What is the IAM file format?
Files with the .iam extension are used by the 3D modelling software Autodesk Inventor.
What are the contents of .iam files?
.iam files are created by Autodesk Inventor for storing assemblies - collections of components called parts and sub-assemblies. An .iam file does not embed part geometry directly; instead it holds references (file links) to the individual .ipt part files that make up the assembly, together with data defining the position of each component and its mechanical relations to other components (for example, alignment of mounting screws, bearing fits, and mating faces). Autodesk Inventor allows users to design or modify assemblies saved in .iam files. In this way a user can break a module down into its individual parts and reuse those parts in a new project. Users can also expand sub-assemblies, reposition components, or add new parts to an existing assembly.
Because an .iam file is a container of references rather than a self-contained model, moving or renaming any referenced .ipt file breaks the assembly. To share a complete assembly as a portable package, use Inventor's Pack and Go feature (which gathers all referenced files) or export to a neutral format such as a STEP file.
What are .iam files used for?
Autodesk Inventor is a professional program for creating parametric 3D models of mechanical designs. The assembly environment provided by .iam files not only lets users position modules within a complete design, but also lets them define assembly-level parameters such as joint constraints and motion relationships. Saving designed assemblies in .iam files facilitates component reuse and module-based design across multiple projects.
.iam files use the Microsoft OLE2 Compound File Binary container - the same structured-storage format used by other Inventor file types such as .idw drawings and .ipn presentation files. The format is proprietary and version-specific: assemblies saved by a newer Inventor release cannot be reliably opened by an older version.
Security & safety
RISK: LOWAn .iam is CAD reference/geometry data, not an executable, so opening one in Inventor/Fusion or a viewer is safe. The realistic concerns are non-malware: an .iam references external part files, so a shared assembly often arrives with missing parts (use Pack and Go to gather everything), or fails to open due to a newer Inventor version. An assembly can also embed proprietary, exactly measurable design detail - treat shared files as sensitive. Download Inventor/Fusion and the Autodesk Viewer only from autodesk.com to avoid fake-'IAM viewer' adware sites.
Format details
in a nutshellPrograms that open IAM files
Windows4 apps
Autodesk Inventor
Paid File > Open the .iam to view and edit the assembly with full constraint history. Subscription product; needs the referenced parts present. 
Autodesk Viewer (web)
Free Upload the .iam in a browser (free Autodesk account) to view, rotate and measure without Inventor - the best free way to just look at an assembly. Upload referenced parts too if prompted.
Autodesk Fusion
Freemium Upload/Open the .iam (with its parts) to import the assembly into Fusion for viewing or further modeling. Free for personal/hobby use.
Inventor View / Inventor Read-Only
Free Legacy free Inventor viewer for opening .iam/.ipt read-only; largely superseded by the web Autodesk Viewer. 
macOS2 apps
Autodesk Viewer (web)
Free Inventor has no macOS app - use the browser-based Autodesk Viewer to view an .iam on a Mac.
Autodesk Fusion
Freemium Native macOS app - upload/open the .iam (plus parts) to view or model. Free for personal use.
Autodesk Viewer
Free Drag the .iam (and its referenced parts) onto viewer.autodesk.com to view, measure and share - no install, any OS. Technical details
deep spec| Container format | Microsoft OLE2 / Compound File Binary (structured storage) - the same CFB header used by older Office documents and other Inventor file types |
| Magic bytes | D0 CF 11 E0 A1 B1 1A E1 at offset 0 (OLE2 signature); internal streams identify it specifically as an Inventor assembly |
| Byte order | Little-endian |
| Internal structure | OLE2 compound file holding an assembly tree: file references to component `.ipt` / `.iam` files, assembly constraints and joints, component positions, and metadata streams |
| Part geometry storage | Not embedded in the `.iam` - geometry lives in the referenced `.ipt` part files; the assembly file stores only links and positional data |
| Sub-assembly support | Yes - an `.iam` can reference other `.iam` files as sub-assemblies, enabling multi-level hierarchical assemblies |
| Version compatibility | Version-specific and forward-only: an `.iam` saved by a newer Inventor release cannot be reliably opened by an older Inventor version |
| Typical file size | Tens of KB to several MB (lightweight because part geometry is stored externally in `.ipt` files) |
| Compression | Internal proprietary stream compression; not a general-purpose archive - files cannot be decompressed with standard tools |
| Encryption | None by default; Inventor allows an optional document password on assembly files, but assemblies are normally unencrypted |
| MIME type | application/octet-stream (no registered format-specific MIME type) |
| Portability | Not self-contained; Pack and Go must be used to bundle the `.iam` with all referenced `.ipt` files for transfer, or the assembly can be exported to STEP / IGES for neutral exchange |
| Supported OS | Windows only for Autodesk Inventor; no native macOS desktop application |
| Export formats | Inventor can export `.iam` assemblies to STEP, IGES, `.dwg`, DXF, STL, OBJ, and other neutral or vendor formats |
| Related Inventor file types | `.ipt` (individual part), `.idw` (2D engineering drawing), `.ipn` (exploded-view presentation) |
| Developer | Autodesk |
| Released | 1999 (Autodesk Inventor 1.0) |
| Latest version | Tied to the Inventor release that saved it (e.g. Inventor 2026); no public spec version |
| Specification | www.autodesk.com |
IAM conversions
Community Q&A
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