Base64Url Encoder & Decoder
Encode text to URL-safe Base64 (RFC-4648) or decode Base64Url strings back to readable text.
Encode & Decode Base64Url
Deep Dive: Base64 vs Base64Url
While standard Base64 is great for encoding binary data into ASCII text, it uses two characters that are problematic when placed inside a URL: the plus sign (+) and the forward slash (/). Additionally, it uses the equals sign (=) for padding.
What makes it "URL Safe"?
Base64Url (RFC-4648 Section 5) solves this problem by slightly altering the alphabet:
- Replaces
+with a minus sign- - Replaces
/with an underscore_ - Omits the trailing padding characters
=(optional but strictly required by many parsers like JWT)
Common Use Cases
You will most commonly encounter Base64Url encoding in JSON Web Tokens (JWT). The header and payload of a JWT are encoded in Base64Url so they can be safely passed in HTTP headers or URL query parameters without breaking the web request.
Frequently Asked Questions
Can I decode a standard Base64 string here?
Yes! This decoder is backwards compatible. If you paste a standard Base64 string that contains + or / or padding =, it will still decode it perfectly.
Is Base64Url encryption?
No, Base64Url provides zero security. It is merely an encoding scheme. Anyone can easily decode a Base64Url string. Do not use it to hide sensitive data like passwords.
Why did my JWT token decode fail?
A JWT consists of three parts separated by dots (.). You must copy and decode each part individually (e.g. only the header or only the payload) without the dot character.
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