OST → PST · ALPHA
Convert an Outlook OST file to PST, on this computer.
The converter runs inside this browser tab. Your mailbox is read from disk, rebuilt as a Unicode PST, checked against the original, and saved back to disk. No part of it is sent anywhere.
Drop an .ost file here
Outlook 2013, 2016, 2019, 2021 and Microsoft 365 (Unicode OST)
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- Where is my OST? Usually %LOCALAPPDATA%\Microsoft\Outlook. Close Outlook before copying it.
- Keep the original. The OST is only read, never changed — but keep a copy until you have opened the PST.
- What comes across: folders, mail, attachments, contacts, calendar and tasks that were synced into this OST.
- File
- Size
- Format
- Contents
Converting
0%
Keep this tab open. Large mailboxes take a few minutes; the work happens on your own CPU and disk.
PST ready
Open it in Outlook with File → Open & Export → Open Outlook Data File. This is an alpha release: keep your original OST until you have checked the PST.
No PST was produced
The conversion engine is Rust compiled to WebAssembly and runs entirely in this tab. The page loads only its own files; you can go offline once it says Ready.