How to Open a .dat File
.dat is not a format. It is a placeholder extension that any program can use for its own data, so two .dat files may have nothing in common. The first step is not opening it but identifying it.
.dat
Why it will not open
- The extension carries no information. Unlike .pdf or .png, .dat makes no promise about the contents, so your operating system has nothing to associate it with.
- Double-clicking cannot work. There is no single application that opens .dat files, because there is no single thing a .dat file is.
- Searching for "dat file opener" leads nowhere for the same reason — a tool that claims to open all .dat files cannot be doing anything meaningful.
How to open it
Identify it first
- 1 Drop the file into the file identifier on this site.
- 2 It reads the first bytes — the signature almost every binary format begins with — and names the actual format regardless of what the file is called.
- 3 From there you either open it here, or you learn which application it belongs to.
Common cases, by where the file came from
- 1 From an email, usually named winmail.dat or ATT00001.dat: this is an Outlook TNEF attachment containing an entire message.
- 2 From a game or an application folder: proprietary save or asset data, readable only by that program. There is generally nothing to be done with it outside the application.
- 3 From a video device, often VIDEO_TS or similar: an MPEG stream that VLC will usually play if you rename it to .mpg.
- 4 From a backup or export: sometimes plain text or CSV underneath. Opening a copy in a text editor is a harmless way to check.
Renaming is safe to try, but rarely the answer
Changing the extension does not alter the contents, so it costs nothing to try on a copy. But it only helps when the file really is a known format wearing the wrong name — it cannot make a proprietary format readable.