Format Identifier
Paste any string to find out what it is: a JWT, JSON, a certificate, Base64, a URL, a cron schedule, a timestamp, a UUID, a hash or a set of file permissions. Then open it in the right tool with one click. It's all checked on your device, which matters because the things people need to identify are often tokens and keys.
Checked on your device. Nothing is sent anywhere or put in the URL.
What it recognizes
Each check is a simple, predictable rule, so you can tell why it made its suggestion. Where a tool already has a parser, the rule uses it, so a match means that tool can open the value. When more than one rule matches, the likeliest comes first and you choose.
| Format | Recognized by | Opens in |
|---|---|---|
| JWT | Three dot-separated Base64URL parts whose first two decode to JSON objects Opens in JWT Decoder | JWT Decoder |
| JSON | Parses as a JSON object or array Opens in JSON Formatter & Validator | JSON Formatter & Validator |
| X.509 certificate | A -----BEGIN CERTIFICATE----- block, or Base64 DER, that decodes as a certificate Opens in X.509 Certificate Decoder | X.509 Certificate Decoder |
| Base64 / Base64URL | Only Base64 characters, a valid length, and decodes to readable text or a known file type Opens in Base64 Encoder & Decoder | Base64 Encoder & Decoder |
| URL or query string | Parses as a URL with a scheme (https://…), or looks like key=value&key=value Opens in URL Encoder & Query Parser | URL Encoder & Query Parser |
| Percent-encoding | Contains %XX escapes that decode cleanly (a whole URL goes to the URL parser instead) Opens in URL Encoder & Query Parser | URL Encoder & Query Parser |
| HTML entities | Contains character references like & or — Opens in HTML Entity Encoder & Decoder | HTML Entity Encoder & Decoder |
| Cron schedule | Five fields that parse as a valid cron expression, or a macro like @daily Opens in Cron Expression Explainer | Cron Expression Explainer |
| Unix timestamp | A 10-digit (seconds) or 13-digit (milliseconds) number: 2001 to 2286 Opens in Timestamp Converter | Timestamp Converter |
| ISO 8601 date | A date like 2026-09-24 or 2026-09-24T18:30:00Z Opens in Timestamp Converter | Timestamp Converter |
| UUID | 8-4-4-4-12 hex digits; the version is read from the 13th digit Opens in UUID & Hash Generator | UUID & Hash Generator |
| Hash | 40, 64, 96 or 128 hex digits: the lengths of SHA-1, SHA-256, SHA-384 and SHA-512 Opens in UUID & Hash Generator | UUID & Hash Generator |
| Unix permissions | Three or four octal digits, or rwxr-xr-x as ls -l prints it Opens in chmod Calculator | chmod Calculator |
Why guesses can be ambiguous
Some strings genuinely fit more than one format. https://example.com/?a=1&b=2 is a URL, but the & in it means it was copied out of HTML source,
so it's HTML-escaped as well. The identifier shows every match it finds, most specific first, rather
than silently picking one.
Short strings are where coincidences happen. SGk= is valid Base64 for
"Hi", but it could just as well be an ID someone chose. That's why short Base64 only counts when
it decodes to plain text, and why it never opens anything on its own: you always choose.
What it never guesses: encrypted data
Encoding and encryption look alike on screen but are opposites. Base64, percent-encoding and HTML entities are reversible by anyone, which is how this page can recognize them. Good encryption is designed to be indistinguishable from random bytes, so there is no honest rule for spotting it, and an identifier that claims to "detect AES" is guessing.
So when a string is valid Base64 but decodes to neither text nor a known file type (PNG, JPEG, GIF, PDF, gzip or ZIP), the identifier says it doesn't recognize it. It might be encrypted, compressed, a random key or just noise, and nothing in the bytes says which. The encoding vs encryption glossary entry explains the difference in more depth.
FAQ
Where does my text go when I open a tool?
Nowhere outside your browser. Clicking a suggestion puts the text in this tab's session storage, the tool page reads it once as it loads and deletes it straight away. It is never put in the URL, because URLs end up in browser history and server logs. If the tool page doesn't load within a minute, the text is ignored.
Why doesn't it just open the right tool?
Because a wrong guess that navigates away is worse than no guess. Even when there's exactly one match, you see what it matched and why, and you decide whether to open it.
My value isn't recognized. Is something wrong with it?
Not necessarily. The rules are deliberately narrow: an MD5 hash (32 hex digits) isn't one of the SHA lengths, a six-field Quartz or Spring cron expression isn't standard five-field cron, and a 9-digit timestamp from before 2001 is left alone because short numbers are too often something else. Open the tool you expected directly: its own error message will say exactly what it objects to.
Why can't it open UUIDs and hashes?
It can tell you what they are, but there's nothing to decode: a UUID is an identifier and a hash is a one-way fingerprint. The UUID & Hash Generator link is there so you can make a fresh one or hash some text to compare against.
Related tools
- JWT Decoder — Read a token’s header and payload, and see when it expires.
- Base64 Encoder & Decoder — Encode and decode Base64 and Base64URL, text or files.
- URL Encoder & Query Parser — Percent-encode text and break any URL into its parts.
- Timestamp Converter — Unix timestamps to readable dates and back, in UTC and your local time.