IGES viewer online
Open IGES files instantly — measure in mm, cut a section, spot overhangs and check if the model is ready to print. Nothing is uploaded.
What is a IGES file?
IGES was first published in 1980 by the US National Bureau of Standards, with participation from Boeing, General Electric and others, as one of the earliest standards for moving CAD data between different systems. Files use the .igs or .iges extension and are fixed-width 80-column text records divided into Start, Global, Directory Entry, Parameter Data and Terminate sections, a layout that reflects its punched-card heritage. IGES describes wireframe curves, trimmed and untrimmed NURBS surfaces, and, in later revisions, solids, but in practice it is mostly used for surface data. The format has not been updated since version 5.3 in 1996; STEP replaced it as the preferred standard. Even so, aerospace, automotive and tooling companies keep large IGES archives, and some CAM and surface-modelling programs still ask for it.
What a IGES file can store
An IGES file stores geometric entities defined in a directory: lines, arcs, splines, NURBS curves and surfaces, trimmed surfaces, and in some cases B-rep solids. It also records a model-space unit in its global section, plus layers, colour numbers and simple assembly via instancing. A file often contains surfaces that are not stitched into a closed solid, so the shape may have gaps between patches. Parametric history, product structure data and manufacturing annotations are not standardised.
Apps that open IGES
SolidWorks, Rhino, FreeCAD, Autodesk Inventor, Fusion, CATIA, Siemens NX, Mastercam, AutoCAD, Onshape.
Strengths
- Understood by decades of CAD and CAM software
- Good for exchanging NURBS surfaces and curves
- Declares the model unit in the file
- Plain text that can be inspected
Limits
- Superseded by STEP and no longer updated
- Surface sets often arrive unstitched, with gaps
- Weaker support for solids, assemblies and colour
- Fixed 80-column text layout is bulky
IGES and 3D printing
IGES is not a printing format, and slicers do not open it. The file must be tessellated to STL or 3MF first, and the surface-only nature of many IGES files creates the main difficulty: if patches are not stitched into a closed shell, the resulting mesh has holes and slicers report it as non-manifold. When that happens, stitch or sew the surfaces in your CAD program, or run a mesh repair afterwards. MeshShift reads IGES and IGS through OpenCascade in the browser, with draft, normal or fine tessellation, and then offers the print check to find open edges and rebuild a closed solid at the same size. It does not write IGES; STEP is the better target for CAD.
Frequently asked questions
How do I open a IGES file without installing software?
Drop the IGES file on this page. It opens in your browser with studio lighting and real dimensions; nothing is uploaded. You can rotate, zoom, measure between two points, cut through the model and check whether it is watertight for printing.
Is IGES the same as IGS?
Yes. IGS is the three-letter extension used by systems that limited file names, and IGES is the full form. They contain the same data, and software that opens one will open the other, so renaming a .igs to .iges is safe.
Should I use IGES or STEP to exchange CAD files?
Use STEP whenever the receiving software supports it. STEP handles solids, assemblies, colours and units more reliably. IGES is still the right choice for surface-only exchanges and for older CAM tools that were never updated to read STEP.
Can MeshShift open IGES files for 3D printing?
MeshShift reads IGES and IGS in your browser and converts them to STL, 3MF and other mesh formats, with selectable tessellation quality. It cannot write IGES. If the surfaces do not form a closed shell, use the print check to find the gaps and rebuild a solid.