UTF-8 decoder and validator
Paste bytes to check they are well-formed UTF-8 and read the text, useful when diagnosing garbled Arabic.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter utf-8 bytes (hex).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Bytes are checked against Unicode Table 3-7 of well-formed sequences: C0, C1 and F5 to FF, overlong forms, surrogates and values above U+10FFFF are rejected.
Example
Result: Decoded text: €; Characters: 1; Bytes: 3.
Limits and caveats
- It stops at the first error rather than substituting �, so you can see where the problem is.
- The table lists the first 400 characters only.
Questions about this tool
Why does Arabic show up as symbols like ال?
UTF-8 bytes were read as Windows-1252. Paste the bytes here to confirm they are valid UTF-8.
What is an overlong encoding?
A character written with more bytes than needed, such as C0 AF instead of 2F. The standard forbids it for security reasons.
Does it accept %D8%B3 style input?
Yes. %, 0x and \x markers are removed and the values are read as bytes.