File Joiner

What this tool does

File Joiner concatenates multiple selected files, reorderable via up/down controls, into a single downloadable output file, byte for byte, the reverse operation of splitting a file into parts, with everything processed entirely client-side.

A file that was previously split into numbered parts, or several pieces that genuinely belong together as one sequential stream, needs to be joined back into a single file, in the exact right order, to be usable again.

This tool lets you select multiple files, reorder them with simple up/down controls, and concatenate them byte for byte into one downloadable output file, the direct reverse of the Text File Splitter, done entirely in your browser.

How to use File Joiner

1. Select the files you want to join.
2. Use the up/down arrows to put them in the correct order.
3. Enter an Output file name.
4. Press Join files and download.

Tips for better results

• This only produces a usable, meaningful result for files that were genuinely meant to be concatenated in sequence, like parts previously split from one source; joining unrelated files (two separate images, for instance) just produces raw concatenated bytes, not a combined, openable file of that type.
• Order matters enormously, double-check the sequence in the preview list before joining, since an incorrect order will produce corrupted or meaningless output for most formats.
• The output file name and its extension should normally match whatever the original, unsplit file was, since this tool doesn’t infer that automatically.
• For files that were split with this site’s own Text File Splitter, joining them back in their original numeric order reliably reconstructs the original text.

Common use cases

• Reassembling a file previously split into numbered parts back into its original single file.
• Combining several sequential log file segments into one continuous file.
• Concatenating multiple text file fragments into a single combined document.
• Joining binary file parts that were split for size-limited transfer.

Common mistakes to avoid

• Joining files in the wrong order, which for most formats produces a corrupted or meaningless result rather than a usable combined file, always verify the order in the preview before joining.
• Trying to join unrelated files (like two different photos) expecting a sensible combined result; plain concatenation only makes sense for files meant to form one continuous sequence.
• Forgetting to set the correct output file extension, which affects how your operating system and applications will try to open the resulting file.