What is URL encoding (percent-encoding)?

URL encoding, also known as percent-encoding, is a mechanism for translating special characters, spaces, and non-ASCII symbols in a URL into a safe format that can be parsed across the Internet. It replaces unsafe characters with a percent sign (%) followed by two hexadecimal digits.

Why do we need to encode URLs?

URLs can only contain a limited set of characters from the US-ASCII set. Furthermore, characters like '?', '&', '=', and '/' have structural roles in URLs. Encoding prevents syntax confusion when these characters are used as part of data values.

What is the difference between encodeURI and encodeURIComponent?

encodeURI is designed to encode a full, complete URL and preserves structural symbols like http://, paths, and query variables. encodeURIComponent is designed to encode query parameter values and encodes structural characters too, ensuring they don't break the URL parameters hierarchy.

Why do some spaces encode to '%20' and others to '+'?

Modern standards (RFC 3986) require spaces to be percent-encoded as '%20'. However, HTML form submissions traditionally use the 'application/x-www-form-urlencoded' format, which specifies that spaces should be encoded as '+' and actual '+' symbols encoded as '%2B'.

Does this tool upload my URLs to a server?

No, never. This URL Encoder/Decoder runs entirely within your browser using client-side JavaScript. Your text, parameters, paths, and URLs are processed locally and are never transmitted to any API, server, or database.

Live Processing · 100% Local · Multi-Mode

URL Encoder & Decoder

Percent-encode or decode queries, characters, and full URLs instantly. Fully compatible with RFC 3986 and standard form encoding.

Secure local processing No network transmissions

Raw Text / Input0 lines

URL Encoded Result0 lines

Mode:

Developer Resource

Comprehensive Guide to URL Encoding

URL percent-encoding is key to API parameters, query strings, and state parameters. Explore how it works, understand standard parameters, and test examples.

Real-time Output

No submit buttons. Encodes and decodes automatically as you type.

100% Secure & Local

Your inputs are fully parsed in your browser. Absolutely zero uploads.

4 Standards Supported

Toggle between RFC 3986, URI Component, Form-Urlencoded, and IRI.

Unicode Compatible

Robust encoding of emojis, non-ASCII symbols, and multi-byte characters.

Why URL Percent-Encoding Matters

The Uniform Resource Identifier (URI) syntax limits characters in a URL to a set of reserved and unreserved characters. Any character outside this scope (such as spaces, curly braces, and non-English scripts) must be converted before transmission.

When you enter query text containing delimiters (like & or =), the browser needs to distinguish them from structural dividers. Otherwise, nesting query structures would crash. URL encoding safely wraps values by mapping them to their hex representation.

URI Component vs Form Standard

Depending on where you are using the encoded output, different character mappings apply:

Encoding Styles

1. encodeURIComponent (URI Component):
   Encodes everything except: A-Z a-z 0-9 - _ . ! ~ * ' ( )

2. RFC 3986 (Strict):
   Also encodes: ! ' ( ) * to adhere strictly to standards.

3. Form/W3C (application/x-www-form-urlencoded):
   Encodes space as '+' and requires literal '+' to be %2B.

4. IRI (RFC 3987 / Internationalized URI):
   Preserves Unicode bytes as raw characters for readability.

Common Reserved Characters & Encoded Equivalents

These characters have specific roles in URL parsing. Using them raw as content will cause web applications to split parameters incorrectly.

Character	Percent-Encoded Value	Reason for Restriction
Space	%20 (or +)	Spaces are invalid characters in standard URI paths
Forward Slash ( / )	%2F	Reserved as path segment separator
Question Mark ( ? )	%3F	Reserved to demarcate start of query string
Ampersand ( & )	%26	Reserved to separate query parameters
Equals ( = )	%3D	Reserved to assign query parameter key-value pairs
Hash / Fragment ( # )	%23	Reserved to demarcate URL fragment anchors
Colon ( : )	%3A	Reserved for protocol scheme separator (http://)
Plus ( + )	%2B	Reserved as spacer in forms, requires explicit encoding

Interactive Presets

URL Encoding & Decoding Live Presets

Select an example to see input transformations. Copy outputs to try decoding, or copy inputs to try encoding.

Plain Input

hello world & welcome

Encoded Output

hello%20world%20%26%20welcome

💡 Encodes spaces to %20 and reserves the special separator '&' as %26.

How to Encode & Decode URLs Instantly

Select Mode

Toggle between Encode Mode (plain text to URL-safe strings) and Decode Mode (percent-encoded sequences back to readable text).

Type or Paste

Input your text in the top panel. The bottom panel will reflect changes instantly. Clear or copy using buttons in the headers.

Refine Formats

Select encoding formats (URI Component, Strict RFC 3986, IRI, or Form Mode) to generate the exact layout required for your target system.

Security Alert: Encoding ≠ Encryption

It is crucial to remember that URL encoding is not a security measure. E.g., encoding credentials as https://user:pass@api.com does not hide them. It is simply a transmission standard. Any node, router, or client that intercepts the URL can decode the data in milliseconds. Always encrypt sensitive fields using asymmetric keys or transport-layer protocols (TLS/HTTPS).

Developer Use Cases

Nesting return URLs inside query strings for login redirects
Sending state variables or objects in OAuth requests
Building robust API endpoints using text with spaces/symbols
Formatting headers like application/x-www-form-urlencoded payloads
Cleaning tracking query parameters using the built-in analyzer
Extracting readable keys from nested JSON API query blocks

Built-in Tools Features

Dual mode: Live URL Encoding and live URL Decoding
Local browser execution — absolute sandbox privacy
URL query parameter parser and clean JSON dictionary generator
Tracking parameters clean utility (UTM, Facebook parameters, etc.)
Format output for Shell parameters, HTML attributes, and raw JSON strings
Multi-format support including strict RFC 3986 formatting

Frequently Asked Questions

Answers to common questions about URL percent encoding guidelines.

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