What Is an STP File?

How to open, edit, and convert STP Files

Screenshot of several STP files
STP Files.

A file with the .STP or .STEP file extension is most likely a STEP 3D CAD file saved in the Standard for the Exchange of Product Data (STEP) format. They contain information regarding 3D objects, and are typically used to transfer 3D data between different CAD and CAM programs.

An STP file could also be a RoboHelp Stop List file, which is a plain text file up to 512 characters long that contains a list of words the associated Smart Index wizard should ignore when making a search index for help docs.

For example, words like "or" and "a" are ignored from documentation searches to avoid showing non-relevant information.

Microsoft SharePoint uses STP files too, but for template documents. Like any template, the STP file serves as a way to quickly start making a web page using a similar design as another.

An STP file may instead be an XML-based Analysis Studio Project Information file that holds various settings and objects for Analysis Studio projects.

Note: STP is also an acronym for some non-file extension terms like software test plan, scheduled transfer protocol, secure transfer protocol, system test procedure, and shielded twisted pair.

How to Open an STP File

There are a number of software programs that can open STEP 3D CAD files, but Autodesk Fusion 360 is the most versatile since it runs on Windows, macOS, and mobile devices, including through a web browser.

Some other STP file openers that work with this CAD file format include FreeCAD, ABViewer, TurboCAD, CATIA from Dassault Systemes, and IDA-STEP.

There's also a free online STEP/STP viewer from ShareCAD.org.

Adobe RoboHelp opens STP files that are for stop lists.

You can use Microsoft's SharePoint for opening STP files that are SharePoint Template files.

Tip: You can create new STP files in SharePoint through Site Settings > Administration > Go to site Administration, and then Save site as template in the Management and Statistics area.

Appricon's Analysis Studio program opens STP files that belong to that software, but we don't have any valid download links for it. There is this one from CNET.com, but there isn't any way to purchase the program or use the trial version, so it's basically useless. We've only included it here in case you happen to find a way to make it work.

How to Convert STP Files

The STEP 3D CAD software from above should also be able to convert the file to other formats, especially Autodesk Fusion 360. You can usually find the conversion tool in a Save as or Export menu/button.

You can also easily convert STP or STEP files to STL using 3D Transform or Makexyz. They're both online STEP 3D CAD file converters, so they work with any operating system.

CrossManager is another STP file converter but it doesn't work online; you have to install it to your computer in order to use it. However, it supports many more export formats in addition to STL, like PDF, OBJ, PRT, VDA, SAT, 3MF, MODEL, and others.

Note: The trial version of CrossManager will only convert to 3D or 2D PDF. The other formats are available if the full program is purchased.

The trial version of ConvertCADFiles.com can convert STP to PDF but only if it's less than 2 MB.

If it's smaller than 12 MB, you can try the free CoolUtils.com.

The FreeCAD program mentioned above should be able to convert STP to OBJ as well as DXF.

Read this thread at Stack Overflow for information on converting STEP files to DWG.

If your STP file is in a different format that doesn't pertain to a 3D CAD file format, consider using the software that opens the file (linked in the previous section above) to convert it to a new file format. For example, SharePoint is most likely the best best program for converting SharePoint Template files.

Is Your File Still Not Opening?

If you can't get your file to open with the programs mentioned above, or can't convert it with any of the tools mentioned on this page, chances are good that you're not actually dealing with an STP file in any of these formats.

The first thing you should do is double-check that the file extension truly reads STP or STEP (if you have a CAD-related file) and not something that's just spelled similarly like STE. With suffixes that sound or spell like STP, do not immediately assume that the file formats can be used with the same applications.

In the STE example, the file opens with programs like Adobe Dreamweaver and Samsung Image Viewer since it could be either a Dreamweaver Site Settings file or a Samsung IPOLIS Image file.

STR is another example that belongs to the dBASE Structure List Object file format and opens with dBase. It could instead be in other formats like PlayStation Video Stream, X-Plane Object String, BFME2 Strings, Kingsoft Strings, or Windows Screensaver File.

As you can see, you need to make sure that the file is actually related to the programs from above, else they can't be expected to open it. If your file isn't an STP or STEP file, research the actual file extension to learn what applications can open and convert it.