A file you cannot open is usually one made by a program you do not have: an Outlook mailbox, an Access database, an AutoCAD drawing, a Pages document from a Mac, a scan from a hospital. The tools on this site open many of those in the browser, without the program and without uploading the file. This page finds the right one from the file's extension, the letters after the last dot in its name.
- Is my file uploaded when I drop it here?
- No. This page reads the file's name to find its extension, and nothing else: the contents are not opened, and nothing is sent anywhere. The tool you go on to says above its title where it does its work, and nearly all of them work entirely in your browser.
- Why do I have to choose the file again in the tool?
- Each tool opens files itself, and this page deliberately never opens yours. Choosing it a second time is the cost of this page knowing nothing but the name.
- How do I see a file's extension?
- Windows hides them by default: in File Explorer, open View, then Show, and tick File name extensions. On a Mac, open Finder, then Settings, then Advanced, and tick Show all filename extensions.
- What if nothing here opens my file?
- Use the link that appears to say what the file is and where it came from. File types people cannot open are exactly what new tools here are chosen from.