How to save a decoded Base64 image on a Mac
You can do this with B64 in one click, and the file you get is byte-for-byte the one that was encoded. Here is how, and how to prove it.
Decoding shows you the picture. Saving turns it back into a file you can open, attach, edit or archive — and the file you get is not a re-rendering or a conversion. It is the original bytes.
There is no purchase and no account for any of this, and no time limit on it. Encoding and Batch are the paid features; turning Base64 back into a picture is not.
Save it
Decode the payload
Paste it into Decode (⌘2). Raw Base64, a data URI, or a payload inside HTML, CSS or Markdown all work.
Click Save…
The Save panel opens with an extension already chosen from what the bytes actually are, not from what a data URI claimed.
Choose where it goes
Anywhere you like —
/Users/you/Downloads/, a project folder, wherever you keep assets. Nothing is written until you confirm.
What is written
The decoded bytes, exactly as they came out. No re-compression, no colour conversion, no metadata stripped, no metadata added. If the source was a JPEG from a camera, the file you save has the same EXIF, the same compression and the same checksum as that JPEG.
When a data URI declares image/png and the payload is really a JPEG, the file is saved as a JPEG. Naming it .png would produce a file that misleads every program that opens it.
Proving it round-tripped
Open the Inspector (⌥⌘I) and look at the SHA-256 of the decoded bytes. Compare it against the checksum of the original file — which you can get by loading that file into Encode and reading its Inspector.
If the two match, the file is identical. That is not a strong indication; it is proof. See how to get the SHA-256 checksum of an image.
Saving many at once
A folder of Base64 text files can be decoded and saved in a single pass with Batch (⌘3), which restores the original names automatically. See how to convert a folder of Base64 files to images.
Other things to do with the result
- Quick Look to check it at full size before committing it to disk.
- Copy Image to paste it straight into another app without a file at all.
Troubleshooting
The Save button is not available
Nothing has decoded yet. Check the inline note beside the input — an invalid or truncated payload has nothing to save.
The extension is not the one I expected
The bytes disagreed with the declaration. The Inspector shows both; the saved file follows the bytes, which is the only choice that produces a file that works.
The saved file will not open
The payload was truncated before it reached you. Compare the character count with the source, or compare checksums. A partial file is a partial file however it is named.
Frequently asked questions
Is the saved file identical to the original?
Yes, byte for byte. Nothing is re-compressed or re-rendered, so metadata, compression and checksum all match the file that was encoded.
How do I prove it is identical?
Compare the SHA-256 of the decoded bytes in the Inspector against the checksum of the original file. Matching checksums are proof, not an indication.
Why did it save as .jpg when the data URI said PNG?
Because the bytes are a JPEG. Saving it as .png would produce a file that misleads every program that opens it.
Can I save a whole folder of payloads at once?
Yes — Batch decodes a folder in one pass and restores the original names.