Base64 Encoder / Decoder

Mode Encode text → Base64Decode Base64 → textFile → data URI / Base64 URL-safe (JWT-style: -/_, no padding)

Input

Convert

What this tool does

Encodes any text (full Unicode, via UTF-8) to Base64 and back. Standard output carries padding; the URL-safe variant uses - and _ and drops padding, exactly as JWTs and URL parameters expect. Decoding is forgiving where it is safe to be — both alphabets, whitespace and line breaks ignored, missing padding accepted — and anything else is refused with the exact character position. Decoded bytes that are not valid text are offered as a binary download instead of being mangled.

Why local matters here

Base64 strings are very often credentials: session tokens, API keys, basic-auth headers, JWT segments. Pasting them into an online converter that uploads to a server is how secrets leak. This page is static, has no server in the loop, and keeps working with the network disconnected — verified by our automated tests on every release.