URL Encode & Decode - How to Safely Pass Data in URLs

URLs can only contain a limited set of ASCII characters. When you need to include spaces, Unicode, or special characters in a URL, they must be percent-encoded. URL encoding replaces unsafe characters with %XX hex codes - like %20 for a space or%3F for a question mark.

What Gets Encoded?

Characters that are encoded in URLs:

• Reserved characters - : / ? # [ ] @ ! $ & ' ( ) * + , ; = - have special meaning in URLs
• Unsafe characters - spaces, quotes, angle brackets, curly braces
• Non-ASCII characters - Unicode like Chinese, Japanese, emoji - first UTF-8 encoded, then percent-encoded

Characters that are not encoded: letters (A-Z, a-z), digits (0-9), and - _ . ~

Common Encoded Characters

• Space = %20 (or + in query strings)
• & = %26
• = = %3D
• ? = %3F
• / = %2F
• # = %23

When to URL-Encode

• Query parameters - encoding values in ?key=value
• API requests - passing JSON or special characters as URL parameters
• Redirect URLs - embedding one URL inside another
• OAuth flows - state and redirect_uri parameters
• Internationalization - any URL containing non-ASCII characters

URL Encode vs. HTML Entities

These are different encoding schemes for different contexts:

• URL encoding - for URLs: & becomes %26. Use URL Encoder.
• HTML entities - for HTML content: & becomes &. Use HTML Entity Encoder.

Using the wrong encoding is a common source of bugs.

Free Online URL Encoder/Decoder

Use SnapSum URL Encoder/Decoder - encode or decode URLs instantly in your browser. No server processing, no data retention.

• Encode: paste plain text and get URL-encoded string
• Decode: paste encoded string and get readable text
• Handles Unicode and multi-byte characters correctly
• Live encoding as you type

Step-by-Step: URL Encode/Decode

1. Open URL Encoder/Decoder.
2. Paste your text or encoded URL.
3. Click "Encode" or "Decode."
4. Copy the result.

Developer Tip: encodeURIComponent vs. encodeURI

In JavaScript:

• encodeURI() - encodes a full URL, but preserves : / ? # & = (so the URL structure stays intact)
• encodeURIComponent() - encodes a URL component (like a query value), encoding everything including : / ? # & =

Use encodeURIComponent for query parameter values, encodeURI for full URLs.