Opening STL Files

The STL file type is primarily associated with SolidWorks.

STL	File extension: STL
	File type:	3D model

What is an STL file?

STL files mostly belong to SolidWorks by Dassault. STL filename extension is associated with files containing the surface and geometry of a 3-dimensional object or model. STL files typically contain unprocessed, triangulated surface units and vertices of a 3D model created using Sterolithography 3D design technology which is supported by most CAD software (e.g. AutoCAD, Blender) and 3D printers. The contents of STL files may be stored as ASCII text or in binary format (for larger files). Such STL files are associated with the Standard Tesselation Language format. STL filename extension is also associated with the native movie subtitle format used to save subtitles created with EZTitles subtitle generation software. Other subtitle generation programs also use STL format. Visual C++, a C++ programming language IDE stores its standard template library in an STL file. ROSE Online, an MMORPG game stores some data in STL files. Super Tux, a 2D video game stores game level data in STL files.

How to open STL files

You need a suitable software like SolidWorks to open an STL file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your STL file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a STL file directly in the browser:. Just drag the file onto this browser window and drop it.

Online STL File Viewer

Choose your .stl file to view

or drag and drop it here

Online File Viewer

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How to convert STL files to OBJ, STL, PLY, 3DS, FBX, STP, ...

If you want to convert or edit an STL file, you can use our free Online STL File Converter (powered by Convert.Guru):

Just click the "Choose your .stl file to view" button on this page.
Your STL file will then be displayed in the browser.
Now click on "Save as..." at the top of the page.
Then select the 3D format (e.g. STL, OBJ, 3DS, X, X3D, STP, PLY, ...) you want.
Your file will be converted and downloaded.

Programs that open and convert STL files:

SolidWorks by Dassault
See the previous paragraphs to learn more about the main application. STL files are often referred to as SolidWorks 3d images because this type of file is primarily created or used by this software.
Alibre (3D model) by Alibre
Alibre is a computer aided design and computer aided manufacturing software. It features a variety of parametric design tools suited for automotive product design, industrial design, 3D printing, and much more. Models created with Alibre may be stored or exported in various formats such as STL. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
AutoCAD (3D model) by Autodesk
AutoCAD is a cross-platform computer-aided design software that is mainly used to create 2D/3D architectural designs and construction plans. The program can also create simulations and animation from 3D models. Models created with AutoCAD may be stored as binary or ASCII data in STL files. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
Blender (3D model) by Blender
Blender is a free and open-source 3D modeling software with an extensive toolkit for creating 3D animation, models, and art. 3D meshes and models exported from Blender may be stored in STL files. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
CAD file by CST CAD Navigator
Enables to open and convert different 2D/3D files, get their dimensions and create section views. The software is compatible with Windows, macOS, and Linux.
CaSat (teletext) by SoftNI
CaSat is a multi-channel, multi-platform, modular subtitling program for multilingual cable/satellite transmission. It provides subtitles in most European, Asian, African, and Middle Eastern languages. Teletext generated by CaSat are stored in STL files. This file format is classified as Video.
ClarisWorks (data) by Apple
ClarisWorks was an office productivity software suite for classic IIGS, Macintosh, and Windows computers. The software suite comprised a word processor, spreadsheet program, and a database management system. Some data used by ClarisWorks were saved in STL files. This program has been discontinued. This file format is classified as Data.
CorelDRAW (stylesheet) by Corel
CorelDRAW is a vector graphics editing software for Windows and Mac operating systems. MicroGrafx Designer, a CAM/CAE software that was integrated into CorelDRAW stored its stylesheet in an STL file. This file cannot be opened with CorelDRAW. This file format is classified as Vector Image. Related links: Looking for Micrografx Designer?
Creo (3D model) by PTC
Creo is a 3D product design and manufacturing software mainly used to design and simulate automobile parts, factory machinery etc. 3D models, meshes, and/or objects created with Creo may be stored or exported in STL format which is also supported by most 3D design applications and printers. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
EZTitles (subtitle) by EZTitles
EZTitles is a professional movie, TV, and streaming subtitling solution. It's native subtitle format is STL. The contents of these subtitles are written in XML-like syntax. This file format is classified as Video.
Fireworks (style library) by Adobe
Fireworks is a discontinued image editor used to create or edit vector and bitmap images for websites and native applications. The style library of this program was stored in an STL file. This file format is classified as Vector Image.
IIS (certificate trust list) by Microsoft
IIS, short for Internet Information Services is a highly scalable web server for hosting web applications, streaming services, and other applications on Windows server platforms. The Certificate Trust List (list of trusted certificates) used by IIS is saved in an STL file. This file format is classified as Developer. Related links: How to Create a Certificate Trust List in Windows Server 2008 R2 for Use with Unified Access Gateway
MeshLab (3D model) by ISTI - CNR
MeshLab is a cross-platform computer-aided design software for managing and processing large, unstructured 3D meshes. 3D mesh data and models stored in STL format may be imported and edited with MeshLab. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
Rhinoceros 3D (3D model) by Robert McNeel & Associates
Rhinoceros 3D is a 3D modeling software for Windows and Mac operating system. This program is mainly used for design operations such as rapid prototyping, CAM, product design, automotive design, and 3D printing. 3D models created with Rhonoceros 3D may be saved in STL files. This file format is classified as 3D Image. Related links: STL (file format), Stereolithography
SPEFO (stellar spectra analysis data) by Astronomical Institute of the Czech Academy of Sciences
SPEFO is a lightweight program used to perform stellar spectra data analysis. The program is written in Pascal and it ran on MS-DOS computers. The STL file used by SPEFO contains a stellar spectra analysis. This file format is classified as Data.
Visual C++ (C++ standard template library) by Microsoft
Visual C++ is a software package that provides the run-time packages used to run applications written in C++ programming language using Visual Studio. The C++ standard template library used by the program is stored in an STL file. This file format is classified as Developer.
Win2020 (screen subtitle) by Screen Subtitling Systems
Win2020 is a discontinued program used to create screen, television, and film subtitles on Windows 95 and 98. Subtitles created with Win2020 were stored in STL files. This file format is classified as Video.

