Base64 is a binary-to-text encoding that represents arbitrary bytes using a 64-character alphabet of letters, digits, plus, and slash. It exists because many older systems (email headers, URLs, JSON strings, HTTP headers) only accept printable ASCII characters. Wrapping binary data in Base64 lets you transport raw bytes through those systems without corruption, at the cost of a 33 percent size increase. This tool converts in both directions: text or pasted bytes go to Base64, and Base64 strings get decoded back to their original representation. The conversion happens entirely in your browser, so nothing you paste leaves your machine. Useful for debugging API tokens, decoding JWT payloads, inspecting data URLs in image src attributes, examining hashed cookies, or reading the contents of an Authorization header pasted from a server log.
Frequently asked questions
No. Base64 is reversible by anyone with no key required. It is encoding, which changes the representation of data, not encryption, which protects it. Treat any Base64 string as readable to anyone who possesses it.