URL-Safe Base64 Converter
Convert between standard Base64 and URL-safe Base64 format. URL-safe Base64 (also known as Base64url) replaces problematic characters (+ and /) with URL-friendly alternatives (- and _) for use in URLs, filenames, and JSON data.
What is URL-Safe Base64?
Standard Base64 encoding uses the characters A-Z, a-z, 0-9, +, and / with = as padding. However, some of these characters (particularly +, /, and =) have special meanings in URLs and filenames, which can cause problems when using Base64 strings in these contexts.
URL-safe Base64 solves this by replacing:
- + (plus) with - (hyphen)
- / (slash) with _ (underscore)
- Optionally removing = (equals) padding characters
This makes the encoded string safe to use in URLs, filenames, and other contexts where certain characters might cause issues.
Frequently Asked Questions
When should I use URL-safe Base64?
Use URL-safe Base64 when you need to include Base64-encoded data in URLs, filenames, or other contexts where characters like +, /, and = might cause problems. Common use cases include:
- JWT (JSON Web Tokens) and other authentication tokens
- URL parameters and query strings
- File naming in systems with character restrictions
- JSON data where escape characters should be minimized
- HTML data attributes where quotes need to be avoided
Is padding necessary?
Base64 padding (= characters) ensures the encoded string length is a multiple of 4. While technically required for standard Base64, many URL-safe implementations remove padding since it can be reconstructed based on string length. Our tool gives you the option to include or remove padding.
Is this the same as Base64url?
Yes, URL-safe Base64 is also known as "Base64url" as defined in RFC 4648 Section 5. It's the standard way to make Base64-encoded data safe for use in URLs and filenames.
How is URL-safe Base64 used in JWT tokens?
JWT (JSON Web Tokens) use URL-safe Base64 encoding for all three parts of the token (header, payload, and signature). This ensures the entire token can be safely included in URLs, cookies, and HTTP headers without character encoding issues.
Does URL-safe Base64 affect decoding?
When decoding, you need to use the appropriate method for the encoding type. Standard Base64 decoders may fail on URL-safe Base64 strings if they don't first convert the special characters back (- to + and _ to /). Our tool handles this conversion automatically.