File Splitter and Joiner
This file splitter works right in your browser: drop a file, choose a part size or a number of parts and save the pieces one by one – ideal when a file is too big for an email attachment or an upload limit. You can also join numbered parts back into one file. Nothing is uploaded.
Source: W3C File API – Blob.slice(): sub-ranges of a file without copying (splitting and joining in the browser). Updated: .
How it is calculated
Splitting a file means cutting it into several pieces that can later be put back together into the original. It helps when an email provider, an upload form or a storage medium only accepts files up to a certain size.
How splitting works
- By part size: you say how large a part may be at most, for example 10 MB. The last part is usually smaller.
- By number of parts: the file is cut into the number of parts you want, as equal in size as possible.
- Naming: the parts are named like the original file with a running extension, for example
film.mkv.001,film.mkv.002. Other programs such as 7-Zip understand this convention too. - No upload: splitting happens in the browser. The parts are views into the file; nothing is copied or sent to a server.
Joining parts
Select all parts together. The tool recognizes the numbers (.001, .part1 or _001), puts them in the right order and warns about missing parts. The joined file gets the original name. To check that the file is unchanged after joining, compare its checksum with the hash generator; how long a transfer takes is shown by the download time calculator. To pack several files together there is the ZIP tool.
Frequently asked questions
How do I split a large file?
Drop the file into the box, choose “Split a file”, enter a part size or a number of parts and click “Split file”. Then save the parts one by one or all in a row.
How do I put the parts back together?
Switch to “Join parts”, select all parts together and click “Join parts”. The tool orders the parts by number and returns the complete file for saving.
Is my file uploaded?
No. Everything happens in the browser on your device. The file never leaves your computer and no server sees it.
How large can the file be?
Up to 8 GB. The parts are views into the original file and need no extra memory at first. When joining very large files it depends on your browser and free disk space.
Can I join the parts with other programs?
Yes. The extensions .001, .002 and so on are recognized by 7-Zip, for example. On Windows the command copy /b file.001+file.002 file also works, on Linux and macOS cat file.* > file.
Sources and legal basis
- W3C File API – Blob.slice(): sub-ranges of a file without copying (splitting and joining in the browser)
- MDN – Blob: constructor with multiple parts (concatenation)
As of: · Editorial policy
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