Base64 Decoder
Decode Base64 encoded strings back to plain text or binary data.
Frequently Asked Questions
Why does decoding an image or other binary Base64 string give me gibberish?
The decode path turns Base64 into UTF-8 text using `atob` plus string decoding helpers. It is meant for textual payloads, not for reconstructing binary files or offering a download.
Why do I get `Invalid Base64 string`?
That appears when `atob()` throws during decoding. Common causes are truncated input, bad padding, copied whitespace, or URL-safe Base64 characters that were never converted back to standard `+` and `/`.
Can I paste a JWT or URL-safe Base64 directly into this decoder?
Only if that segment is already valid standard Base64. The tool does not normalize `-` to `+`, `_` to `/`, or add missing padding for you.
Does it decode automatically when I paste text?
No. This UI is manual. Paste the string and click `← Decode`.
Can I move the decoded result back into the input box quickly?
Yes. The shared Base64 tool includes a Swap button, so you can flip input and output without re-copying by hand.