What is Base64 encoding?

Base64 is a way of representing binary data (or text) using only 64 printable ASCII characters: A–Z, a–z, 0–9, +, and /. It's designed so binary data can be safely transmitted through text-based systems like email and JSON without corruption.

Is Base64 the same as encryption?

No. Base64 encoding is not encryption — it provides no security or confidentiality. Anyone can decode Base64 text instantly, since it uses a fixed, publicly known alphabet. Use it for data formatting, never for protecting sensitive information.

What is URL-safe Base64?

Standard Base64 uses + and / characters and = padding, which have special meaning in URLs. URL-safe Base64 replaces + with -, / with _, and removes the padding, so the result can be used directly in a URL path or query string.

Why does decoding say my Base64 is invalid?

Usually one of three things: characters were lost or added when copying; the text uses the URL-safe alphabet (- and _), so turn on URL-safe before decoding; or the Base64 holds a binary file such as an image. Decode mode outputs UTF-8 text only, so binary data can’t be shown.

Can I encode a whole file, not just text?

Yes. Switch to File mode, drop in a file up to 5 MB, and this tool will convert its raw bytes into a Base64 string or a ready-to-use data URI you can paste directly into HTML or CSS.

Why is my Base64 output longer than the input?

Base64 encodes every 3 bytes of input as 4 characters of output, so encoded data is roughly 33% larger than the original. This overhead is the trade-off for representing arbitrary binary data as plain text.