JA4 fingerprint
t12d350600_9d4c96c0953b_0a9c83bf8b96
Philips Hue Bridge - an IoT / embedded device.
TCP · TLS 1.2, domain present, 35 cipher suites, 06 extensions, none offered ALPN.
Anatomy
9d4c96c0953b is a SHA-256 of the sorted cipher list · 0a9c83bf8b96 covers the extensions and signature algorithms. Hashes aren't reversible - the identity below comes from matching them.
Identity
from FoxIO ja4dbPhilips Hue Bridge is the published identity for this exact fingerprint in FoxIO's ja4db - a known mapping, not a guess.
Philips Hue smart-home bridge - an embedded TLS 1.2 IoT stack.
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connection_fingerprint: {ja4: {hash: "t12d350600_9d4c96c0953b_0a9c83bf8b96",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
ContextExpected only from the device talking to its own cloud - it should essentially never appear on a human-facing web flow.
A smart-bulb, printer, or thermostat JA4 behind a browser User-Agent on your login or checkout page is a strong spoofing signal: flag or block it. If you run the fleet, allowlist these fingerprints for the device’s own endpoints and alert if they appear anywhere else.
About this fingerprint
Philips Hue smart-home bridge - an embedded TLS 1.2 IoT stack.
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: extension hash 0a9c83bf8b96 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.