ASCII Characters Only
URLs can only contain a specific set of characters from the ASCII set. Any character outside this set must be encoded.
URL Encoder & Decoder
Easily encode or decode URL strings and components. Our tool uses encodeURIComponent for safe, browser-based processing. Perfect for developers dealing with query strings and special characters.
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A URL encoder/decoder converts text between plain text and URL-safe format. URL encoding (also called percent encoding) replaces special characters like spaces, ampersands, and non-ASCII characters with percent-prefixed hex codes (e.g., space becomes %20). This ensures URLs work correctly in browsers and APIs. Decoding reverses this process. This tool handles both operations instantly in your browser.
Encode and decode URLs without sending data anywhere
Uses `encodeURIComponent` for maximum safety. Process query strings, path segments, and special characters — all locally in your browser. No uploads, no limits.
100% client-side
Instant results
Free unlimited
How to use
- 1
Paste Your String
Enter the text or full URL you want to process into the 'Input String' field.
- 2
Choose an Action
Click the 'Encode' button to convert special characters into their percent-encoded format, or click 'Decode' to revert them back to their original form.
- 3
Copy the Result
The processed string will appear in the 'Output' field. Click the 'Copy Result' button to save it to your clipboard.
Why is URL Encoding Necessary?
Reserved Characters
Characters that have a special meaning in URLs (like `&` or `?`) must be encoded to avoid being misinterpreted by the server.
Data Integrity
Encoding ensures that parameters passed in the URL (e.g., search queries) are interpreted correctly as data, not as part of the URL structure.
Security
Proper encoding prevents URL injection attacks and ensures that user-supplied data does not break or manipulate the URL.
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Understanding URL Encoding
What is URL encoding and why is it needed?
URLs were originally designed to transmit ASCII text over the internet. The URL specification (RFC 3986) reserves certain characters for special purposes: '?' separates the path from the query string, '&' separates parameters, '=' separates keys from values, '#' marks a fragment, and '/' separates path segments. When these characters appear in the data portion of a URL (like a search query or a parameter value), they must be encoded to avoid being interpreted as structural delimiters.
URL encoding (percent encoding) replaces each reserved or non-ASCII character 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 forward slash becomes %2F. Characters in the unreserved set (A-Z, a-z, 0-9, hyphen, underscore, period, tilde) are never encoded. The JavaScript function encodeURIComponent() handles this encoding, while decodeURIComponent() reverses it.
Modern URLs also need to handle Unicode characters (emoji, CJK characters, accented letters). These are first encoded as UTF-8 bytes, then each byte is percent-encoded. For example, the coffee emoji 鈽?(U+2615) is encoded as UTF-8 bytes E2 98 95, which becomes %E2%98%95 in a URL. The browser and server automatically handle this encoding when you type a URL or submit a form, but developers often need to manually encode or decode URLs when building API endpoints, redirect URLs, or data URIs.
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Common use cases for URL encoding
URL encoding is essential when passing data through URLs in web applications. Common scenarios include: building API query parameters (encoding search terms, filter values), creating redirect URLs that contain the original URL as a parameter (e.g., /login?redirect=%2Fdashboard), generating data URIs for embedded images or fonts, and encoding email links with subject and body parameters (mailto:?subject=...&body=...). OAuth flows also heavily rely on URL encoding for state parameters and callback URLs.
A common bug is double-encoding -- encoding an already-encoded string. For example, encoding '%20' would produce '%2520' (the percent sign itself gets encoded to %25). Always decode before re-encoding if you're unsure of the string's current state. Another common issue is using encodeURI() instead of encodeURIComponent() -- encodeURI() does not encode reserved characters like ?, &, and =, making it unsuitable for encoding parameter values. Use encodeURIComponent() for individual parameter values and encodeURI() only for complete URLs.
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How does this compare to other URL encoders?
A side-by-side comparison of popular URL encoding tools.
| Feature | NovaTools | URL-Encoder.io | MeyerWeb |
|---|---|---|---|
| Encode + Decode in one tool | Both modes | Encode only | |
| Live conversion as you type | Instant | Submit button | |
| Handles Unicode/emoji | UTF-8 | Limited | |
| Privacy (no upload) | 100% local | Server-side | |
| Copy with one click | |||
| Works offline | (static page) |
Our tool performs all encoding and decoding in your browser -- your text is never sent to a server, making it safe for URLs containing sensitive parameters like tokens or session IDs.
FAQ
What is URL Encoding?
URL encoding, also known as percent-encoding, is a mechanism for converting characters that have a special meaning in URLs (like spaces, '&', '?', '#') into a safe format that can be transmitted over the internet. Each special character is replaced by a '%' sign followed by its two-digit hexadecimal ASCII code. For example, a space becomes `%20`, an ampersand becomes `%26`, and a hash symbol becomes `%23`. Without encoding, these characters would be misinterpreted by web servers and browsers, causing broken links, incorrect query parameters, or security vulnerabilities like URL injection attacks.
