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URL Encoder, Decoder & Query String Parser

Percent-encode or decode text for use in URLs, and take any URL apart into its host, path and query parameters. URLs often carry tokens, emails and internal hostnames, so it all runs locally in your browser and nothing is uploaded.

Encode or decode

Mode

Encode Decode

Encoding style

Component — for one value; encodes / ? & = # Full URL — keeps the URL's own / ? & = # Form — spaces become +

Input

Output

Parse a URL or query string

URL, relative path, or query string

What percent-encoding is

URLs may only contain a small set of characters. Anything else, and anything that would otherwise be read as URL syntax, is written as a percent sign followed by the byte's two hexadecimal digits: a space is %20, a slash inside a value is %2F, and a non-ASCII character becomes the percent-encoded bytes of its UTF-8 form — é is %C3%A9.

The characters that never need encoding are letters, digits and - . _ ~. The rest depends on where in the URL the text is going, which is why there are three styles here.

Which encoding style to use

Component (encodeURIComponent) for a single value you are placing inside a URL, such as a query parameter or a path segment. It encodes / ? & = # so the value cannot break out of its slot. This is the right choice most of the time.
Full URL (encodeURI) for an entire URL that just has a space or an accented character in it. It leaves / ? & = # alone, so the URL keeps its structure. Applying it to a single value is a common bug: an ampersand in the value survives and splits the parameter.
Form (application/x-www-form-urlencoded) is what HTML forms and URLSearchParams produce: the same as component encoding, except a space becomes +.

In code

// JavaScript
encodeURIComponent('a b/c&d')          // 'a%20b%2Fc%26d'
const url = new URL('https://example.com/search')
url.searchParams.set('q', 'a b&c')     // url.search === '?q=a+b%26c'

# Python
from urllib.parse import quote, quote_plus, urlencode
quote('a b/c', safe='')                # 'a%20b%2Fc'
quote_plus('a b')                      # 'a+b'
urlencode({'q': 'a b&c'})              # 'q=a+b%26c'

# curl
curl --get --data-urlencode 'q=a b&c' https://example.com/search

Prefer URL and URLSearchParams (or your language's equivalent) over building URLs by string concatenation. They encode each part correctly, so you don't have to decide by hand.

FAQ

Should a space be %20 or +?

%20 is valid everywhere. A + means "space" only in form-encoded data, which in practice means query strings. In a path, a plus sign is just a plus sign, so /c++/notes really does contain two plus characters. When in doubt, use %20.

Why do I see %2520 in my URL?

That's double encoding. %20 was encoded a second time, turning its percent sign into %25. It usually means a value was encoded once by your code and again by a library or framework. Decoding here flags this when the result still contains percent sequences.

Why does decoding fail with "not valid UTF-8"?

Percent-encoded bytes are only text if they form valid UTF-8. Older systems sometimes encode in Latin-1, where é is a lone %E9, which is not valid UTF-8 on its own. The tool reports this rather than showing replacement characters.

Is anything after the # sent to the server?

No. The fragment stays in the browser. That's why the parser shows it separately, and why a ? inside a fragment is not part of the query.

How are repeated keys and arrays handled?

There is no single standard. The parser keeps every occurrence in order and marks repeated keys, so tag=a&tag=b shows both. Conventions such as a[]=1&a[]=2 are shown literally, since how they're interpreted depends on the server framework.

HTML Entity Encoder & Decoder — Escape text for HTML, or decode entities exactly as a browser does.
Format Identifier — Paste anything to find out what it is (a JWT, JSON, a certificate, Base64, a cron schedule and more), then open it in the right tool.