URL Encoder / Decoder

URL encoding (also known as Percent-Encoding) is a mechanism used to translate special characters within a Uniform Resource Identifier (URI) under specific conditions. Internet routers and web browsers are designed to interpret a specific set of characters (like `/`, `?`, `&`, `=`, `#`) as syntax controls. If your target data contains these characters (for example, putting an email address or another URL inside a query parameter), you must encode them to prevent parsing errors.

Percent-encoding replaces non-ASCII or reserved characters with a percent sign (`%`) followed by a two-digit hexadecimal representation of the character's ASCII byte value. For example, a space character is replaced by `%20`, a question mark becomes `%3F`, an ampersand becomes `%26`, and an equals sign becomes `%3D`.

Under URI guidelines (RFC 3986), characters are split into two groups: Unreserved characters (letters `A-Z`, `a-z`, numbers `0-9`, and symbols `-`, `_`, `.`, `~`) do not have special syntactic meaning and never need encoding. Reserved characters (such as `/`, `?`, `:`, `@`, `&`, `=`, `+`, `$`) have syntactic purposes. If they are used as part of the data query, they must be escaped.

No. URL encoding actually increases the character length of your text blocks. Since a single space (1 character) translates into `%20` (3 characters), your query string grows longer. Keep this in mind when developing API layouts with tight URL length limits (typically 2048 characters in older web browsers).

In JavaScript, `encodeURI` is designed to encode a full website address, leaving address controls (like `http://`, slashes, and port colons) intact. `encodeURIComponent` is designed to encode a single query key or value parameter, escaping all reserved characters (including slashes and colons) to ensure they do not break the parent URL structure.

Yes, but you will need to run the decoding process twice. If a string is encoded twice, symbols like `%` become `%25`. Running the decoder once will return a percent-escaped string (e.g. `%20`), and running it a second time will restore the original standard text.

No. Our URL Encoder / Decoder runs 100% locally in your web browser. The conversions are processed using standard client-side JavaScript APIs (like `encodeURIComponent` and `decodeURIComponent`). Your confidential passwords, API keys, and email addresses are never sent over the internet, ensuring total data security.

You need URL encoding whenever you place user-supplied data inside a URL query parameter. Common examples include: embedding an email address in a subscribe link (`?email=user%40example.com`), passing a full URL as a redirect parameter (`?return_url=https%3A%2F%2Fexample.com%2Fdashboard`), building search query strings (`?q=image+compressor+free`), and constructing UTM tracking links where the campaign name contains special characters.

Both represent a space, but in different contexts. The `+` character is used in the `application/x-www-form-urlencoded` format — which is what HTML form submissions use by default. The `%20` encoding is the strict RFC 3986 percent-encoding standard for spaces in URI components. When building URL query parameters manually (as in API integrations and UTM links), always use `%20` to be safe. Our encoder uses `encodeURIComponent`, which produces `%20` — the most universally compatible encoding.

If a string has been encoded more than once, you need to run the decoder multiple times. For example, a double-encoded space looks like `%2520` (the `%` sign itself was encoded to `%25`). Running the decoder once gives `%20`, and running it again gives the original space. If you paste a URL into the decoder and it still contains `%` sequences after decoding, run the decoder again until the output stabilises.