Question 1

What does the Base64 Encoded String regex pattern do?

Accepted Answer

Matches base64 encoding: groups of 4 base64 characters, with optional padding (= or ==) at the end. Validates proper padding alignment.

Question 2

How do I use the Base64 Encoded String regex in JavaScript?

Accepted Answer

Use the pattern /(?:[A-Za-z0-9+/]{4})+(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?|[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=/g with the String.match() or String.matchAll() method. For example: const matches = text.match(/(?:[A-Za-z0-9+/]{4})+(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?|[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=/g);

Question 3

What regex flags does this pattern use?

Accepted Answer

This pattern uses the global flag (g). The global flag finds all matches in the input, not just the first.

Question 4

Which programming languages support this regex?

Accepted Answer

Fully supported in JS, PYTHON, JAVA, PHP, GO

Question 5

What strings does this regex match?

Accepted Answer

This pattern matches strings like: SGVsbG8gV29ybGQ=, dGVzdA==, YWJjZGVmZw==. It does not match strings like: !@#$, ====, <<>>.

Language	Support
JS	Full support
PYTHON	Full support
JAVA	Full support
PHP	Full support
GO	Full support

Base64 Encoded String

Pattern

Try It

Explanation

Test Strings

Matching

Non-matching

Language Compatibility

Code Snippets

Common Variations

URL-safe base64