URL Encoder Decoder

Convert special characters, spaces, Unicode, and reserved symbols to URL-safe percent-encoding (%XX format per RFC 3986) and decode percent-encoded strings back to readable text — essential for building query strings, API parameters, redirect URLs, and UTM campaign links.

URL Encoder Decoder: Paste text to URL-encode it (spaces become %20, & becomes %26), or paste an encoded URL to decode it back to readable form. Essential for constructing query strings and debugging URL parameters.

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Key Takeaways

Encodes special characters as %XX hex values per RFC 3986
Space encodes as %20 (URL) or + (form data)
Common encodings: & → %26, = → %3D, / → %2F, ? → %3F
UTF-8 characters encode as multi-byte sequences (%E2%9C%93)
Essential for building query strings, API calls, and redirect URLs

What is URL Encoder Decoder?

URL Encoder Decoder — A URL Encoder/Decoder is a free tool that converts special characters in URLs to percent-encoded format (%XX) and decodes encoded URLs back to readable text.

This free URL encoder and decoder converts text to URL-safe percent-encoded format and decodes percent-encoded strings back to readable characters — all in your browser with no server processing. Encode spaces (%20), ampersands (%26), equals signs (%3D), slashes (%2F), question marks (%3F), and any special or Unicode characters into RFC 3986-compliant percent-encoding for use in query strings, API request parameters, redirect URLs, OAuth callback URLs, and UTM campaign tracking links. The behavior matches JavaScript's encodeURIComponent() and decodeURIComponent() functions exactly. Decode URL-encoded strings from analytics tools, server logs, API responses, ad platform tracking URLs, and email marketing redirect chains to inspect the original human-readable values. Detect and fix double-encoding issues (%2520 instead of %20) that break links and corrupt tracking data.

How to Use URL Encoder Decoder

1
Paste plain text, query parameter values, or Unicode characters into the Encode panel to convert them to URL-safe percent-encoded format (%XX hex values).
2
Paste a percent-encoded URL string into the Decode panel to convert it back to human-readable text with all special characters restored.
3
Review the output to verify correct encoding — check that spaces become %20, ampersands become %26, and UTF-8 characters produce proper multi-byte sequences.
4
Copy the encoded or decoded result with one click for use in API requests, query strings, redirect URLs, analytics parameters, or application code.

Key Features

RFC 3986-compliant percent-encoding for all reserved characters, special symbols, and Unicode text

Full decoding of %XX hex sequences, multi-byte UTF-8 encodings, and mixed encoded/plain strings

Live real-time encoding and decoding as you type — no submit button needed

One-click copy for both encoded and decoded output ready for API calls, URLs, and code

Matches JavaScript encodeURIComponent()/decodeURIComponent() behavior exactly

100% client-side processing — your URLs and data never leave the browser

Use Cases

Encoding query parameter values with special characters before appending them to API endpoints and REST URLs

Decoding percent-encoded redirect URLs from Google Ads, Facebook Ads, email marketing platforms, and analytics tracking links

Debugging URL-encoded payload values in server logs, API request/response bodies, and webhook data

Building UTM campaign tracking URLs with properly encoded utm_source, utm_medium, and utm_campaign parameter values

Encoding file paths, search queries, and user input containing spaces, slashes, and Unicode characters for web applications

About URL Encoder Decoder

What Is URL Percent-Encoding?

URL encoding (formally called percent-encoding) is defined in RFC 3986 as the standard method for representing special characters in Uniform Resource Identifiers (URIs). Every character that is not an unreserved character (A-Z, a-z, 0-9, hyphen, underscore, period, tilde) must be encoded as a percent sign followed by two hexadecimal digits representing the character's byte value. For example, a space becomes %20, an ampersand becomes %26, an equals sign becomes %3D. UTF-8 Unicode characters encode as multi-byte sequences — a checkmark (✓) becomes %E2%9C%93. This ensures URLs remain valid across all browsers, servers, and network infrastructure without ambiguity.

Common Encoded Character Reference

Char	Encoded	When it must be encoded
Space	`%20` or `+`	Always (+ only in query string)
`!`	`%21`	In path / fragment
`"`	`%22`	Always
`#`	`%23`	In values (it's the fragment delimiter)
`$`	`%24`	In query parameter values
`&`	`%26`	In values (it's the parameter delimiter)
`'`	`%27`	Always
`+`	`%2B`	In query (+ means space there)
`/`	`%2F`	In values (it's the path delimiter)
`:`	`%3A`	In values (it's scheme delimiter)
`;`	`%3B`	In path / query values
`=`	`%3D`	In values (it's the key/value delimiter)
`?`	`%3F`	In values (it's the query delimiter)
`@`	`%40`	In user info / values
`%`	`%25`	Always (it's the encoding prefix!)

encodeURI vs encodeURIComponent

JavaScript provides two URL encoding functions with crucial differences:

encodeURI() — encodes characters that aren't part of valid URL syntax. Does not encode structural characters: : / ? # [ ] @ ! $ & ' ( ) * + , ; =. Use to encode a complete URL where structure should be preserved.
encodeURIComponent() — encodes ALL characters except unreserved. Encodes : / ? # @ etc. Use to encode individual values (query parameters, path segments).

