Base64 Encoder & Decoder

What is Base64?

Base64 is a way of representing any data, including binary data, using only 64 printable characters: A to Z, a to z, 0 to 9, plus + and /. The = sign is used as padding at the end. It exists so that data can travel safely through systems designed for plain text, such as email, JSON, XML, HTML and HTTP headers.

Common uses include embedding small images in web pages as data URLs, sending file attachments in email, storing binary values in JSON, and the header and payload sections of JSON Web Tokens, which our JWT decoder reads for you. HTTP Basic authentication also sends the username and password Base64-encoded.

How Base64 encoding works

The encoder takes the input three bytes (24 bits) at a time and splits them into four groups of 6 bits. Each 6-bit group is a number from 0 to 63, which is mapped to one character of the Base64 alphabet. If the input length is not a multiple of three, one or two = characters are added as padding. For example, Hello encodes to SGVsbG8=.

Because every 3 bytes become 4 characters, Base64 output is about 33% larger than the original data. That overhead is the price of being able to send binary data as plain text, so Base64 is best for small payloads rather than large files. Our guide what is Base64 encoding covers when it is and is not the right choice.

UTF-8 support and URL-safe Base64

Base64 works on bytes, not characters, so text must first be converted to bytes. This tool encodes text as UTF-8, which means characters such as é, ü, Chinese or Arabic script and emoji are handled correctly. For example, café encodes to Y2Fmw6k=. When decoding, the bytes are read back as UTF-8 so the original text is restored exactly.

Standard Base64 uses + and /, which have special meanings in URLs, and = padding, which also needs escaping. The URL-safe variant replaces + with - and / with _, and this tool also removes the trailing = padding. Use it for values placed in query strings, paths, file names or tokens. For ordinary text in URLs, percent-encoding with the URL encoder is usually the better choice.

Base64 is encoding, not encryption

Base64 does not protect data. Anyone can decode a Base64 string instantly without a key, so it should never be used to hide passwords, API keys or personal information. If you need confidentiality, use proper encryption, and to fingerprint data rather than hide it, a hash generator creates a one-way digest. That said, this tool runs entirely in your browser and nothing you enter is uploaded or stored.