STL file format:

The file format, which is the arrangement and type of data in a file, determines which program can open the file. The file format can be deduced from the file extension and the signature. However, different programs can use the same file extension, and file extensions can be assigned incorrectly. So a detailed analysis of a file is vital in order to determine the format and the associated program. Our evaluation of the STL files looks like this:

STL is one of the most common file extensions and covers different formats for different programs. However, the following two file formats are common:

25% of all STL files are STereoLithography files. STL files are between 14 KB and 8 MB in size. The file type was developed only in the last few years. The keywords solid, facet normal, outer loop and vertex are typical for these files. These files can be linked to base, dbenchy, support, insert, conv, bottom, model, plate, grip and left.
20% of all STL files belong to ATF STereoLithography. The content consists of illegible binary data, which can only be read and interpreted by the associated programs. The files are 43 KB to 17 MB in size, with a median of 780 KB. Several words can almost always be found in the files, e.g. STLB and COLOR. Such files are related to case, assist, holder, image, small, tostl and body.

All the rest of the STL files (55%) have different formats, often e.g. Blender exported STereoLithography, Rhinoceros STereoLithography, FreeCAD STereoLithography, Certificate Trust List, ArtCAM STereoLithography, SketchUp STereoLithography, AutoCAD STereoLithography, Source, STL, Created and Made. Tagged as familiare, uploads, driver, export, front, right, upper, mask or ring. If you want to find out which format your STL file belongs to, just click on the button "Choose your .stl file to view".

Technical Data for STL File Extension

File classification:

3D Image

Related files:

sti, slt, gx, ctl, 3d, step, gcode, obj, x3g, zip, glb, stf, sdl, stp, sldprt, 3mf, sli, stg, f3d, gco, smg, prt

Mime type:

application/vnd.ms-pki.stl, application/sla, model/stl

The following listing is compiled from the database produced by the 'Associate This!' program, selected data from the main FILExt database and file extension information submitted by users.

ProgramID: STLFile, FileType: Certificate Trust List, AppName: Crypto Shell Extensions
EXEFile: cryptext.dll

ProgramID: FireworksStyleLibrary
EXEFile: %ProgramFiles%\Macromedia\Fireworks MX 2004\Fireworks.exe %1

ProgramID: FireworksStyleLibrary
EXEFile: %ProgramFiles%\Macromedia\Fireworks MX\Fireworks.exe %1

ProgramID: FireworksStyleLibrary
EXEFile: D:\Macromedia\Fireworks MX 2004\Fireworks.exe %1

ProgramID: FireworksStyleLibrary
EXEFile: D:\Macromedia\Fireworks MX\Fireworks.exe %1

ProgramID: OrCADPSpiceADStim10.0.0
EXEFile: C:\OrCAD\OrCAD_10.0_Demo\tools\PSpice\stmed.exe %1

ProgramID: STLFile
EXEFile: %SystemRoot%\system32\rundll32.exe cryptext.dll,CryptExtOpenCTL %1

ProgramID: STLFile
EXEFile: rundll32.exe cryptext.dll,CryptExtOpenCTL %1

ProgramID: FireworksStyleLibrary
EXEFile: F:\Fireworks MX 2004\Fireworks.exe %1

ProgramID: logview.1
EXEFile: %ProgramFiles%\Microsoft Speech SDK\tel\logview.exe %1

ProgramID: STLFile
EXEFile: rundll32.exe %SystemRoot%\ServicePackFiles\i386\cryptext.dll,CryptExtOpenCTL %1

ProgramID: FireworksStyleLibrary
EXEFile: %ProgramFiles%\Macromedia\Fireworks 3\Fireworks 3.exe %1

ProgramID: FireworksStyleLibrary
EXEFile: %ProgramFiles%\Macromedia\Fireworks 4\Fireworks 4.exe %1

ProgramID: OrCADPSpiceADStim10.5.0
EXEFile: C:\OrCAD\OrCAD_10.5_Demo\tools\PSpice\stmed.exe %1

ProgramID: FireworksStyleLibrary
EXEFile: %ProgramFiles%\Macromedia\Fireworks 8\Fireworks.exe

ProgramID: stlfile
EXEFile: %ProgramFiles%\formZ\formZ RadioZity MP v4.1.0\formZ RadioZity.exe

ProgramID: stlfile
EXEFile: %ProgramFiles%\formZ\formZ RadioZity v4.1.0\formZ RadioZity.exe

ProgramID: Fireworks.stl
EXEFile: %ProgramFiles%\Adobe\Adobe Fireworks CS3\Fireworks.exe

Show all 18 listings To Top

an stl 3D model is a special file format by Dassault and should only be edited and saved with the appropriate software.

How to solve problems with STL files

Associate the STL file extension with the correct application.
Update your software that should actually open 3d models. Because only the current version supports the latest STL file format. Search, therefore, e.g. on the Dassault manufacturer website after an available SolidWorks update.
To make sure that your STL file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .STL file online - secure, fast, and no downloads needed.