Base64 Decoder Developer
Decode Base64 back to readable text, URL-safe input included.
Base64 Decoder is a free online tool that decode Base64 back to readable text, URL-safe input included. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free: no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- None, it just works
- Works offline
- Yes, after the first visit
About Base64 Decoder
Base64 packs three bytes into four ASCII characters, so decoding always shrinks the data by exactly 25%. Trailing `=` signs are padding to a multiple of four and carry no data. If decoding fails, the usual causes are a URL-safe variant using `-` and `_` in place of `+` and `/`, or whitespace and line breaks introduced by an email client; both are handled here before decoding.
How to use it
- Paste the text you want to run through base64 decoder.
- There is nothing to configure: the result updates as you type.
Under the hood
| Runs on | plain JavaScript: runs the whole thing |
Questions
Is Base64 a form of encryption?
No, and treating it as one is a genuine security mistake. It is a reversible encoding with no key, designed to move binary data through text-only channels. Anyone can decode it instantly; this page is proof.
Why does my decoded text have odd characters?
The bytes are probably not UTF-8 text: they may be an image, a compressed blob, or text in another encoding. Base64 carries arbitrary bytes and cannot tell you what they were meant to be.