Base64 works by taking data 3 bytes at a time and re-representing each group as 4 characters, drawn from a fixed alphabet of 64 text-safe characters (A–Z, a–z, 0–9, plus two symbols) — which is where the name comes from. That 3-bytes-to-4-characters ratio means encoded output is roughly 33% larger than the original for any reasonably long input. Encoding the text "Hello, OneTabKit!" (17 characters) produces SGVsbG8sIE9uZVRhYktpdCE= — 24 characters, a bit more than 33% larger here specifically, because the input length isn't an exact multiple of 3 and needs a padding character (the trailing =) to round out the last group.
Base64 has no secret key and nothing to keep hidden — the alphabet and the rules for converting between bytes and characters are fully public and identical every time, which is exactly what makes it reversible by anyone, instantly, with no password required (as this page demonstrates by decoding it right back). Its actual job is making binary-unsafe data safe to put somewhere that only expects plain text — embedding an image directly inside CSS or HTML via a data URI, or encoding credentials for an HTTP Basic Authentication header are both common real examples. If something needs to stay confidential rather than just survive a text-only channel, that calls for actual encryption, which Base64 was never designed to provide.
It converts binary or text data into a text-safe format, commonly used for embedding data in URLs, emails, or JSON where raw binary isn't allowed.
Yes — this tool correctly handles Unicode text, not just basic ASCII.
No — Base64 is just an encoding format, not encryption. Anyone can decode it back to the original text; it provides no security or privacy protection.