URL Encoder & Decoder (Percent-Encoding Utility)
Encode or decode URLs using percent-encoding client-side.
URL Encoder & Decoder
Encode text into percent-encoded URI strings or decode encoded URLs back to human-readable format.
How It Works & Calculation Method
Uniform Resource Identifiers (URIs) only permit a restricted character set from the standard US-ASCII spectrum. Characters outside this range—such as spaces, ampersands, slashes, and foreign letters—must be percent-encoded.
Our client-side tool uses standard `encodeURIComponent` and `decodeURIComponent` routines to ensure web URLs, tracking query parameters, and OAuth redirect callbacks transmit without corruption.
Encoding converts reserved and non-ASCII characters into their UTF-8 byte sequences, formatted as a '%' symbol followed by two hexadecimal digits.
Decoding scans for '%' triplets and reconstructs the original UTF-8 characters.
Mathematical Formula
Percent-Encoding: Character -> UTF-8 byte -> %HH (e.g. Space -> %20, '&' -> %26)Worked Example: Encoding Query Parameters
A developer encodes a search query containing spaces and special symbols: 'smartphones & gadgets?'.
Common Pitfalls to Avoid
- •Using encodeURI instead of encodeURIComponent when encoding individual query string parameters.
- •Double-encoding URLs that were already percent-encoded (e.g. %20 becoming %2520).
- •Forgetting that characters like '&', '=', and '?' carry special semantic meaning in URL query strings.
Who This Tool Is For
- •Web developers assembling REST API query strings and webhook callback parameters.
- •SEO specialists auditing UTM campaign tracking tags in marketing URLs.
- •Systems engineers debugging OAuth redirection endpoints.
How to Use the URL Encoder/Decoder
Paste URL or String
Enter the text or URL you wish to transform.
Select Action
Click Encode to percent-encode, or Decode to convert back.
Copy Result
Copy the transformed URL string directly to your clipboard.