File Joiner
Rejoin split file parts back into the original file
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
Drop all parts here or click to select them
Files ending in .part1, .part2, …
About this tool
Rejoins file parts that were previously split (using the File Splitter or a similar tool) back into the original, complete file - the necessary second step after transferring split pieces through a size-limited channel.
How to use this tool
- Collect all split partsEnsure every chunk from the original split set is available.
- Load parts into joinerImport complete set so tool can reconstruct in sequence.
- Rebuild original fileMerge binary chunks into full file output.
- Validate reconstructed fileOpen or checksum-verify to confirm exact restoration.
Key features
- Restores original file exactly when all parts are present.
- Completes split-transfer workflow safely.
- Avoids command-line complexity for file reassembly.
- Useful for non-technical users receiving chunked files.
Common uses
- Reassembling email-transferred split archives.
- Reconstructing large media moved via small USB chunks.
- Recovering distributed backup pieces into original file.
- Validating integrity after segmented transfer process.
Tips for better results
- Keep original part filenames and sequence unchanged.
- Verify all parts have completed downloads before joining.
- Compare resulting file size against source expectation.
- Use checksums for high-value or sensitive outputs.
Mistakes to avoid
- Attempting join with one missing/corrupted part.
- Loading parts from different split sessions together.
- Ignoring part order mismatch warnings.
- Assuming partial join output is usable.
Frequently asked questions
The tool typically identifies the correct order from the parts' naming/sequencing, but make sure you have ALL the parts from the original split - missing even one part will result in a corrupted or incomplete rejoined file.
Yes - if all parts are present and correctly rejoined, the reconstructed file is byte-for-byte identical to the original file before it was split.
The rejoined file will be incomplete or corrupted - all parts from the original split are required to reconstruct the file correctly.
Yes. Joiner is free for normal use with no account required, and ToolBox does not add a watermark to your result.
Most tools in this category run in your browser so the file stays on your device. If a tool needs a temporary server job, files are handled for that job only and are not kept as a lasting archive.
No install needed. Open Joiner in your browser, add your file or paste your input, then download or copy the result.
Yes on modern mobile browsers. For large files, a desktop browser is usually faster and more reliable.
Try a different quality or format setting, use a smaller input, or open a related tool (for example compress before convert). Keep a copy of the original file before replacing it.
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