Free tool
Base64 Decoder
Turn a Base64 string back into what it was.
Base64 strings turn up in places you did not put them: an API response, a JWT payload, a config file, a data URI in some CSS, an email header. Decoding one tells you whether it holds a line of JSON, a PNG, or something that should not have been there at all.
Paste the string and the decoded result appears as you type. If the bytes are valid UTF-8 you get readable text; if they are binary — an image, a PDF, a compiled asset — there is nothing sensible to display, so you get the decoded size and a download instead.
How to use it
- 01Paste the Base64 string into the box.
- 02Read the decoded text, or download the file when the content is binary.
- 03Copy the result if you need it elsewhere.
Frequently asked questions
It says my string isn't valid Base64. Why?
Usually a stray character that isn't part of the alphabet, or a fragment of a longer string. Line breaks and spaces are fine — they are ignored — and so are the URL-safe characters `-` and `_` and a missing `=` at the end, all of which this tool accepts.
Why do I get a download instead of text?
Because the decoded bytes are not valid UTF-8 text — the string encoded a file, not a sentence. Downloading it and opening it is the way to see what it is.
Can I decode part of a JWT with this?
Yes, a JWT is three Base64url segments separated by dots — paste one and it will decode. For the whole token at once, the JWT decoder shows the header, payload and expiry properly.
Is the string sent anywhere?
No. Decoding happens in this tab, which matters here because Base64 in the wild often carries tokens or personal data. Nothing you paste is transmitted — only an anonymous “decoded something” count.
Related tools
- Base64 EncoderEncode text or a file to a Base64 string.
- JWT DecoderDecode a JWT's header and payload, and check its expiry — signature is not verified.
- File Extension / MIME Type LookupLook up what a file extension or MIME type actually means.
- File Hash / Checksum GeneratorGenerate SHA-1, SHA-256 or SHA-512 checksums for a file or a piece of text.
This is what Purgify automates.
Connect your cloud accounts and Purgify finds duplicates and reclaimable space like this — across all of them, on a schedule.
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