What is the MODFEM file format?
A .modfem file is the native model file created by Femap, the finite element analysis pre- and post-processor sold today as Simcenter Femap by Siemens Digital Industries Software. Femap is short for Finite Element Modeling And Postprocessing. One .modfem file holds an entire project: the geometry (built on the Parasolid kernel), the finite element mesh of nodes and elements, material and element properties, loads, constraints, the analysis setup, and any solver results imported for review.
The extension arrived with Femap version 9, where it replaced the older .mod extension. That history is why you still find both on disk in long-running engineering projects. The format is proprietary binary data, and Siemens has not published a specification for it, so it is not human-readable and has no documented signature. Femap runs only on Windows, which means .modfem files show up almost entirely on Windows engineering workstations.
Security & safety
RISK: MEDIUMA .modfem is a data file, not an executable, so it does not run on its own. However, Siemens advisory SSA-997732 documents a parsing vulnerability in the Femap .modfem reader in versions before V2021.2 that a malicious file could exploit. Keep Femap updated and be cautious opening .modfem files from untrusted sources.
Format details
in a nutshell- ModFEM (open-source FEM framework) - ModFEM is the name of an academic modular finite element method framework (Cracow University of Technology), unrelated to the Siemens Femap file extension. It is a software project, not a file type.
Programs that open MODFEM files
Windows2 apps
Simcenter Femap
Paid Open Femap and use File > Open, then select the .modfem file to load the full model tree for editing, meshing, and postprocessing.
Simcenter Femap free trial
Freemium Install the time-limited Siemens trial when you only need to inspect a .modfem file you received, then open it through File > Open. Technical details
deep spec| Encoding | Binary |
| Byte order | Little-endian (Windows-native application) |
| Container | Proprietary single-file model database |
| Compression | None documented; data stored in an internal structured layout |
| Encryption | None by default |
| Typical size | Hundreds of KB to several GB depending on mesh density and result data |
| Structure | A single .modfem file holds the complete Femap model tree: imported or native geometry (via the Parasolid kernel), the finite element mesh (nodes and elements), material and property definitions, loads and constraints organized into load and constraint sets, analysis setup, and optionally imported solver results for postprocessing. |
| Integrity | No public integrity/checksum scheme documented |
| Platforms | Windows |
| Notes | Proprietary and undocumented. The .modfem extension replaced the older .mod extension starting with Femap version 9. Femap runs on Windows only, so .modfem files are practically Windows-bound. Siemens security advisory SSA-997732 documents a parsing flaw in the .modfem reader in Simcenter Femap before V2021.2, confirming the format is parsed directly by the application. |
| Released | Femap version 9 (mid-2000s) |
| Latest version | Simcenter Femap (2020s releases) |
| Specification | www.siemens.com |
MODFEM conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about MODFEM files.
Frequently asked questions
How do I open a .modfem file?
Is there a free viewer for .modfem files?
What is the difference between .modfem and .mod files?
.mod extension was used by older Femap versions, and .modfem replaced it starting with Femap version 9. Recent Femap versions open both.
