Files with the .part1 extension are most commonly associated with the PeaZip file archiving software. PeaZip can be used to take a large batch of files and compile them into a single file archive. This archive can then be split into separate volumes to make it easier to distribute the files online or to allow for storage of the archive across multiple disks. When the archive is split into separate volumes, each volume is given its own file extension. The .part1 file extension is given to the first volume of the archive.
The .part1 extension is also used for NetObjects Fusion system files.
Try a universal file viewer
File.org aims to be the go-to resource for file type- and related software information. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files.
If you have additional information about the PART1 file format or software that uses files with the PART1 suffix, please do get in touch - we would love hearing from you.