Base64 Encoder and Decoder
Turn text or a file into Base64, or Base64 back into text or a file. Emoji and accents come through intact, and a bad character is pinpointed.
Encoded as UTF-8. Up to 10,000,000 characters.
Standard Base64 on one line, as data URLs need, whatever the options above.
Everything runs on your device: what you type, paste or choose never leaves it, and nothing is saved.
Base64 in both directions, done carefully
Base64 writes any bytes with 64 safe characters (A to Z, a to z, 0 to 9, + and /), so binary data can travel through systems built for text: JSON, XML, email, HTML and URLs. You meet it in API keys, email attachments, data URLs for small images and the parts of a JSON Web Token. This tool encodes and decodes it exactly, and says precisely what’s wrong when it can’t.
How to use it
- Pick what to do: text to Base64, Base64 to text, a file to Base64, or Base64 back to a file.
- Type or paste into the box, or choose a file up to 10 MB. The result appears as you type.
- When encoding, turn on URL-safe, padding or line breaks if the place you’re pasting into needs them.
- Copy the result, or download it. For Base64 to a file, check the suggested name, then press Download file.
The options
- URL-safe uses - and _ instead of + and /, for links, file names and tokens.
- Padding adds = signs so the length is a multiple of 4. Some systems need it; JSON Web Tokens leave it out.
- Line breaks every 76 characters follow the email (MIME) format. Leave this off for JSON, URLs and code.
When decoding fails
The decoder skips spaces and line breaks and accepts missing padding. Anything else that isn’t Base64 is reported with its character number, line and column, and Select the bad character highlights it in the box. Common culprits: an invisible zero-width space picked up while copying, a % left by URL encoding, or the dot between the parts of a token.
Good to know
- Base64 isn’t encryption. Anyone can decode it, so never use it to hide a password.
- Text is encoded as UTF-8, the encoding the web uses, so emoji and accents survive the round trip. Decoded bytes that aren’t text are offered as a file instead, with a guess at the file type.
- A pasted data URL works too: the decoder reads its type and uses it to name the file you download.
- Big inputs are fine: up to 10 MB of data. The boxes show the first million characters; Copy and Download always use all of it.
- A data URL makes an image about a third bigger. Shrink it first with the Image Compressor; for site icons, the Favicon Generator makes proper files.
- Everything runs on your device: nothing is uploaded, sent or saved.