What does %20 mean in a URL?

It is the percent-encoded representation of a space character, used because a literal space can break how a URL is parsed.

Why do some URLs use a plus sign instead of %20 for spaces?

The plus sign is a legacy convention from HTML form submission specifically within query strings. %20 is the more universally correct encoding for spaces outside of query strings.

Which characters need to be URL encoded?

Reserved characters with structural meaning in a URL, such as &, =, ?, #, and /, along with spaces and non-ASCII characters, need encoding when they appear as literal data rather than structural parts of the URL.

URL Encoder / Decoder

Percent-encode URLs and URI components, or decode encoded strings back to plain text.

Encode component (escapes all special chars) Encode full URL (preserves ://?=&#)

Input

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Encoded Output

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Encoded Input

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Decoded Output

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Common Percent-Encoded Characters

Space %20 (or +)

/ %2F

@ %40

? %3F

= %3D

& %26

# %23

+ %2B

: %3A

% %25

[ %5B

] %5D

How to Use

Encode Component — encodes all special characters including / ? = & #. Use this for query parameter values.
Encode Full URL — preserves :// ? = & # so the URL structure stays intact. Use this for encoding a complete URL.
Decode — paste any percent-encoded string to convert it back to plain text. Both %XX and + (space) forms are supported.
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About this URL Encoder/Decoder

URLs can only safely contain a limited set of characters. URL encoding (also called percent-encoding) converts anything outside that set — spaces, symbols, non-English letters — into a percent sign followed by a two-digit hex code, so the URL remains valid and unambiguous.

Why spaces become %20 or +

A literal space in a URL can break parsing, since spaces normally separate distinct pieces of a request. %20 is the standard percent-encoded form of a space. In query strings specifically, a + is also commonly accepted as a space, a legacy convention from HTML form submission — but %20 is the more universally correct encoding outside of query strings.

Reserved characters that need encoding

Characters like &, =, ?, #, and / have special meaning in a URL's structure (separating parameters, marking a fragment, and so on). If one of these characters needs to appear as literal data inside a parameter value — for example, an email address containing "&" or a search term containing "#" — it must be encoded so it isn't misread as part of the URL's structure.

Where this matters in practice

Building a link that passes a search term, email address, or freeform text as a query parameter
Decoding a tracking or redirect URL to see its actual destination and parameters
Debugging an API request where special characters in a parameter are breaking the request