How to split and join files
- To split, choose a file, then pick the size of each part (such as 25 MB) or how many parts you want.
- Download all parts as a ZIP, or one by one. The ZIP also holds a .sha256 checksum file.
- To join, switch to Join parts, select every part, and press Join and download. If you added the .sha256 file, the result is verified for you.
Parts are named like movie.mp4.001, movie.mp4.002, so they sort correctly and work with the plain cat and copy /b commands. Keep the numbers in the names when you share them.
Questions
Is my file uploaded?
No. The file is cut into parts and joined again by your browser. Nothing is sent to a server.
How do I put the parts back together?
Open this page, choose Join parts, and select all the parts. They are ordered by the number at the end of the name and checked against the SHA-256 checksum. You can also join them yourself: on Windows run "copy /b file.001+file.002 file", and on macOS or Linux run "cat file.* > file".
What is the checksum for?
It is a fingerprint of the original file. After joining, the tool computes the fingerprint of the result. If it matches, every byte is identical. If not, a part is missing, damaged, or out of order.
Why split a file?
Common reasons are email attachment limits, upload caps on forum or chat services, and moving a large file on small drives. Parts of 25 MB or 100 MB fit most limits.
Are the parts usable on their own?
No. A part is just a slice of the bytes, so a video or ZIP will not open until all parts are joined. Text files are the exception, since each part holds a piece of the text.
Credits
Built on hash-wasm (MIT) and fflate (MIT). OneTooling is not affiliated with these projects.