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UUID Validator / Decoder

Validate UUIDs and decode their version, variant, and the timestamp and MAC a v1 carries.

Related tools

All Encoding & decoding tools →
HTML Entity Encoder / DecoderConvert text to HTML entities and back, escaping <, >, &, quotes and optionally all non-ASCII characters.Base64 Encoder / DecoderEncode and decode Base64 online — free.JWT decoderDecode a JWT, read its claims and dates, and check its HMAC signature.URL encoder / decoderEncode and decode URLs and query parameters.XML Formatter / ValidatorPretty-print, minify and check whether XML is well-formed, all in your browser.YAML Formatter / ValidatorTidy YAML — normalize indentation, convert tabs to spaces and flag tab-indent errors.UUID generatorGenerate UUID v7, v4, v5, v3, v1 or v6 in bulk, in several output formats.JSON String Escape / UnescapeTurn raw text into a JSON-safe string and back, with control characters, \uXXXX, emoji surrogate pairs and lone surrogates handled exactly like JSON.stringify.

UUID Validator / Decoder is free to use as often as you like, directly from this page. It sits under Encoding & decoding in our catalogue, alongside HTML Entity Encoder / Decoder and Base64 Encoder / Decoder.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does UUID Validator / Decoder do?

Validate UUIDs and decode their version, variant, and the timestamp and MAC a v1 carries.

When would I actually use this?

Reading a payload someone sent you, embedding a small file in a config, and finding out why a query string breaks once it reaches the server.

What is the most common mistake?

Treating Base64 as a form of protection. It is an encoding, not encryption — anyone can decode it instantly, and a token pasted into a public issue is a leaked token.

How is UUID Validator / Decoder different from HTML Entity Encoder / Decoder?

They sit next to each other but answer different questions: HTML Entity Encoder / Decoder is the one to open when you need it to convert text to HTML entities and back, escaping <, >, &, quotes and optionally all non-ASCII characters. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Base64 Encoder / Decoder is the closest one after this: Encode and decode Base64 online — free.

What else is worth having open alongside it?

JWT decoder and URL encoder / decoder — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

The encodings follow their RFCs, so a round trip is lossless. URL encoding has two variants — one that encodes a space as %20 and one as a plus sign — and the tool says which it applies.

Further reading

All guides →
GuideURL Encoding Explained: Percent-Encoding and Where It BitesPercent-encoding is decided per URL component, which is the whole source of the confusion. A slash is legal in a path and must be escaped in a query value; a space is %20 in a path and may be + in a form body. Here are the exact RFC 3986 sets, the three JavaScript functions that disagree, and the traps.ExplainerWhat Is Base64 Encoding?Base64 turns binary data into safe text. Here's what it does, why it exists, why it isn't encryption, and the size cost it adds.ExplainerWhat Is a JWT (JSON Web Token)?A JWT is a compact, signed token used to carry identity between services. Here's its three parts, how it's used for auth, and its security limits.ExplainerWhat Is a UUID (and When to Use It)?A UUID is a 128-bit identifier that's unique without any central authority. Here's what it looks like, why it's useful, the versions, and when to use one.GuideBuilding a URL With Parameters That Survives a Copy-PasteThree encodings, one visible difference: %20 or +. The builder's form mode matches URLSearchParams byte for byte on seventeen values — but give it a base URL with a fragment and every parameter lands inside the hash, where no server sees it.ExplainerWhat Is Inside a JWT — and What It Does Not ProtectA JWT is signed, not encrypted. Anyone holding the token can decode the payload and read every claim in it. Here is a real token, decoded without any key, plus the three attacks the signature is supposed to stop and the one problem it cannot solve.