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Drop OST File here
OST to PST
Convert Outlook OST files to PST format online and restore access to emails, contacts, calendars, tasks, and attachments without installing Microsoft Outlook or connecting to Exchange Server.
Convert OST to PST
Our online OST to PST conversion service helps recover mailbox data from offline Outlook data files and convert it into a standard PST file on a secure remote server. This is useful when the original Exchange Server profile is damaged, Outlook cannot open the mailbox, or access to the email account is no longer available because of forgotten credentials, account restrictions, or server-side limitations.
Upload your OST file, start the conversion process, and receive a PST file that can be opened in Microsoft Outlook. The service is designed for users who need to safely extract data from their own OST files without manually repairing Exchange profiles or rebuilding the original mail connection.
Step 1
Select OST file
Step 2
Converting
Step 3
Download PST file
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The program has no restrictions on the number and size of files
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How to convert OST to PST online
A step-by-step description of the online conversion of OST files of any version to Microsoft Outlook PST files:
- Select an OST file on your hard drive here https://www.osttopst.online
- Wait for the file to be uploaded to the service and the OST to PST conversion process to be over
- Download the converted PST file with your data
How to convert an OST file to a PST file online
This online converter of OST files to PST files makes it possible to transfer data from one format to another using any device and any operating system (Windows, Android, iOS, Mac OS, etc).
Our OST to PST online conversion service does not require access to Exchange Server, Windows Domain Controller or Microsoft Outlook. All you need to do is upload your OST file to the server. Next, you will receive a link to download the converted PST file containing all of the data from the original OST file, including: e-mails, contacts, appointments, reminders, tasks, notes, calendars, journals, attachments, etc.
The .ost to .pst converter service allows you to convert the following types of OST files:
- OST files in Unicode format (Microsoft Outlook version 2007 or later)
- OST files in ANSI format (Microsoft Outlook versions 97-2003 that are more than 2GB in size)
- OST files created using all versions of Microsoft Exchange Server
- Encrypted OST files that use any type of encryption
- Password-protected OST files
- OST files created with 32-bit and 64-bit versions of Microsoft Outlook
- OST files created of Outlook for Microsoft 365
The benefits of the online OST to PST file conversion service
The .ost to .pst converter service works on any device that is connected to the Internet
Does not require you to have Microsoft Windows installed
Does not require authentication by Windows Domain Controller
Does not require access to a Microsoft Exchange Server
Does not require you to have Microsoft Outlook installed on your device
Notes: If unable to convert OST file online, then you can repair OST file using online Outlook recovery service. This is an online version of the famous Recovery Toolbox for Outlook program, which repairs all types of corrupted OST files and recovers all versions of Microsoft Outlook data files. The service also fixes complex errors with faulty Microsoft Outlook data files such as 0x8004010F: Outlook data file cannot be accessed. You will also receive a PST file with your data, but it will require a bit more time.
The service works with almost all types of devices and operating systems. https://outlook.recoverytoolbox.com/online/
How to import OST file in Outlook
Microsoft Outlook has no function for importing OST files. This means it's necessary to use tools or services from off-site software suppliers. Import of OST in Outlook results in conversion of OST to PST and opening of PST file with converted data in Microsoft Outlook. A detailed instruction is provided below:
- To convert OST to PST with the help of online-service and tools from the website https://www.osttopst.online
- To open the converted PST files in Outlook menu: File | Open&Export | Open Outlook Data File
Notes for the Microsoft OST 2 PST converter service:
- The size of the converted PST file may be considerably smaller than the size of the original OST file.
- The converted PST file will be saved in Unicode format as a *.PST file that is used as the default file format in Microsoft Outlook 2007 or later. This format allows you to store more than 2GB of data in a single file.
- The files are stored for 10 days starting from the time that the source file is uploaded to the server;
- The converted PST file will not be encrypted or password-protected.
Price
The cost to convert an OST file to PST online is as follows:
$ 10 - per - 1 Gb
FAQ
How to convert OST to PST without Microsoft Outlook installed on the computer?
You can convert OST to PST without having the Microsoft Outlook application installed by using this online conversion service. The web-based engine operates independently of Outlook MAPI (Messaging Application Programming Interface) components, allowing the system to extract mailbox folders, email messages, attachments, and calendar data directly from the raw binary structure of the orphaned offline storage file (.ost) and rebuild them into a standalone personal storage file (.pst) on the server side.
Can I convert a large OST file to PST format without losing emails or attachments?
Yes, you can convert large OST files to PST format without any data loss or truncation of email attachments. The processing engine handles offline folder storage files exceeding 25GB or 50GB by parsing the internal Exchange database tables sequentially. This methodology ensures that the output Unicode PST file perfectly matches the original folder hierarchy, preserves inline images, embeds attachments, and retains metadata headers such as To, CC, BCC, and Sent Date without hitting the Outlook file size limit errors.
