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URL Encoder / Decoder

Developer Tools

encodeURI and decodeURI online

Quick Answer

URL Encoder / Decoder: encodeURI and decodeURI online. URL Encoder / Decoder uses standard developer formulas to compute accurate results instantly.

Direction:Mode:

Input

Output

component vs full

  1. 1encodeURIComponent escapes ALL reserved chars (: / ? & =) — use it for query parameter VALUES.
  2. 2encodeURI keeps structure chars intact — use it on a complete URL.
  3. 3Example: ? q=a&b → value "a&b" must encode & to %26, or it becomes a second parameter.
  4. 4Space: %20 in component mode; form submissions (application/x-www-form-urlencoded) use + instead.

RFC 3986 character classes

: / ? # [ ] @Reserved (URL structure delimiters)
! $ & ' ( ) * + , ; =Sub-delimiters
A-Z a-z 0-9 - _ . ~Unreserved (never encoded)
UTF-8 noteChinese char = 3 bytes = %XX%XX%XX

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How to Use

  1. Paste or type content: drop code/text into the URL Encoder / Decoder or fill the parameters.
  2. Choose mode/options: switch format, rules or processing as needed.
  3. Live output: results appear instantly — nothing is submitted, data stays in your browser.
  4. One-click copy: copy the output straight into your development environment.

Key Points

  • URL Encoder / Decoder is a free online developer tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: encodeURI and decodeURI online.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

URL Encoder / Decoder formula

URL Encoder / Decoder uses standard developer formulas to compute accurate results instantly.

FAQ

How do I use the URL Encoder / Decoder?
Open the page and fill in the input fields — results update automatically. encodeURI and decodeURI online.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on RFC 4648, ECMA-262 and related specifications. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. URL Encoder / Decoder[EB/OL]. https://www.yijiansuan.com/en/c/dev/url-codec

Results provided by this tool are for reference only and do not constitute professional advice.