URL Encoder / Decoder
URL-encode or decode text instantly in your browser.
What is URL Encoder / Decoder?
The URL Encoder / Decoder is an interactive browser tool that takes raw text or URIs as input and produces either a percent-encoded or decoded string as output instantly. It translates characters that have special meaning in Uniform Resource Identifiers (URIs) into their corresponding hexadecimal triplet representations, and vice versa. Web developers use this utility when debugging API requests with query parameters containing spaces or symbols, backend engineers need to inspect raw payloads sent from HTML form submissions, and security analysts review encoded malicious strings in web server access logs. This section addresses common technical nuances regarding percent-encoding rules, character sets, and formatting behaviors within the tool.
How it works
The URL Encoder / Decoder is an interactive browser tool that takes raw text or URIs as input and produces either a percent-encoded or decoded string as output instantly. It translates characters that have special meaning in Uniform Resource Identifiers (URIs) into their corresponding hexadecimal tr
How to use it
- 1Using the browser-based tool requires entering text into the input field and selecting either the encode or decode action to view the converted result instantly.
- 2The interface allows copying the transformed string directly to the system clipboard for immediate use in configuration files, API clients, or browser address bars.
What it can do
- Encoding
- Decoding
- URL Encoding
Use cases
Assumptions and limitations
Assumptions
- privacy: All processing happens locally in your browser
- runtime: Built with browser-native APIs
Limitations
- ['Malformed percent-encodings containing incomplete hexadecimal pairs throw decoding errors.', 'Encoding full URIs breaks structural delimiters like colons, slashes, and question marks.']
Understanding the result
The URL Encoder / Decoder is an interactive web utility designed to convert strings between standard text format and percent-encoding representation compliant with RFC 3986.
Tool details
- Processing happens entirely in your browser.
- No account, no sign-up, and no tracking of your content.
- Verified to work in current browsers.
- Runs locally
- Yes — nothing is uploaded
- Verification
- Verified in modern browsers
- Input
- URL Text, Plain Text
- Output
- Processed Output
Frequently asked
How does this URL encoder tool handle spaces versus plus signs?
The tool handles spaces differently depending on whether you are following RFC 3986 or application/x-www-form-urlencoded specifications. Standard URI encoding converts spaces into the %20 hexadecimal sequence for uniform resource identifiers. Conversely, form-urlencoded rules often substitute spaces with a plus sign (+) for legacy compatibility with HTML form submissions. Users should verify which format their specific backend parser or API endpoint expects before transmitting data. Selecting the appropriate encoding standard prevents parsing errors on the server side.
What happens when you decode a string with UTF-8 multi-byte characters?
UTF-8 multi-byte characters are represented in URLs as consecutive percent-encoded triplets, such as %C3%BC for a German umlaut. The decoding function reads these adjacent hexadecimal pairs and reconstructs the original Unicode character correctly. If the byte sequence is invalid or incomplete according to UTF-8 rules, the decoder triggers a URIError exception. This ensures that non-ASCII international domain names and query parameters render accurately in the output interface.
How can I prevent double encoding when passing parameters through multiple systems?
Double encoding occurs when an already percent-encoded string is passed through an encoder a second time, turning percent signs into %25. To avoid this issue, always check if your input text already contains encoded characters before applying the tool. If you see characters like %2F or %3F in your raw string, you should decode the input first rather than encoding it further. Recognizing these patterns helps maintain clean URI structures and prevents broken links in web applications.
Can I encode an entire web address or should I only encode query parameters?
You can technically paste an entire web address into the tool, but you must be careful which specification is applied. Encoding a full URL will convert structural characters like forward slashes, colons, and question marks into %2F, %3A, and %3F. This transformation breaks the URL structure and typically results in routing errors when accessed in a browser. Best practices dictate that you should isolate individual query parameter values and encode only those specific segments.
Why does the decoder throw an error when processing certain strings?
The decoder throws a URIError when it encounters a percent sign that is not followed by two valid hexadecimal digits. For example, a string ending with a trailing percent sign or containing malformed hexadecimal pairs like %2G will fail decoding. To resolve this error, inspect your input text for truncated strings or stray percent symbols. Correct the malformed sequence by supplying the missing hexadecimal characters or removing the isolated percent sign entirely.