What is the BPN file format?
.bpn is a backup file format used by ARCHICAD, a BIM modeling and project delivery application developed by Graphisoft. ARCHICAD saves project data in .pln files, which are the base for generating .bpn project backup files.
.bpn files are generated automatically for each project file according to ARCHICAD's data security settings, such as backup copy retention time. .bpn files are saved in the same folder as .pln files and always represent the state of the project one save behind the current .pln - capturing building elements, views, library links and settings in full. The file is structurally identical to a .pln; its version is tied to the ARCHICAD release that created it, so opening a .bpn in an older version of the software is not supported.
.bpn data can be restored by simply renaming the file's suffix to .pln. It is a fast and easy way to recover data in such cases as a corrupted or damaged main project file. File sizes typically mirror those of the source project, ranging from under 1 MB to several hundred megabytes for complex models. ARCHICAD is available on both Windows and macOS.
Security & safety
RISK: LOWA .bpn is just your own project data and is not executable, so it poses no malware risk on its own. Practical caution: do NOT delete the .bpn while the project is active - it is your only one-save-old backup. When recovering, work on a COPY (rename the copy to .pln) so you don't lose the backup if something goes wrong. Avoid generic "BPN viewer" download sites - no real third-party viewer exists; only ARCHICAD opens it.
Format details
in a nutshell- Backup Plus / Burn4Free playlist (.bpn) - A few unrelated apps reuse .bpn for their own backup/playlist data; not interchangeable with ARCHICAD backups.
Programs that open BPN files
Windows2 apps
ArchiCAD
Paid Copy the .bpn, rename it to .pln, then File > Open in ARCHICAD (same or newer version). 
BIMx / ARCHICAD demo
Free Use a trial/educational ARCHICAD to open the renamed .pln if you don't own a license. 
macOS1 app
Technical details
deep spec| Developer | Graphisoft |
| File encoding | Binary (proprietary) |
| Container format | ARCHICAD proprietary project container |
| Internal compression | Proprietary; same scheme as the source .pln |
| Encryption | None by default; inherits password protection if the source project had it |
| Supported platforms | Windows, macOS |
| Typical file size | Under 1 MB to several hundred MB - mirrors the source .pln |
| Content | Full ARCHICAD project snapshot: building elements, views, library links and model settings |
| Backup trigger | Automatic on each project save, governed by ARCHICAD data security settings |
| Recovery method | Rename .bpn to .pln, then open in ARCHICAD |
| File location | Always stored in the same directory as the corresponding .pln |
| Version compatibility | Version locked to the ARCHICAD release that created it; older releases cannot open it |
| Snapshot depth | One save behind the current .pln (previous project state) |
| MIME type | application/octet-stream |
| Related formats | .pln (active project), .pla (solo archive), .bpc (backup copy archive), .mod (module) |
| Released | ARCHICAD (Graphisoft BIM software, present for many releases) |
| Latest version | Tied to the ARCHICAD version that created it (e.g. ARCHICAD 28, 2024) |
| Specification | help.graphisoft.com |
BPN conversions
Community Q&A
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