URL Encoder / Decoder
Encode text for a URL component or decode percent-encoded text. The tool does not claim that encoding an entire URL and encoding one query value are interchangeable.
Browser-localFreeNo upload required
What this tool is for
Encode text for a URL component or decode percent-encoded text. The tool does not claim that encoding an entire URL and encoding one query value are interchangeable.
How to use
- Choose Encode when preparing a path or query component, or Decode when inspecting encoded text.
- Paste only the component you intend to transform unless you have reviewed the full
URLbehavior. - Inspect reserved characters such as `/`, `?`, `&`, `=`, and `#` before copying the result.
Example
Encode `summer sale & clearance` for one query value, then decode it to confirm the original spaces and ampersand return.
FAQ
Should I encode a complete URL?
Usually encode individual components. Encoding the complete URL can also encode structural separators.
Why does a plus sign remain different from `%20`?
This tool uses URL component encoding; HTML form encoding has additional plus-for-space conventions.
Reproducible examples
Known inputs and expected results
Run these examples in the workspace above and compare the result with the documented output.
Encode a query value
- Input
- summer sale & clearance
- Options
- Choose component Encode.
- Action
- Encode the value before assigning it to one query parameter.
- Expected output
- summer%20sale%20%26%20clearance
- Explanation
- The ampersand is encoded as data instead of becoming another query separator.
Unicode round trip
- Input
- 你好
- Options
- Encode, then decode the generated component.
- Action
- Run both directions.
- Expected output
- %E4%BD%A0%E5%A5%BD, which decodes back to 你好.
- Explanation
- encodeURIComponent operates on the UTF-8 representation of the Unicode text.
Error or unsupported case
Incomplete percent escape
- Input
- %E4%BD%A0%E5
- Expected error or limit
- decodeURIComponent reports a malformed URI sequence.
- Safer alternative
- Recover the complete encoded bytes or use the source text; do not guess missing escapes.
When not to use this tool
- Encoding an entire
URLas if it were one component - application/x-www-form-urlencoded plus-to-space semantics
Algorithm and assumptions
The implementation follows encodeURIComponent/decodeURIComponent semantics, keeps URL structure separate from component data, and does not translate plus signs to spaces.
Input and output
Input is plain or percent-encoded text. Output is transformed with JavaScript URL component rules.
Supported formats and behavior
- UTF-8 percent encoding
- Reserved-character inspection
- Readable errors for malformed percent sequences
Limits
- Not a
URLvalidator - Does not submit or fetch the resulting
URL
Edge cases and common errors
- A literal percent sign must be encoded
- Malformed `%` sequences cannot be decoded
- Unicode becomes one or more UTF-8 byte escapes
Release testing
Release checks cover spaces, ampersands, slashes, Unicode, literal percent signs, malformed sequences, round trips, copy, and clear.
Privacy boundary
The input and result stay in this browser session. ZZP Box does not upload or store the values entered in this tool.
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