Input
Output
⚠️ Malformed percent-encoded sequence detected.
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Whenever a web browser submits a search query, communicates with a REST API, or navigates to a hyperlinked address, it transmits a Uniform Resource Identifier (URI). Under the official internet standard RFC 3986, URLs are restricted to a narrow set of characters from the standard US-ASCII repertoire.
Characters that fall outside this permissible set—such as whitespace, quotation marks, punctuation, non-English scripts, and emojis—must be converted into a universally recognized format called URL encoding or percent-encoding.
%) followed by its two-digit hexadecimal byte value in US-ASCII / UTF-8. For instance, a space character (ASCII 32, hex 20) becomes %20.
A common source of bugs in frontend JavaScript and API integration is confusing encodeURI() with encodeURIComponent(). Understanding their distinct purposes is essential:
: / ? # [ ] @ ! $ & ' ( ) * + , ; =. This ensures that the structural components of the URL (e.g. https://example.com/path?key=value) remain intact and clickable./ ? : & = # + $ , ;. For example, if a query parameter contains an ampersand (such as tag=seo&marketing), failing to component-encode it causes servers to split it into two separate parameters. Component-encoding turns & into %26, preserving your parameter as a single atomic value.| Character | Standard Meaning in URLs | Handled by encodeURI() | Handled by encodeURIComponent() |
|---|---|---|---|
| Space ( ) | Illegal in URLs | %20 |
%20 (or + in forms) |
| Forward Slash (/) | Path directory separator | Preserved as / |
Encoded as %2F |
| Question Mark (?) | Query string delimiter | Preserved as ? |
Encoded as %3F |
| Ampersand (&) | Query parameter separator | Preserved as & |
Encoded as %26 |
| Equals Sign (=) | Key-value assignment | Preserved as = |
Encoded as %3D |
| Colon (:) | Protocol / port separator | Preserved as : |
Encoded as %3A |
| Hash (#) | Fragment / anchor identifier | Preserved as # |
Encoded as %23 |
| At Sign (@) | User info delimiter | Preserved as @ |
Encoded as %40 |
Decoding reverses the percent-encoding transformation, restoring hexadecimal sequences back to human-readable UTF-8 strings. Our tool detects percent signs followed by two valid hex digits and reconstructs original characters.
If a sequence is damaged or truncated (for instance, an isolated percent sign like % without two hex numbers, or an invalid hex pair like %GG), the tool triggers an informative warning and safeguards your text rather than crashing the page.
2026-10-12T10:00:00Z), emails, and multi-word terms safely over GET requests.