Free URL Encode / Decode Tool

How this tool computes its result

Encodes text by passing it through encodeURIComponent(), which converts special characters (including spaces, punctuation, and non-ASCII) to percent-encoded form (e.g., space → %20, & → %26). Decoding attempts the reverse via decodeURIComponent() inside a try-catch; if the string is malformed (e.g., an incomplete percent sequence like "%2"), decodeURIComponent() throws and the tool silently returns an empty string with an error message displayed. The UI provides convenience buttons to swap the input between encoded and decoded forms, and a clear button to reset.

Worked example

Entering plain text "hello world & friends" produces encoded output "hello%20world%20%26%20friends". Clicking "Use Encoded as Input" swaps the fields, then encoding that already-encoded string produces "hello%2520world%2520%2526%2520friends" (double-encoding the percent signs). Entering an incomplete percent sequence like "hello%2" into the input and attempting to decode shows an error message "Input is not valid URL-encoded text for full decode." because decodeURIComponent() throws.

When not to use this tool

encodeURIComponent() reserves certain characters (~-_.!) and does not encode them, which is correct for URL components but incorrect for HTML entities or other contexts. Also, this tool does not handle different URL contexts (e.g., the query string component, the path component, or the full URL) — all use the same function, so a colon in a URL path and a colon in a domain both become %3A.

Common mistakes

• - Pasting a fully encoded URL as input and expecting a single decode to return the original text — if the original included a literal percent sign followed by characters, that percent is encoded as %25, so it requires two levels of decoding.
• - Assuming all special characters are encoded — the reserved characters ~-_.! are intentionally left unencoded by encodeURIComponent(), so "hello~world" stays as "hello~world" rather than becoming "hello%7Eworld".
• - Entering non-ASCII characters and expecting consistent results across browsers — the tool uses the browser's TextEncoder/TextDecoder for UTF-8 encoding, but some older browsers or restricted contexts may not support non-ASCII percent-encoding.

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