Deep Dive: URL Encoder & Decoder
URL encoding (percent-encoding) follows RFC 3986: characters outside the unreserved set (A-Z, a-z, 0-9, - _ . ~) get converted to %XX hexadecimal. JavaScript's encodeURIComponent() does this, transforming spaces to %20, ampersands to %26, etc. It's essential for query parameters—'key=value&other=data' breaks if 'value' contains an unescaped &. Decoding reverses the process using decodeURIComponent(). Some characters (/, :, ?) have special meaning in URLs, so encoding depends on context: encodeURI() preserves them for full URLs, encodeURIComponent() escapes everything for parameters. This tool uses the component version.
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Privacy Architecture
This tool uses client-side WebAssembly to ensure your data never touches a server. Secure, fast, and privacy-focused by design.
Core Capabilities
- Encode text to URL-safe format (encodeURIComponent)
- Decode URL-encoded strings (decodeURIComponent)
- Real-time conversion as you type
- Handles special characters and emojis (multi-byte UTF-8 → %XX%XX%XX)
- One-click copy/paste
- Follows RFC 3986 percent-encoding rules
- Secure client-side processing
- Free tool, works offline
Why It Matters
- Reliability: Ensure your query parameters are valid and won't break parsing.
- Debugging: Easily read encoded query parameters from browser DevTools or logs.
- Security: Prevent XSS by encoding user input before embedding in URLs.
- Speed: Instant results without server round-trips or external libraries.
- Privacy: Your data (API keys, sensitive params) never leaves your browser.
Quick Start Guide
Choose 'Encode' or 'Decode' mode.
Type or paste your text into the input box.
The result appears instantly using encodeURIComponent() or decodeURIComponent().
Click the copy icon to save the result to your clipboard.
Use the 'Clear' button to start over.
Usage Examples
Encode Spaces in URL
Scenario 01Spaces become %20 in URLs
Hello World
Hello%20World
Encode Query Parameters
Scenario 02Special characters in search queries
name=John Doe&email=john@example.com
name%3DJohn%20Doe%26email%3Djohn%40example.com
Decode URL Parameters
Scenario 03Make encoded URLs readable again
product%3Dlaptop%26price%3D%24999
product=laptop&price=$999
Common Scenarios
Building Search URLs
Encode user search queries for URLs safely.
Debugging API Requests
Understand what's actually being sent to the server.
Email Campaign Links
Create tracking URLs with parameters.
Sharing URLs with Special Characters
Share links containing non-English text.
Questions?
Technical Architecture
Reserved vs Unreserved Characters
**Unreserved** (safe, don't need encoding): A-Z, a-z, 0-9, -, _, ., ~ **Reserved** (special meaning, encode if used as data): : / ? # [ ] @ ! $ & ' ( ) * + , ; = **Everything else**: MUST be encoded (spaces, unicode, etc.) When in doubt, encode it! Better safe than broken URLs.
Percent-Encoding Format
Each encoded character becomes %XX where XX is hexadecimal: - Space: %20 - #: %23 - &: %26 - =: %3D - ?: %3F For Unicode: First convert to UTF-8 bytes, then encode each byte. Example: € → UTF-8: [E2, 82, AC] → %E2%82%AC
When to Encode What
**Path** (example.com/path/to/page): Encode spaces, special chars, but NOT forward slashes **Query string** (example.com?key=value): Encode EVERYTHING except & (separator) and = (assignment) **Fragment** (example.com#section): Encode special characters, rarely used Different parts, different rules! Know where your data goes.
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