The rule: always use encodeURIComponent() for individual values. Use encodeURI() only on complete URLs you want to mostly preserve. The big mistake: calling encodeURI() on a parameter value preserves & and =, breaking the URL structure if the value contains those chars.

+ vs %20 for Spaces

Both + and %20 represent space in URLs, but they're context-dependent:

%20: always works in any URL position (path, query, fragment)
+ (plus sign): only means space in application/x-www-form-urlencoded bodies and query strings. In the path, + is a literal plus character.
encodeURIComponent uses %20; the older escape() used %20; the legacy encodeURIComponent() + form encoding might use either.

Safest: always use %20. Reserve + for form-data contexts where the server explicitly decodes it as space.

Double Encoding Trap

A common bug: encoding an already-encoded URL. %20 (a space) becomes %2520 (literally "%20"), which then decodes to %20, not a space. If you see %25 followed by another hex byte in your output (or %2520, %2526), the data was double-encoded somewhere in the pipeline. Fix: trace the encoding chain. Common culprits: server-side framework auto-encoded a value that was already encoded; URL was concatenated with already-encoded parameter.

Common Use Cases

UTM campaign URLs: encode brand names with spaces / special chars in utm_campaign
API requests: encode user input before appending to query strings
OAuth redirect URIs: the redirect_uri parameter must be percent-encoded
Email subject lines in mailto: links: ?subject=Hello%20World
Webhook URLs in JSON: URLs nested in JSON often need extra encoding layer
QR code data: some QR scanners URL-decode automatically; pre-encoding ensures consistency
Form-data POST bodies: application/x-www-form-urlencoded uses same encoding
Search queries: ?q=hello%20world works universally
File paths in URLs: filenames with spaces / Unicode
Decoding analytics tracking URLs: ad platforms wrap original URLs in tracking redirects

Common Encoding Pitfalls

A frequent mistake is double-encoding values. If you see `%2520`, the value was likely encoded twice. Decode once, verify the original string, then re-encode only where needed.

Typical SEO and Analytics Use

Marketers and SEO teams often use URL encoding for campaign parameters and redirect chains. This tool helps verify UTM values and destination links before publishing.

Frequently Asked Questions

What is URL percent-encoding and how does it work?: Percent-encoding (defined in RFC 3986) replaces characters that are unsafe or reserved in URLs with a percent sign followed by two hexadecimal digits representing the character's byte value. For example, a space becomes %20, an ampersand becomes %26, and a question mark becomes %3F. This ensures URLs remain valid and parseable across all browsers, servers, and network infrastructure.
What is the difference between encodeURIComponent and encodeURI in JavaScript?: encodeURIComponent() encodes all characters except unreserved characters (A-Z, a-z, 0-9, -, _, ., ~), making it ideal for encoding individual query parameter values. encodeURI() preserves URL structural characters like ://?#[]@!$&'()*+,;= and only encodes characters that are completely invalid in URLs. This tool follows encodeURIComponent() behavior for maximum encoding safety.
Why does a space encode as %20 sometimes and + other times?: In standard URL percent-encoding (RFC 3986), spaces encode as %20. In application/x-www-form-urlencoded format (used by HTML form submissions), spaces encode as +. Most modern APIs and JavaScript's encodeURIComponent() use %20. If you see + in URLs, it's typically from form-encoded data or legacy systems.
What is double URL encoding and how do I fix %2520 errors?: Double encoding occurs when an already-encoded string is encoded again. For example, a space (%20) gets re-encoded to %2520 because the % sign itself is encoded to %25. To fix this, decode the string once to get the single-encoded form, identify where the duplicate encoding occurs in your code pipeline, and ensure encoding happens only once at the output boundary.
How do I encode Unicode and special characters in URLs?: Unicode characters are first converted to their UTF-8 byte representation, then each byte is percent-encoded. For example, the euro sign is encoded as %E2%82%AC (three UTF-8 bytes). This tool handles all Unicode characters automatically, producing correct multi-byte percent-encoded sequences.
Can I use this tool to encode UTM parameters and campaign tracking URLs?: Yes. Encode individual UTM parameter values (utm_source, utm_medium, utm_campaign, utm_content, utm_term) that contain spaces, ampersands, or special characters before appending them to your tracking URL. This prevents broken analytics attribution and ensures Google Analytics, Adobe Analytics, and other platforms correctly parse your campaign data.
Is this URL encoder decoder free and is my data stored?: Yes, completely free with no signup required. All encoding and decoding runs 100% client-side in your browser — your URLs, query strings, and data are never uploaded to any server or stored anywhere.

