If you work with 3D CAD files, especially in the realm of product design or manufacturing, you're likely familiar with the STP file format. Viewing these files can be a challenge, especially if you don't have access to expensive 3D CAD software. Fortunately, there are several free online STP file viewer tools that can help you view and collaborate on these files without breaking the bank. Here are some of the best options available:

1. STP Viewer Online: STP Viewer Online is a simple and easy-to-use tool that allows you to upload and view STP files directly in your web browser. It supports a variety of 3D file formats and provides basic viewing and rotation capabilities. This is a great option for quick and easy viewing of STP files without the need for any special software.

2. ShareCAD: ShareCAD is another online CAD file viewer that supports a wide range of file formats, including STP. With ShareCAD, you can upload your STP files and view them in 3D, as well as take measurements and annotate the files. This tool also allows for collaboration, making it a great option for teams working on 3D CAD projects.

3. Autodesk Viewer: Autodesk Viewer is a powerful online tool that allows you to view and collaborate on a variety of 3D file formats, including STP. With Autodesk Viewer, you can not only view the files in 3D, but also take measurements, add markups, and share the files with others. This is a great option for those who need more advanced viewing and collaboration capabilities.

4. Online 3D Viewer: Online 3D Viewer is a versatile tool that supports a wide range of 3D file formats, including STP. It allows you to view your STP files in 3D, as well as take measurements and annotations. This tool also supports virtual reality (VR) viewing, making it a great option for those who want to experience their 3D designs in a more immersive way.

5. Glovius: Glovius is an advanced online CAD viewer that supports STP files, as well as many other 3D file formats. With Glovius, you can view, analyze, and collaborate on your STP files, as well as take measurements and create cross-sections. This tool is more advanced than some of the others on this list, making it a great option for those who need more robust viewing and analysis capabilities.

Whether you're a professional designer, a manufacturer, or simply someone who occasionally works with 3D CAD files, having access to a free online STP file viewer can be incredibly useful. These tools allow you to view and collaborate on STP files without the need for expensive software, making 3D CAD more accessible to a wider audience. Try out one of the options listed above and see which one works best for your needs!