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OST to PST converter online

Fast and easy to use OST to PST converter app converts files with size up to 100 Megabytes

Upload OST file by either:

  • Dragging it on this area
  • Clicking on the button below to browse for a file

OST and PST formats are very close to each other. For some versions we only change few file properties and the file is ready to use as a PST storage. But newer files need more tricks to do. Usually we create new PST files from scratch and copy all the contents of the OST file to this new personal storage. Anyway, all this things are happening under the hood and you don't need to know anything about it. Just upload your OST file and get the PST file when it is ready.

We use commercial software to convert OST to PST. This software has a long history of development. It has a very good level of OST and PST formats support. It is used in lots of enterprise projects. And we are happy to give you an opportunity to use some functions for free.


Why OST to PST online?

Big files

Convert OST files up to 100 MB.

Different formats

Different OST versions supported.

Convenient download

We use dedicated file storage for faster downloads.

Ratings and reviews

Ilya V.
March 1, 2024
This is so easy to use and free! Well done and thank you.
Tomas A.
December 13, 2023
Great converter. Will forward it to various friends. Super!!!

Frequently asked questions

OST to PST converter online FAQ

Is it safe to convert OST to PST online?

As long as you don't give the link to the converted file to anyone, it is safe. We don't store your files longer than 24 hours and generate a unique link for download.

How to convert OST to PST?

Just upload your OST file and wait for the conversion to complete. Then download the PST file.

How to convert OST file bigger than 100 MB?

Right now we don't support files bigger than 100 MB. But we are working on it. Perhaps we will add this feature to paid version. Stay tuned.

The Unresolvable Problem of the Online OST to PST Converter

The main problem with the online OST to PST converter is the size of the files. Typically, this feature is needed when there is a large OST file. People want to migrate their entire email archive from one place to another. These files usually range from 3-5 gigabytes in size. We cannot store such large files on our cloud, as we have many users simultaneously. Additionally, it is a significant overhead when users have to upload such large files to our storage and then download the result. It would be much more convenient to convert the files on the client side. However, all the offline libraries we know of that could do this are proprietary and very expensive.

We've conducted extensive research to resolve this issue. We've tried to support large files online and found some offline tools. We even attempted to move our algorithm to web assembly. But, unfortunately, we have not yet found a free solution to this problem. So, we decided to limit the file size to 100 MB. We hope our app will be useful for users who, for some reason, need to convert small OST files. Our colleagues, who are working on the converter library development, continue to try to move part of the features to web assembly, to make it possible to use without uploading large files to the server. Perhaps, one day, this issue will be resolved.

By the way, you can use MS Outlook to save your OST file in PST format. The problem is, you cannot just use the OST file as an input. You need to have the original mailbox. If you have it, you can just export the mailbox to PST. Outlook has the Import and Export Wizard for this. So, make sure, that you have exported your data to a PST file before you lost access to the mailbox. We hope that in future you will be able to use open-source file formats to store your email data, such as MBOX or EML. Those formats are much easier to work with. Even if you lost access to the application that created the file, you can always find a way to read the data.