URL Encoder / Decoder

Written byOleh Soloninupdated 25 September 2026

Mode

Scope

Text

Result

Resulthttps%3A%2F%2Fexample.com%2Fsearch%3Fq%3Dhello%20world
Result length54

Two modes, because a full URL and a parameter need different treatment

Encode query parameters and paths, or decode a URL full of %20s. Choose between encoding a component or a whole URI.

URLs only tolerate a limited character set. Everything else — spaces, ampersands, Cyrillic, emoji — has to be percent-encoded, which is why links turn into strings of %D0%BF.

The distinction that matters: encoding a full URI preserves the structural characters like : and /, while encoding a component escapes them. Getting this backwards is why a query parameter containing a URL so often breaks.

How to use

Paste the string: a single parameter value, a whole address, or something already encoded.
Pick the direction — encode or decode.
The scope is the decision that matters: a component is encoded in full, while a whole URI keeps its structure intact.

A component or a whole address

This is the most repeated mistake when building links. Inside a parameter value, &, = and / are content and must be encoded. In a whole address the same characters carry the structure, and encoding them destroys the link — an encoded slash turns a path into one long segment.

The default example shows the gap at a glance: encoded as a component the address runs to 54 characters and stops being an address; encoded as a URI it is 42 characters and still works.

Both rows come from the calculator on this page. The first scope is the right one when an address itself becomes a parameter value — a return URL after sign-in, for example.
Scope	What happens to https://example.com/search?q=hello world	Characters
Component	everything is encoded, including : / ? and =	54
Whole URI	the structure survives; only the space is encoded	42

One percent group per byte

Percent-encoding represents bytes, not characters. An ASCII letter is one byte in UTF-8 and any other code point two to four; an accented letter or an emoji can be several code points; each byte gets its own %XX group.

That is where long links come from. The rule also explains the one character people forget: a percent sign meant literally has to be written %25, or the decoder looks for two hex digits after it and gives up.

Every value comes from the calculator on this page. Note the plus: in a parameter value it must become %2B, because form data reads a bare plus as a space — the classic breakage for email addresses with a plus alias and phone numbers with a country code.
Character	Encodes to	Bytes in UTF-8
space	%20	1
+	%2B	1
%	%25	1
/	%2F — as a component only	1
&	%26 — as a component only	1
é	%C3%A9	2
🥨	%F0%9F%A5%A8	4

What this calculator shows

The encoded or decoded string, with length
Component mode for query values and path segments
Full-URI mode that leaves the structure of a link intact

What to keep in mind

Component mode escapes reserved characters such as & = ? / :
Malformed percent sequences are reported rather than silently repaired.

FAQs

Which mode should I use?

Component when you are encoding one value: a search term, a file name, a return address. Whole URI when you already hold a finished link and only need to tidy up spaces and non-Latin characters.

Why is a space sometimes %20 and sometimes +?

%20 is valid anywhere in a URL. The plus belongs to form data sent as application/x-www-form-urlencoded, where + means a space and a real plus has to be written %2B.

Do non-Latin URLs actually work?

Yes. The browser encodes them on the way out and shows them readable in the address bar. The trouble starts elsewhere: in an email, in a chat message and in a server log the same link is a wall of percent groups.

Why does one accented letter produce two groups?

Because bytes are what gets encoded. In UTF-8 é is two bytes, C3 and A9, and each takes its own group: %C3%A9. An emoji, at four bytes, produces four groups.

Can I encode the same string twice?

You can, and it will bite you. The percent sign encodes itself as %25, so %20 becomes %2520. The other side decodes once and sees %20 instead of a space. Double decoding is the same fault in reverse: it can recover characters that were never there.

What does an incomplete percent group mean?

That a % is not followed by two hexadecimal digits. If the string contains a bare "100%", the decoder finds nothing usable after the sign and stops. A literal percent sign has to be written %25.

Worked example

A search phrase in a query string

Input: a b&c

Output: a%20b%26c

Note: The ampersand becomes %26 so it cannot be mistaken for the start of the next parameter — precisely the bug you get without encoding.

Useful links

All tools in Dev Tools

URL Encoder / Decoder

Result

Related tools

Base64 Encoder / Decoder

Query String Parser

UTM Link Builder

HTML Entities Encoder

Useful links