What Is Base64?
Base64 is a way to write binary data using 64 ASCII characters. It is encoding, not encryption. Anyone who sees the string can decode it.
Encoding, not encryption
Base64 maps every three bytes to four characters from a 64-symbol alphabet: A–Z, a–z, 0–9, + and /, plus = padding. The mapping is public. There is no key. If you can encode, you can decode.
That is the opposite of encryption, which is designed so only someone with a key can read the plaintext. Treat Base64 as a transport costume for bytes that must travel through text-only channels — email bodies, JSON strings, data URLs — not as a lock.
A tiny example
The ASCII word Hello encodes to SGVsbG8=. Paste either into the Base64 encoder and decoder to see the round trip, including Unicode.
Not the same as URL encoding
Percent-encoding replaces reserved characters in a URL with %HH so a query value does not break the address. Base64 rewrites arbitrary bytes as a longer ASCII string. You sometimes also percent-encode Base64 when it sits in a query, because + and / are awkward in URLs. That second step is URL encoding, explained in what is URL encoding.
FAQ
- Can I hide a password in Base64?
No. Decoding is trivial and requires no key. Use a real secret store or a password manager.
- Why does Base64 end with =?
Padding. The last group of bits may not fill three bytes, so = characters mark the short end. Some systems omit padding; this page accepts either when the rest is valid.
Related guides
How to Encode Base64
Convert text to UTF-8 bytes, then to Base64. The result is longer ASCII, not a secret. Unicode and emoji need the UTF-8 step or they will be corrupted.
How to Decode Base64
Decoding reverses Base64 back to bytes, then to text with UTF-8. Invalid characters should fail loudly. Success does not mean the original message was secret.
Related tools
See all guides.