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Use Cases

Encoding query parameter values with special characters before appending them to API endpoints and REST URLs

Decoding percent-encoded redirect URLs from Google Ads, Facebook Ads, email marketing platforms, and analytics tracking links

Debugging URL-encoded payload values in server logs, API request/response bodies, and webhook data

Building UTM campaign tracking URLs with properly encoded utm_source, utm_medium, and utm_campaign parameter values

Encoding file paths, search queries, and user input containing spaces, slashes, and Unicode characters for web applications

Char

Encoded

When it must be encoded

Space

%20 or +

Always (+ only in query string)

!

%21

In path / fragment

"

%22

Always

#

%23

In values (it's the fragment delimiter)

$

%24

In query parameter values

&

%26

In values (it's the parameter delimiter)

'

%27

Always

+

%2B

In query (+ means space there)

/

%2F

In values (it's the path delimiter)

:

%3A

In values (it's scheme delimiter)

;

%3B

In path / query values

=

%3D

In values (it's the key/value delimiter)

?

%3F

In values (it's the query delimiter)

@

%40

In user info / values

%

%25

Always (it's the encoding prefix!)

Frequently Asked Questions

What is URL percent-encoding and how does it work?

Percent-encoding (defined in RFC 3986) replaces characters that are unsafe or reserved in URLs with a percent sign followed by two hexadecimal digits representing the character's byte value. For example, a space becomes %20, an ampersand becomes %26, and a question mark becomes %3F. This ensures URLs remain valid and parseable across all browsers, servers, and network infrastructure.

What is the difference between encodeURIComponent and encodeURI in JavaScript?

encodeURIComponent() encodes all characters except unreserved characters (A-Z, a-z, 0-9, -, _, ., ~), making it ideal for encoding individual query parameter values. encodeURI() preserves URL structural characters like ://?#[]@!$&'()*+,;= and only encodes characters that are completely invalid in URLs. This tool follows encodeURIComponent() behavior for maximum encoding safety.

Why does a space encode as %20 sometimes and + other times?

In standard URL percent-encoding (RFC 3986), spaces encode as %20. In application/x-www-form-urlencoded format (used by HTML form submissions), spaces encode as +. Most modern APIs and JavaScript's encodeURIComponent() use %20. If you see + in URLs, it's typically from form-encoded data or legacy systems.

What is double URL encoding and how do I fix %2520 errors?

Double encoding occurs when an already-encoded string is encoded again. For example, a space (%20) gets re-encoded to %2520 because the % sign itself is encoded to %25. To fix this, decode the string once to get the single-encoded form, identify where the duplicate encoding occurs in your code pipeline, and ensure encoding happens only once at the output boundary.

How do I encode Unicode and special characters in URLs?

Unicode characters are first converted to their UTF-8 byte representation, then each byte is percent-encoded. For example, the euro sign is encoded as %E2%82%AC (three UTF-8 bytes). This tool handles all Unicode characters automatically, producing correct multi-byte percent-encoded sequences.

Can I use this tool to encode UTM parameters and campaign tracking URLs?

Yes. Encode individual UTM parameter values (utm_source, utm_medium, utm_campaign, utm_content, utm_term) that contain spaces, ampersands, or special characters before appending them to your tracking URL. This prevents broken analytics attribution and ensures Google Analytics, Adobe Analytics, and other platforms correctly parse your campaign data.

Is this URL encoder decoder free and is my data stored?

Yes, completely free with no signup required. All encoding and decoding runs 100% client-side in your browser — your URLs, query strings, and data are never uploaded to any server or stored anywhere.

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URL Encoder Decoder

Key Takeaways

What is URL Encoder Decoder?

How to Use URL Encoder Decoder

Key Features

Use Cases

About URL Encoder Decoder

What Is URL Percent-Encoding?

Common Encoded Character Reference

encodeURI vs encodeURIComponent

+ vs %20 for Spaces

Double Encoding Trap

Common Use Cases

Common Encoding Pitfalls

Typical SEO and Analytics Use

Frequently Asked Questions

URL Encoder Decoder