Base64 Encoder / Decoder

Base64 converts arbitrary binary data into a string of only 64 printable ASCII characters (A-Z, a-z, 0-9, +, /), which is safe to embed in contexts that only handle text — email attachments, JSON payloads, URLs, data: URIs for inline images, and HTTP authentication headers. It's an encoding for safe transport, not a form of encryption or compression.

No — Base64 is fully reversible by anyone with no key required; decoding is trivial and instant, as this tool demonstrates. Never use Base64 to 'hide' or protect sensitive data like passwords or tokens. It only exists to make binary-safe data representable as plain text, nothing more.

Base64 processes input in 3-byte chunks and produces 4 output characters per chunk. When the input length isn't a multiple of 3, padding characters (=) are added to fill out the last group — one = for a remainder of 2 bytes, two == for a remainder of 1 byte. The padding is a marker for decoders, not part of the actual data.

The most common cause is that the string was copied incompletely or has stray whitespace/line breaks inserted (common when Base64 is split across multiple lines in email or config files) — remove line breaks and confirm nothing was truncated. It can also happen if the string uses URL-safe Base64 characters (- and _ instead of + and /) and needs converting to standard Base64 first.

Standard Base64 uses + and / as two of its 64 characters, both of which have special meaning inside a URL, so they'd need to be percent-encoded if embedded directly. URL-safe Base64 replaces those two characters with - and _ instead, so the result can be dropped directly into a URL path or query string without additional encoding. Padding (=) is also sometimes omitted in URL-safe contexts since it can conflict with query-string syntax.