URL Encoder & Decoder | Free Online Percent-Encoding Tool

What is URL Encoding?

URL encoding, also known as percent-encoding, is a method for translating special characters in a Uniform Resource Locator (URL) into a format that is universally understood and safely transmitted across the internet. URLs have a very restricted character set. Any character that is not part of this "safe" set—such as spaces, slashes, or question marks when used in a query parameter—must be encoded. This is done by replacing the character with a `%` sign followed by its two-digit hexadecimal equivalent.

Our URL Encoder & Decoder is a free online tool that allows you to perform this critical conversion instantly, ensuring your URLs are always valid and correctly interpreted by web browsers and servers.

What Problem Does This Tool Solve?

Imagine you have a URL for a search query like: `https://example.com/search?q=what is c++?`. This URL contains characters like spaces and a second question mark that have special meanings. If sent as-is, a web server might misinterpret it, breaking the search functionality. The space could be read incorrectly, and the second `?` could be seen as the start of a new, unexpected parameter.

URL encoding solves this ambiguity. It converts the problematic characters into a safe format that servers understand. For example, the space becomes `%20` and the `+` becomes `%2B`. This ensures that the URL is transmitted exactly as intended, without corruption or misinterpretation. Our tool automates this process, saving developers and users from the complex task of manually identifying and converting each special character, which is crucial for building reliable web applications and APIs.

How to Use Our URL Encoder / Decoder?

Our tool is designed for maximum efficiency:

Select the Mode: Choose either the "URL Encode" or "URL Decode" tab based on your needs.
Enter Your String:
- To Encode: Paste the full URL or a string of text containing special characters into the input box. The tool will instantly show you the properly encoded version.
- To Decode: Paste a percent-encoded URL or string (e.g., one you copied from your browser's address bar) into the input box. The human-readable, decoded version will appear immediately.
Copy the Result: Click the "Copy Output" button to grab the converted string for use in your code, browser, or documents.

If you enter an invalid encoded string (e.g., a `%` not followed by two hex digits), the tool will show an error, helping you debug your input.

Benefits of Using Our URL Encoding Tool

Ensure URL Validity: Create correctly formatted URLs that work reliably across all browsers and servers.
Prevent Errors and Bugs: Avoid common issues in web development caused by unencoded characters in query strings and API calls.
Improve Readability: Quickly decode long, confusing, percent-encoded URLs to understand their parameters and values.
Instant and Accurate: Get RFC 3986 compliant encoding and decoding in real-time as you type.
Completely Secure: All operations are performed in your browser. Your data is never sent to our servers, ensuring your URLs and data remain private.
Developer's Best Friend: An essential utility for anyone working with web development, API testing, or data transmission over HTTP.

In-Depth Use Cases

For Web Developers Building Links

A developer is creating a "Share on Twitter" link. The text to be tweeted is "Check out my new article & win prizes!". The `&` character is a reserved character in URLs. To ensure it's treated as text, the developer encodes the string, which becomes `Check%20out%20my%20new%20article%20%26%20win%20prizes!`. They can now safely insert this into the `https://twitter.com/intent/tweet?text=` URL.

For API Testers

An API tester is sending a GET request to an endpoint that requires a date parameter in ISO format, like `2024-10-26T10:00:00+05:30`. The `+` sign can be misinterpreted as a space. They use the URL encoder to convert it to `2024-10-26T10%3A00%3A00%2B05%3A30`, ensuring the server receives the correct timestamp.

For Data Analysts and SEOs

An analyst copies a long URL from their web analytics platform. It's filled with `%` codes representing campaign names and search queries. To make it readable for a report, they paste it into the URL Decoder, instantly converting strings like `utm_campaign=Summer%20Sale` into `utm_campaign=Summer Sale`.

