’t sanctioned, step up verification or block. VPN/proxy egress also hides the real client, so pair this with IP intelligence (datacenter vs residential, known-VPN ranges) and watch for many accounts sharing one exit.
About this fingerprint
SoftEther VPN client handshake, connecting without SNI.
The breakdown above is computed from the string itself: the readable JA4_aprefix gives the transport, TLS version, SNI flag, cipher and extension counts, and ALPN, while the two hashes are matched against Foil's reference database to name the client. For the full background, see TLS fingerprinting, or try any fingerprint of your own in the JA4 database.
Both component hashes can be looked up on their own: cipher hash fcb5b95cb75a lists every fingerprint built on this cipher stack, and extension hash b0d3b4ac2a14 lists the variants that share this extension set.
Frequently asked
JA4 is a fingerprint of the TLS ClientHello a client sends before any HTTP. It is a three-part string, JA4_a_JA4_b_JA4_c: a readable prefix (transport, TLS version, SNI, cipher and extension counts, ALPN) followed by two truncated SHA-256 hashes over the sorted cipher and extension lists. Unlike JA3, it survives Chrome's extension-order randomization.
The JA4_a prefix decodes by eye: the first character is the transport, the next two are the TLS version, then SNI, a two-digit cipher count, a two-digit extension count, and the first ALPN value. The two hashes are not reversible; you identify them by matching against a database or by decoding the raw (JA4_r) variant.
A JA3 fingerprint is an MD5 hash of the handshake, so the hash itself carries no readable structure. Only the raw JA3 string (version, ciphers, extensions, curves, point formats) can be decoded back into its components.
Yes. Fingerprints are matched against a distilled reference database of common browsers, HTTP libraries, and automation tools. The match tells you what a client is; identifying whether it is lying about that requires cross-checking against the User-Agent, HTTP/2 fingerprint, and JavaScript environment in a live request.