URL Encoder & Decoder

What is URL Encode/Decode?

URL encoding (also called percent-encoding, RFC 3986) replaces bytes that have special meaning in URLs — like space, `&`, `=`, `?`, `#`, `/` — with `%XX` hex sequences. It's what makes it possible to put arbitrary text into query strings, path segments, and fragments without breaking the URL grammar.

How to URL encode or decode

1. 1Choose Encode or Decode at the top.
2. 2Paste your text or encoded URL into the input.
3. 3The output updates live in the right panel.
4. 4Optionally toggle 'encode reserved characters' if you're encoding a full URL vs a single component.

Use Cases

Code Examples

// For a full URL: leaves : / ? # alone
encodeURI("https://a.com/path?q=x y");
// For a single component: escapes everything
encodeURIComponent("hello world & friends");

from urllib.parse import quote, quote_plus
quote("hello world")        # -> "hello%20world"
quote_plus("hello world")   # -> "hello+world"  (query string style)

import "net/url"

url.QueryEscape("hello world")   // "hello+world"
url.PathEscape("hello world")    // "hello%20world"

jq -Rr @uri <<< "hello world"      # "hello%20world"

Key Concepts

Reserved characters

The characters `: / ? # [ ] @ ! $ & ' ( ) * + , ; =` have special meaning. Encode them when they appear inside a value; leave them when they're structural.

encodeURI vs encodeURIComponent

`encodeURI` is for a whole URL — it preserves reserved characters. `encodeURIComponent` is for one field's value — it escapes everything except unreserved characters.

Space: %20 vs +

In paths, space is `%20`. In query strings, `+` is also accepted (from HTML form encoding, `application/x-www-form-urlencoded`). Servers accept both.

Double encoding

Encoding an already-encoded string produces `%2520` (which decodes to `%20`, not space). Almost always a bug. Decode once and check.

Tips & Best Practices

• ▸In code, always use the library — never hand-roll `str.replace(' ', '%20')`. There are dozens of characters to handle.
• ▸Use `encodeURIComponent` for query values and path segments. Use `encodeURI` only when encoding a full URL you assembled yourself.
• ▸If a URL has `%2520` in it, someone encoded twice. Common in ad-tracking and OAuth `state` params.
• ▸Fragments (`#...`) are never sent to the server — they're client-only. Don't rely on them for server-side routing.