Key Features Explained

Encode/Decode Tabs: A simple interface lets you switch between the two primary functions effortlessly.
`encodeURIComponent()` Function: Our tool uses the standard JavaScript `encodeURIComponent()` function, which is designed to encode characters that have special meaning in URLs. It encodes all characters except for `A-Z a-z 0-9 - _ . ! ~ * ' ( )`.
`decodeURIComponent()` Function: For decoding, we use the corresponding `decodeURIComponent()` function, which correctly interprets the percent-encoded sequences and converts them back to their original characters.
Client-Side Processing: The entire tool is powered by JavaScript running on your local machine. This makes it incredibly fast and guarantees that your potentially sensitive URL parameters are never transmitted over the network.

Best Practices & Pro-Tips

Encode Only the Components: Do not encode an entire URL (e.g., `https://example.com`). This will incorrectly encode the `/`, `:`, and `?` characters that are necessary for the URL's structure. You should only encode the individual values of query string parameters. For example, in `?name=John Doe`, you only encode `John Doe`.
Spaces can be `+` or `%20`: In query strings, you may see spaces represented by a `+` sign. This is from an older standard. Our decoder correctly handles both `+` and `%20` as spaces. For encoding, `%20` is the modern and more consistent standard.
Use for All User-Generated Content: Any time you are taking user input and placing it into a URL, you should encode it to prevent errors and potential security issues like Cross-Site Scripting (XSS).
Check for Double Encoding: Be careful not to encode a string that has already been encoded. This can lead to characters like `%` becoming `%25`, resulting in a corrupted string (e.g., `%20` becomes `%2520`).

Technical Deep Dive: Reserved vs. Unreserved Characters

The standard that governs URLs (RFC 3986) divides characters into two main categories:

Unreserved Characters: These characters are always safe to use and have no special meaning. They are: `A-Z`, `a-z`, `0-9`, `-`, `_`, `.`, `~`.
Reserved Characters: These characters have a special, predefined meaning for the structure of the URL. They include:
- General Delimiters: `: / ? # [ ] @`
- Sub-Delimiters: `! $ & ' ( ) * + , ; =`

URL encoding is the process of taking a reserved character that you want to use as *data* (not for its special meaning) and converting it into its percent-encoded form. For example, if you want the text `&` to be part of a search query, you must encode it to `%26`. If you don't, the browser will interpret it as a separator for a new URL parameter.

The process is simple: take the character's ASCII/UTF-8 value, convert it to a two-digit hexadecimal number, and prepend a `%`. For example, the `&` character has an ASCII value of 38, which is `26` in hexadecimal. Thus, it becomes `%26`.

Frequently Asked Questions (FAQ)

1. What is the difference between `encodeURI` and `encodeURIComponent`?: `encodeURI` is a "gentler" function that does not encode the reserved characters (`:`, `/`, `?`, `&`, etc.), assuming you are passing it a full, valid URI. `encodeURIComponent` is more aggressive and encodes these characters. Our tool uses `encodeURIComponent` because it is the correct and safer choice for encoding individual URL parameter values.
2. Why do some websites use `+` for spaces?: Using a `+` to represent a space is part of an older encoding standard (`application/x-www-form-urlencoded`), often seen in HTML form submissions. The modern standard (RFC 3986) uses `%20`. Our decoder correctly handles both for convenience.
3. Is URL encoding a security feature?: While it is a critical part of preventing certain types of security vulnerabilities (like XSS), it is not a security feature on its own. Its primary purpose is to ensure data integrity during transport. You should always combine it with other security practices like input validation.
4. Can I encode an entire file this way?: No. URL encoding is designed for strings of text. To embed a file in a data URI, you should use Base64 encoding. Check out our Base64 Encoder / Decoder for that.
5. Is my data safe with this tool?: Yes. Our tool is 100% client-side. The encoding and decoding logic runs entirely in your browser, so the data you enter is never sent to our servers.

Base64 Encoder / Decoder: For encoding binary data or files, which is often needed alongside URL encoding in web development.
JSON Schema Validator: If you are passing a JSON objects as URL parameters, use this tool to ensure your JSON is valid.
QR Code Generator: Create a QR code from your properly encoded URL to make it easily scannable.