URL Encoder/Decoder
About URL Encoder/Decoder
The URL Encoder and Decoder converts characters into standard percent-encoded octets (%XX) required by RFC 3986. Web browsers and HTTP servers only accept a restricted set of unreserved ASCII characters in URI strings. Reserved characters (such as &, ?, =, /, #, and spaces) must be encoded when passed inside query parameters to avoid breaking URL structure or injecting malformed query paths. Our client-side URL Encoder and Decoder ensures that your data is perfectly sanitized for web transmission. It uses the robust JavaScript encodeURIComponent and decodeURIComponent APIs under the hood, natively handling emojis, UTF-8 strings, and multi-byte Unicode characters with zero risk of misinterpretation. This tool runs entirely in your browser, keeping potentially sensitive redirect chains and tracking parameters private. It is an indispensable utility for developers constructing complex REST API endpoints, setting up webhook payloads, or simply debugging broken links where rogue characters cause routing failures.
Common Practical Use Cases
Encoding search query parameters with spaces and punctuation for REST APIs
Decoding redirect URLs embedded within analytics tracking links
Formatting webhook callback parameters safely
Constructing safe mailto: links with pre-filled subjects and body text
Building deep linking URLs for mobile applications without syntax collision
How to Use URL Encoder/Decoder
- 1Select Encode or Decode mode.
- 2Paste your URL, query parameter, or plain text string.
- 3The converted URL-safe output is generated in real-time.
- 4Copy the output for use in API endpoints or web redirects.
Practical Worked Examples
Encoding Query String Parameter
search=laptop & mouse ($50)
search%3Dlaptop%20%26%20mouse%20(%2450)
Explanation: Spaces become %20, ampersands become %26, and dollar signs become %24.
Supported Formats & Specifications
Accepted Inputs:
- Plain text strings
- Full URLs
- Percent-encoded query parameters
Generated Outputs:
- RFC 3986 percent-encoded URI strings
- Decoded plain text strings
Key Features & Technical Capabilities
- Percent-encodes special and reserved characters
- Decodes percent-encoded query strings back to human-readable UTF-8
- Handles multi-byte Unicode and emoji characters accurately
- Runs locally in browser JavaScript
Under the Hood: Browser Processing Architecture
- Implements encodeURIComponent and decodeURIComponent with proper error trapping for malformed percent sequences.
- Conforms strictly to UTF-8 encoding standards; each multi-byte character is translated to a corresponding sequence of percent-encoded hex octets.
- Throws a standardized URIError if attempting to decode an invalid or truncated percent sequence.
Browser Limits & Edge Cases
- Full URL encoding should use component mode for query values to avoid breaking the protocol (https://) delimiter.
Common Mistakes to Avoid
- Encoding a full URL with encodeURIComponent instead of just its parameter values, which breaks the protocol slashes (http:// becomes http%3A%2F%2F).
Client-Side Code Formatting & Token Privacy
Isolated Local Script SandboxWith URL Encoder/Decoder, syntax parsing, encoding/decoding, and cryptographic hashing run locally in your browser's JavaScript engine. API keys, JWT tokens, and sensitive payloads never leave your computer. Standard static web assets and client runtime scripts are delivered securely via CDN over encrypted TLS (HTTPS).
Frequently Asked Questions
Why are spaces sometimes encoded as + instead of %20?
In application/x-www-form-urlencoded query strings, spaces are historically encoded as "+", while standard RFC 3986 URI encoding uses "%20". Both are widely accepted by HTTP parsers.
What is the difference between encodeURI and encodeURIComponent?
encodeURI is used for full URLs and leaves characters like "http://", "/", and "?" intact. encodeURIComponent encodes everything, including those protocol characters, making it the correct choice for encoding the values of individual query parameters.
Why does my decoded URL still look weird?
If a URL was encoded multiple times (double-encoded), you may need to run the decode function multiple times to get back to the original text.