Base64 represents arbitrary bytes using only 64 safe ASCII characters (A-Z, a-z, 0-9, + and /), which is why it appears everywhere that binary data has to travel through a text-only channel: HTTP Basic auth headers, email MIME parts, JSON payloads, data URIs and JWT segments. This tool converts in both directions and handles UTF-8 correctly, so accented characters, Devanagari text and emoji round-trip without corruption — a common failure in older tools that call btoa() directly on non-Latin input. Encoding inflates the payload by roughly 33%, adding one padding '=' for every missing byte in the final group, so a 300-byte string becomes 400 characters.
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