Base64 Encoded String

Matches a valid Base64-encoded string with proper padding using = characters.

✓ File upload validation✓ API token parsing✓ Image data URIs

Test String

No matches

SGVsbG8gV29ybGQ=
dGVzdA==
YWJjZGVmZ2g=

^^— ^ — start of string (or line in multiline mode)

(?:…)*Non-capturing group— Non-capturing group — groups without capturing (no index assigned) — repeated zero or more times (greedy) · * — zero or more times (greedy)

[…]{4}Character class […]— Matches any single character listed in this set — repeated exactly 4 times · {4} — exactly 4 times

(?:…)?Non-capturing group— Non-capturing group — groups without capturing (no index assigned) — repeated zero or one time (optional) · ? — zero or one time (optional)

[…]{2}Character class […]— Matches any single character listed in this set — repeated exactly 2 times · {2} — exactly 2 times

==— '=' — literal character

||— | — alternation: matches expression on left OR right

[…]{3}Character class […]— Matches any single character listed in this set — repeated exactly 3 times · {3} — exactly 3 times

==— '=' — literal character

$$— $ — end of string (or line in multiline mode)

Pattern: 67 charsInput: 38 chars

100% client-side · private

✓ Valid Examples

SGVsbG8gV29ybGQ=
dGVzdA==
YWJjZGVmZ2g=

✗ Invalid Examples

SGVsbG8gV29ybGQ
not!base64@string
YWJjZGVmZ2g===