Base64 changes how bytes are represented. It does not encrypt them. Anyone with the encoded string can attempt to decode it, so an encoded password is still a password that has been exposed.
Use Base64 Encoder & Decoder for small standard Base64 or Base64url exchanges. The tool can encode text or decode a supplied string, with strict checks on the alphabet and padding.
A known text example
Encoding hello with standard Base64 gives aGVsbG8=. Decoding that value should return hello. This is a useful quick check when two systems disagree about the representation.
Base64url uses a different alphabet for two characters and commonly omits padding. Select the appropriate variant instead of editing a token by guesswork. The tool checks whether the encoded bits have a canonical representation.
Whitespace in an encoded value is tolerated, but invalid alphabet characters or an impossible length are not silently accepted. An error is a reason to inspect the source, not to delete random characters until something appears.
Decoded output is not always readable text
Some encoded data represents binary bytes. If the result is not display safe UTF8, the tool shows hexadecimal instead of forcing those bytes into a text editor.
Hex output describes the decoded bytes; it is not the same representation as the original Base64 input. Keep track of which format the next application needs.
This tool is for short data strings. For a whole photo that needs a data URI, use the image category's dedicated Base64 tool, which also defines its image reencoding behaviour.
Do not paste a live authentication secret merely to inspect it. The PHP server receives the input. A harmless example is enough to check whether your integration expects ordinary Base64, the URL variant or plain decoded text.