URL Encoder & Decoder (Percent-Encoding)
Percent-encode or decode URLs and query strings in any language with encodeURIComponent, encodeURI or form encoding (+). Broken % sequences show the exact error position.
- Runs in your browser (no upload)
Percent-encodes everything as UTF-8 except letters, digits and - _ . ! ~ * ' ( ).
Result
Input length
37
Result length
95
How to use
- Choose Encode or Decode and the method (encodeURIComponent, encodeURI or form encoding).
- Type text or a URL; the result appears immediately.
- Copy the result, or use "Use the result as input and reverse" to check the round trip.
FAQ
What is the difference between encodeURIComponent and encodeURI?
encodeURIComponent also encodes / ? & = and similar characters, so use it for query values and path segments. encodeURI keeps URL delimiters, so use it for a whole URL.
What happens with a broken % sequence?
The browser's decodeURIComponent just throws an error; this tool shows the position (line and column) and the problem, including UTF-8 byte sequences that are cut off.
Is a space encoded as %20 or +?
As %20 with encodeURIComponent and encodeURI, and as + with form encoding (application/x-www-form-urlencoded).
Notes & limitations
- What you enter is processed only on this page and is not sent to YUCTS servers.
- Input is limited to 2,000,000 characters.
- Only UTF-8 is supported; URLs encoded in other character sets (such as Shift_JIS) are not read correctly.
- It does not check whether a URL is otherwise valid (for example the domain name).
Data sources
- RFC 3986: Uniform Resource Identifier (URI): Generic Syntax(opens in a new tab) — Checked on: 2026-10-31
- WHATWG URL Standard: application/x-www-form-urlencoded(opens in a new tab) — Checked on: 2026-10-31
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