Welcome to FileExtension.org, one of the oldest online knowledge bases about file extensions.
In the beginning we focused on information alone: what each file extension is, and which programs can handle a given file. But in the age of AI and instant access to information, that no longer feels like enough.
So we rebuilt the service around tools that open files with different extensions directly. You no longer have to track down the right program and then install it. Now you open your files right here, with dedicated tools. It doesn't get any simpler.
Browse by category
Every format we can open, grouped the way you think about them.
What people are opening
The most-opened file formats on FileExtension.org.
Top this week Trend
- 1.PDFPortable Document Format File▲
- 2.JPGJPEG Image-
- 3.PNGPortable Network Graphic▲
- 4.DOCXMicrosoft Word Open XML Document▼
- 5.XLSXMicrosoft Excel Open XML Spreadsheet▲
- 6.MP4MPEG-4 Video File-
- 7.ZIPZipped File▼
- 8.DOCMicrosoft Word Document▲
- 9.RARWinRAR Compressed Archive-
- 10.GIFGraphical Interchange Format File▲
All-time popular
- 1.PDFPortable Document Format File
- 2.JPGJPEG Image
- 3.PNGPortable Network Graphic
- 4.DOCXMicrosoft Word Open XML Document
- 5.XLSXMicrosoft Excel Open XML Spreadsheet
- 6.MP4MPEG-4 Video File
- 7.ZIPZipped File
- 8.DOCMicrosoft Word Document
- 9.RARWinRAR Compressed Archive
- 10.GIFGraphical Interchange Format File
Trending viewers Database
File extensions A-Z
Pick a letter to browse every format we can open.
How it works
From “what is this file?” to “it’s open” in three steps.
Find it
Search the extension or drop the file. We work out which viewer fits that exact format.
Open it
The right viewer loads instantly - no account, no install needed.
Use it
Read, search, zoom or export, right where you dropped the file.
What is a file extension?
A file extension is the short suffix after the last dot in a file name. It tells your computer, and you, what kind of data the file holds and which program should open it.
Extensions can be wrong, missing or unfamiliar. Look one up above, or drop the file in and we’ll open it with the right viewer.
Are the viewers really free?
Yes. Every viewer on FileExtension.org is free to use, with no trial periods, no watermarks and no account required.
Which file formats are supported?
We can open over a thousand formats: documents, images, archives, spreadsheets, e-books, 3D models, fonts and more. Browse them by category or letter above.
Does it work on my phone?
Yes. Everything runs in a modern browser on Windows, macOS, Linux, Android and iOS.
I can’t find my extension. What now?
Drop the file into the box above. If we don’t have a viewer for it yet, you can send it to us and we’ll add it.