What is Base64URL Encoding?

Base64URL is a URL-safe variant of Base64 encoding defined in RFC 4648. It replaces the standard Base64 characters + and / with - and _ respectively, and removes padding = characters. This makes the encoded data safe to use in URLs, filenames, and other contexts where standard Base64 characters might cause issues.

How to Use

Select "Encode" or "Decode" mode
Enter your text or Base64URL string
The result appears automatically as you type
Click "Copy Output" to copy the result

Example

Standard Base64:

SGVsbG8+IFdvcmxkPw==

Base64URL (URL-safe):

SGVsbG8-IFdvcmxkPw

Key Differences from Standard Base64

URL-Safe Characters: Uses - instead of + and _ instead of /
No Padding: Removes trailing = characters
Safe for URLs: Can be used directly in URLs without encoding
Safe for Filenames: Works in file systems without special handling

Common Use Cases

JWT (JSON Web Tokens) encoding
URL parameters containing binary data
Filenames for cached or temporary files
API keys and tokens in URLs
OAuth and authentication flows
Cookie values containing binary data

UTF-8 Support

This tool properly handles UTF-8 encoding, supporting international characters, emojis, and special symbols in both encoding and decoding operations.

Frequently Asked Questions

What's the difference between Base64 and Base64URL?

Base64URL is a URL-safe variant of Base64. It replaces + with -, / with _, and removes padding = characters. This makes it safe to use in URLs, filenames, and other contexts where standard Base64 characters might be misinterpreted or require additional encoding.

Why is Base64URL used in JWTs?

JWTs (JSON Web Tokens) use Base64URL encoding because tokens are often transmitted in URLs and HTTP headers. Base64URL ensures the token can be safely included in these contexts without requiring additional URL encoding, making implementation simpler and more reliable.

Can I decode standard Base64 with this tool?

No, this tool is specifically for Base64URL format. Standard Base64 strings containing +, /, or = characters will be rejected. Use our standard Base64 Decode tool for regular Base64 strings.

Is Base64URL encryption?

No! Base64URL is an encoding scheme, not encryption. It's easily reversible and provides no security. Anyone can decode Base64URL data. Never use Base64URL alone to protect sensitive information - use proper encryption instead.

Why does the encoded data look different each time?

It shouldn't! Base64URL encoding is deterministic - the same input always produces the same output. If you're seeing different results, you might be encoding different input (like timestamps or random values).

Is my data sent to a server?

No, all encoding and decoding happens in your browser. Your data never leaves your device, ensuring complete privacy and security.