OST SaverConvert, merge and recover OST and PST files
Right in your browser: turn an .ost into a PST that Outlook opens in two clicks, merge several mailboxes into one file, save individual emails and rescue whatever is still readable from damaged files. Nothing to install: your file never leaves your computer.
Free to open and read everything. The free version converts the first 25 messages of each folder, so you can check the result in Outlook before you pay.
Open in Outlook
Your .ost becomes a PST that opens in any Outlook, without the original account.
- Open the .ost
- Convert
- File › Open in Outlook
Merge mailboxes
Several .ost and .pst files in one. Matching folders are combined and duplicates are kept once.
- Open the first
- Add the others
- Convert
Save emails
One message or a whole folder as .eml files, which open in any email program.
- Open the folder
- Save message or folder
Recover a damaged file
Rebuilds the indexes and saves whatever is readable, including messages outside any folder.
- Open the file
- Recovery mode
- Convert
Three steps, nothing to install
The program is loaded by your browser and runs on your computer, like an app. Your emails never pass through a server.
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Open the file
Drag the .ost or .pst onto the page. Close Outlook first, because it locks the file while it is running.
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Check the contents
Browse the folders, read messages and download attachments. All of this is free and unlimited.
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Convert and save
Build the PST and choose where to save it. In Outlook, use File, Open & Export, Open Outlook Data File.
What OST Saver does
Read before you convert
See folders, messages, attachments and inline images exactly as they are in the file. Use it to find a specific message or to check that the file is complete, without converting anything.
Merge several mailboxes into one PST
Combine an OST with old PSTs, or several accounts. Equivalent folders are merged, even when their names are in different languages, and duplicate messages are kept only once.
Save individual emails
Save one message, or a whole folder with its subfolders, as .eml files with attachments and images. They open in Outlook, Thunderbird, Apple Mail and any other email program, and make a handy backup of important messages.
Recover damaged files
When the file is corrupted and Outlook won't open it, recovery mode reads the whole file, rebuilds the indexes and copies everything still readable into a new PST. Messages that lost their folder go to "Recovered items", and damaged attachments are left out without dropping the message.
Split large files
Pick a maximum size and the result comes out in parts, each with the same folder tree. Useful for storage media, sending, or the size limits of older Outlook versions.
Your emails stay on your computer
Online converters ask you to upload the whole file to a server. Desktop programs ask for full access to your computer. OST Saver does the work inside the browser, sandboxed, and the page is blocked from sending data out.
| Online converter | Desktop program | OST Saver | |
|---|---|---|---|
| Uploads your file | Yes | No | No |
| Needs installing | No | Yes | No |
| Large files | Limited by upload | Yes | Yes |
| Read before paying | Sometimes | Sometimes | Yes, everything |
Pricing
Opening and reading is always free. Pay only to convert everything.
Free
- Open and read everything
- Converts 25 messages per folder
- Saves individual messages as .eml
Per mailbox
- Full conversion
- Convert again for 30 days
- Card, PayPal, Apple Pay
Prices in US dollars; sales tax or VAT is added at checkout where it applies. Payment is processed by Paddle, our reseller. The license is issued right after payment. The per-mailbox purchase is made inside the converter, after you open the file. Already bought? Recover your license.
Guides
Answers for the most common situations with Outlook data files.
How to open an OST file without Outlook
Why Outlook rejects a standalone .ost and how to read the messages.
Emails from a deleted account or former employee
When the account is gone and only the .ost is left on the computer.
How to open a PST file in Outlook
The steps in classic and new Outlook, and what to do if it refuses the file.
Corrupted OST or PST file
What recovery can save, what it cannot, and how it compares with scanpst.
Move Outlook emails to a new computer
Which file to copy for each account type, and when you need to convert.
Frequently asked questions
Is my file uploaded to a server?
No. The converter runs inside your browser, on your computer. The file is read and the PST is written locally; no email ever leaves your machine. The page only loads the program itself and is blocked from sending data anywhere else.
Why won't Outlook open my .ost file?
An OST is the offline copy of an Exchange, Microsoft 365 or IMAP account and is tied to the profile that created it. Outlook only opens standalone data files in PST format, so the OST has to be converted.
Are calendar, contacts and attachments converted too?
Yes. Every folder is copied with its messages, attachments, attached messages, calendar items, contacts, tasks and notes, plus the folder settings.
What is the maximum file size?
There is no fixed limit; 6 GB files have been converted. The practical limit is free disk space: keep at least twice the size of the file free.
Do I need to install anything?
No. An up-to-date browser is all you need. Chrome and Edge let you choose the folder where the PST is saved; Firefox puts it in your Downloads folder.
Can it repair a corrupted PST or OST file?
In most cases, yes. Recovery mode reads the whole file, rebuilds the damaged indexes and copies everything still readable into a new, healthy PST. Data that was overwritten or wiped on disk cannot come back; the report shows how many items could not be saved.
How do I save individual emails?
Open the folder, select the message and use "Save message (.eml)", or "Save folder (.eml)" to save the folder and its subfolders in a .zip. .eml files open in any email program.
How does the free version work?
You can open and read the whole file with no limit. The conversion includes the first 25 messages of each folder, enough to open the PST in Outlook and check folders, attachments and formatting before you buy.
How do I pay, and is VAT included?
Checkout is handled by Paddle, our reseller, with card, PayPal, Apple Pay or Google Pay. Paddle adds sales tax or VAT where it applies and sends you the receipt. The license arrives right after payment.