What is File Joiner?

A file joiner reassembles files that were split into multiple parts. Upload the parts in order, and the tool concatenates them back into the original file. Useful when files were split for email attachments, storage limits, or transfers.

Drop in all the parts (.part001, .part002, .001, .002, etc.), drag them into the correct order if the upload sorted them wrong, set the output filename, and the joiner concatenates the bytes into a single Blob and downloads it. The joining is binary-exact, so the reassembled file matches the original byte for byte.

How to use

1. Upload all file parts by dragging them into the drop zone.
2. Put the parts in the correct order by dragging them, or use the up and down arrows on each row.
3. Set the output filename and click join to download the reassembled file.

When to use

• Reassembling a video or archive that was emailed as multiple smaller attachments.
• Restoring an installer ISO that was split with 7-Zip or HJSplit on another machine.
• Recombining backup chunks pulled from a USB stick that ran out of room for one big file.

Result

You received a 500MB video split into five 100MB parts (video.001–video.005). Upload all five, verify the order, and download the complete video.

FAQ

What file naming convention does the tool expect?

It doesn't care about the extension — .001/.002, .part001/.part002, or random names all work because you set the order manually. Pick the right extension from the Set Extension dropdown, or just type the full output filename yourself, including the original extension if you remember it.

How do I know I uploaded the parts in the right order?

Sort them by the numeric suffix the splitter used (most splitters use 001, 002, 003). Use the Auto-Sort by Filename button to do this in one click, then double-check the order against the original sequence. After joining, the file size should match the original and the file should open cleanly — a wrong order produces a file that won't open at all.

Is there a file size limit when joining?

The joiner builds a Blob in memory before triggering the download, so the practical ceiling is roughly the RAM your tab can use — usually a few gigabytes on desktop. A 20 GB join on a phone will probably fail before it starts.

Will this work for parts created by 7-Zip or WinRAR archives?

If the original tool split a single binary into raw byte ranges (.001, .002, …), yes — those concatenate cleanly. If it produced multi-volume .zip or .rar volumes with archive headers, joining them won't help; you need the original archiver to extract.

Are my files uploaded to a server?

No. The parts stay in the page and the concatenation happens locally via the Blob API. The output file is created and downloaded straight from the page — nothing is sent over the network.

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