Free online viewer
Open Winmail.dat (TNEF) Files Online
Read your Outlook message free in your browser. No account needed; your file is never uploaded. Attachment viewing and saving need a subscription or credits in the iOS app.
How to open your file
- Choose your file above. Select or drop a winmail.dat file saved on your device.
- Read the message privately in your browser.
- Need the attachments? Open the original file in Winmail File Viewer for iPhone or iPad.
Which .dat Files Can This Viewer Open?
This viewer opens Outlook winmail.dat files in Microsoft’s TNEF format. Game data, databases, unrelated media, and damaged or encrypted files use different formats and will not open.
Learn about winmail.dat and TNEF →Winmail.dat Reader Online FAQ
Does the online reader upload my file?
No. Decoding runs in your browser with WebAssembly, so the file stays on your device.
Can it extract winmail.dat attachments?
The web viewer shows the message and a locked attachment list. Open the original file in the iOS app with a subscription or credits to view and save the attachments.
Which .dat files does it open?
Outlook TNEF containers only — not game, database, or media files that happen to use the .dat extension.