Why convert Base64 back to a file
Once data has been encoded as Base64, whether from an API response, an email attachment, or a data URI embedded in code, you often need to reverse the process and get back the original binary file, ready to open, view, or use normally. This tool decodes Base64 text and packages the result as a downloadable file.
How decoding works
The tool uses the browser's built-in atob function to reverse Base64 encoding back into raw binary data, then wraps that data in a Blob object, the standard way browsers represent binary file-like data, before offering it to you as a download. If your Base64 text includes a data: URI prefix, the tool automatically strips it before decoding, so you can paste either the raw encoded string or a full data URI without needing to edit it first.
Naming the output file
Since Base64 text on its own carries no information about what kind of file it represents or what it should be called, you can specify the output file name, including its extension, in the field provided. Getting the extension right matters because your operating system and applications use it to decide how to open the resulting file, whether that's an image viewer, a PDF reader, or a text editor.
Typical use cases
Developers debugging an API that returns file content as a Base64 string use this to quickly turn that string back into a viewable file. It's also useful for recovering a file from a data URI found in a stylesheet or HTML source, or for decoding an email attachment that was provided as raw Base64 text rather than as a normal file attachment.
What happens with invalid input
If the pasted text isn't valid Base64, perhaps due to a copy-paste error that introduced extra characters or line breaks in the wrong place, the tool reports a clear decoding error rather than producing a corrupted file, so you know immediately that something needs to be checked in the source text.
Step-by-step walkthrough
Paste your Base64 text into the input box, whether raw or with a data: prefix, enter the file name and extension you want for the result, and click Convert. Once the status line confirms successful decoding, click Download to save the file to your device with the exact name you specified.
Privacy and performance
Because the Base64 to File Converter runs as JavaScript inside your own browser tab rather than on a remote server, there's no upload step, no waiting on a network connection, and no copy of your file sitting on someone else's infrastructure afterward. That also means it keeps working exactly the same whether your file is a few bytes or several megabytes, limited only by your own device's memory rather than a server's queue or rate limit. If you ever want to double-check that nothing is being transmitted, your browser's built-in developer tools network tab will show no outgoing request for the file's contents at any point during conversion. This also means the tool keeps working offline once the page has loaded, and closing the tab afterward leaves no copy behind on any server, since one was never made in the first place. That's a meaningful difference from typical online converters, which usually require uploading your file to a remote service before you ever see a result.
Frequently Asked Questions
Can I paste a full data URI instead of raw Base64?
Yes, the tool automatically strips any data:mime;base64, prefix before decoding, so either form works.
How do I control what the downloaded file is named?
Enter the desired file name, including its extension, in the Output file name field before clicking Convert.
What happens if the pasted text isn't valid Base64?
The tool reports a clear decoding error rather than producing a corrupted or empty file.
Does the file extension I choose affect the actual decoded content?
No, the extension only affects how your operating system chooses to open the file; the decoded bytes themselves are unaffected by whatever name you give it.
Is my Base64 text uploaded to a server for decoding?
No, decoding happens entirely in your browser using the built-in atob function.