Is my data sent to a server?
No. This tool operates entirely within your web browser. Your data is never uploaded or stored on any server, ensuring 100% privacy and security. The encoding and decoding operations use JavaScript's built-in `encodeURIComponent()` and `decodeURIComponent()` functions, which run locally in your browser's JavaScript engine. There are no network requests, no server-side logging, and no analytics tracking your input. This makes the tool safe to use for sensitive data like API keys, session tokens, or proprietary URLs that you do not want exposed in server logs.
What's the difference between encodeURI() and encodeURIComponent()?
This tool uses `encodeURIComponent()`, which is generally safer and more thorough. It encodes reserved characters that are essential to the URL's structure (like `/`, `?`, `&`, `#`) to ensure they are treated as literal text, whereas `encodeURI()` preserves them. Use `encodeURIComponent()` when encoding a single query parameter value (e.g., `?q=` + encodeURIComponent(searchTerm)). Use `encodeURI()` only when encoding a complete URL that already has a valid structure. Using the wrong function can lead to broken URLs or, worse, security vulnerabilities like query string injection.
When should I use URL encoding?
URL encoding is necessary whenever you include data in a URL that contains characters outside the ASCII character set or characters that have special meaning in URL syntax. Common scenarios include: encoding search query parameters (e.g., `?q=hello world` → `?q=hello%20world`), encoding email addresses or usernames in URLs, passing JSON or base64 data in query strings, encoding international characters (UTF-8), and building redirect URLs with nested parameters. If you are building URLs programmatically in JavaScript, always use `encodeURIComponent()` on dynamic values.
What characters need to be encoded?
Characters that must be encoded include: reserved characters with special meaning in URLs (`;`, `,`, `/`, `?`, `:`, `@`, `&`, `=`, `+`, `$`, `#`), unsafe characters that could be misinterpreted (`<`, `>`, `"`, `{`, `}`, `|`, ```, `^`, `~`, `[`, `]`), and non-ASCII characters (any character outside the basic ASCII range 0-127). Spaces are always encoded as `%20` (not `+`, which is a common misconception — `+` is only used for spaces in `application/x-www-form-urlencoded` data, not in URLs). The percent sign itself (`%`) must be encoded as `%25`.
Can this tool handle Unicode and international characters?
Yes. The tool uses `encodeURIComponent()`, which properly encodes Unicode characters using UTF-8 percent-encoding. For example, the Chinese character `你` is encoded as `%E4%BD%A0` (three bytes in UTF-8), and the emoji `🎉` is encoded as `%F0%9F%8E%89` (four bytes). This ensures that international text, emoji, and other non-ASCII characters are correctly transmitted in URLs. When decoding, the tool uses `decodeURIComponent()`, which converts the percent-encoded bytes back to the original UTF-8 characters.
Why does my decoded URL look different from the original?
This can happen for several reasons. First, `+` characters in the input are not converted to spaces by `decodeURIComponent()` — they remain as literal `+` signs. If you need to decode form-encoded data where `+` represents a space, use `decodeURIComponent(input.replace(/`+/g, '%20'))` instead. Second, if the original URL was encoded with a different character set (e.g., Latin-1 instead of UTF-8), the decoded characters may appear garbled. Third, double-encoding (encoding an already-encoded string) will produce `%2520` instead of `%20` — always decode first, then re-encode if needed.
Does this tool work with Base64 encoding?
This tool focuses on URL encoding, not Base64 encoding. However, the two are often used together: you Base64-encode binary data (like images or tokens), then URL-encode the result to safely include it in a URL. If you need Base64 encoding, use our dedicated Base64 Encoder/Decoder tool. If you have a Base64 string that contains `+`, `/`, or `=` characters and you want to put it in a URL, paste it here and click Encode — those characters will be percent-encoded to `%2B`, `%2F`, and `%3D` respectively.
100% Client-Side Processing
This tool runs entirely in your browser using JavaScript's built-in `encodeURIComponent()` and `decodeURIComponent()` functions.
- We do not upload, store, or analyze your data.
- Everything you process stays on your device.
- There are no server-side logs capturing your input, no analytics tracking what URLs you encode or decode, and no persistent storage of any kind.
- The tool does not use cookies, local storage, or session storage.
- When you close the browser tab, all input and output data is cleared from memory immediately.
This makes the tool safe to use for sensitive data like API keys, session tokens, OAuth redirect URLs, proprietary endpoints, and authenticated links that you do not want exposed in server logs or network traffic captures.
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