Free online URL encoder and decoder. Encode special characters with percent-encoding (%20) for safe URLs and query strings, or decode encoded URLs back to readable text. Supports encodeURI, encodeURIComponent, and '+' for spaces modes.
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Paste the text you want to encode and choose an encoding mode:
Decoding is the reverse operation:
Percent-encoding (also called URL encoding) is the mechanism for representing arbitrary data in a URL. Reserved characters — : / ? # [ ] @ ! $ & ' ( ) * + , ; = — plus spaces and non-ASCII letters — are replaced by a '%' followed by the two hex digits of their UTF-8 byte. For example, a space becomes %20, 'đ' becomes %C4%91, and '?' becomes %3F. This guarantees the URL is unambiguous: encoded characters can never be misinterpreted as URL syntax. The name comes from ASCII code 37 (%), which is used as the escape marker.
JavaScript offers two encoding functions with different purposes. encodeURIComponent encodes every character except A-Z a-z 0-9 - _ . ! ~ * ' ( ). It is the correct choice for building query string values, since it escapes characters that have syntactic meaning in a URL such as & = ? and #. encodeURI leaves the reserved set ; / ? : @ & = + $ , # untouched, which is exactly what you want when encoding a complete URL whose structure you want to preserve. A common bug is using encodeURI for a parameter value containing '&' or '#', or using encodeURIComponent on a full URL — both corrupt the result.
In the application/x-www-form-urlencoded format (used by HTML forms and many APIs), a space is encoded as '+', not '%20'. Percent-encoding of the same query string normally produces %20. When decoding, a robust tool therefore converts '+' back to a space first. This asymmetry trips up developers: a value that literally contains a '+' must be percent-encoded as %2B to survive the trip through a form, otherwise it arrives as a space. This tool lets you toggle the '+' behavior on encode and always normalizes '+' when decoding in Component mode.
URL encoding (percent-encoding) transforms characters so they are safe inside a URL: spaces become %20, and reserved characters like ? and & become %3F and %26. HTML encoding transforms characters so they render safely in HTML documents: < becomes <, > becomes >, & becomes &. They use different escape schemes and are not interchangeable — encoding a URL with HTML entities produces a broken link, and vice versa.
In most cases you should encode only the dynamic parts: the parameter names, values, and any dynamic path segments, using encodeURIComponent. The URL structure (https://, the domain, slashes, ? and = separators) should stay as-is. If you run encodeURIComponent over a full URL, you get https%3A%2F%2Fexample.com — which browsers will not navigate to as a normal link, because the scheme and slashes have been escaped.
Yes. Modern URLs are encoded as UTF-8 bytes, so Vietnamese diacritics like ế, ơ, ư and characters like đ are converted to their UTF-8 percent-encoded form (e.g. 'đ' becomes %C4%91). The encoded string is pure ASCII and safe to embed in any URL or query string. The server then decodes it back to the original text. This also works for emoji and any other Unicode characters.
Decoding fails when the input is not valid percent-encoding — for example, a '%' not followed by two hex digits (%G1), or an incomplete sequence at the end of the string. It can also fail if the string contains a '%' that was written by a different encoding scheme. Normal text that was never encoded does not need decoding: run Encode on plain text, and only Decode strings you know were percent-encoded.
No. All encoding and decoding happens locally in your browser using built-in JavaScript functions (encodeURI, encodeURIComponent, decodeURI, decodeURIComponent). Nothing you type is transmitted over the network — you can even use this tool offline once the page is loaded.