How to fix and convert a corrupted or orphaned OST file when Exchange Server is offline?
To convert a corrupted or orphaned OST file when the Microsoft Exchange Server or Domain Controller is permanently offline, you simply need to upload the cached file to this converter. The utility does not require an active connection to the Exchange server, Windows Active Directory, or the original Outlook user profile. It treats the offline cache file as an independent data source, bypassing synchronization errors and reconstructing the internal database structures into a healthy Microsoft Outlook PST file.
Will the converter process password-protected or encrypted OST files without the original password?
Yes, this online tool can read and convert password-protected or highly encrypted OST files without requiring the user to enter the original Outlook backup password. The decryption algorithm automatically strips the localized password flags and security locks from the Exchange offline folder storage headers during the extraction phase, mapping the recovered mailboxes into a clean, unencrypted personal storage database (.pst) that can be opened instantly in any version of Microsoft Outlook.
How to convert an IMAP or Office 365 OST cache file to PST format without a Microsoft account?
You can convert an Outlook IMAP cache or Office 365 .ost file into a standard PST database without logging into a Microsoft Account or Azure Active Directory. The converter decodes the localized OST structure generated by Outlook 365, Outlook 2021, 2019, or 2016. It extracts all cached IMAP folders, contacts, tasks, and journals directly from the local file system backup, removing any dependency on cloud synchronization or active user subscriptions.
Help
The process of converting OST files to PST files using the online service consists of several steps:
Description of the conversion steps:
- Uploading the OST file to the service
On the service home page you must select your source OST file and fill e-mail address field.
You will be sent a notification by e-mail when the conversion process is complete or if the conversion is interrupted with the URL of the page where you can continue the conversion.
When all the fields are filled in, you will be able to press the Next Step button. The OST file will now be uploaded to the service. The service will now display the status of the upload and conversion process.
- Converting data into a PST file
Once the OST file is uploaded to the server, special software that was developed by our engineers will analyze the contents of the OST file and transfer the data to a new PST file.
Depending on how busy the server is and the size of the original OST file, the conversion process can take a significant amount of time.
Notes: The size of the new PST file may be considerably smaller than the size of the original OST file. This difference is due to the way that Exchange Server and Microsoft Outlook store data in OST files.
- Preview of conversion results
When the file has been successfully converted, the user will be notified about the size of the original OST file and the converted PST file. In addition, the user will be able to quickly review the restored data in the preview.
- Payment for the OST to PST file conversion service
We accept payment for the OST to PST conversion service via PayPal and FastSpring. By clicking the Pay button you will be redirected to either the PayPal of FastSpring website, where you can pay using the payment method that is most convenient for you.
After payment is confirmed, the user will be given a link to the converted PST file. In addition, an e-mail will be sent to the user's specified address with a link to the converted file.
- Downloading the PST file from the service
You have 10 days to download the converted PST file at the specified URL. This period is measured from the time when the original source file was uploaded to the service.
How to convert an OST file to PST file online
This online service allows you to perform an OST2PST conversion using any device (Windows, Android, iOS and other). You do not have to have Microsoft Outlook, Exchange Server or Windows Domain Controller installed on your device. All you need to do is upload your OST file to the service in the same way that you would upload files to a cloud storage service (such as iCloud, Dropbox, Google Drive, OneDrive, etc.) and wait for the service to automatically convert all the files and provide you with a converted PST file to download.
How to convert .ost to .pst file online
Steps for obtaining a PST file from an OST file:
- Uploading your OST file to the server
You can upload the OST file to the server on the service's home page. To upload a file: Select the file on disk
- Preview
You will be given information about the following when the conversion is complete:
- The size of the original OST file
- The size of the converted PST file
- The structure of folders with data in the PST file
You can then click the Next step button.
- Payment
In order to download your converted PST file, you will need to pay using PayPal, which allows you to use a credit card as well as other payment methods.
- Downloading the PST file
Once payment is complete, the user will see a Download button to obtain the converted PST file.
Notes:
- The size of the resulting PST file may differ significantly from the size of the original OST file. The difference in file sizes can be explained by the different storage, archiving, and processing methods that are used by Microsoft Exchange Server and Microsoft Outlook when working with OST files.
- The converted PST file will be in Unicode format (which has been used since Microsoft Outlook 2007 to store more than 2GB of data in a single file).
- The service can read and convert OST files that are password protected
- The service can read and convert OST files that are encrypted
- The converted PST file will not be encrypted or password-protected, however.
- The original OST file and the converted PST file will be kept on the server for 10 days from the date that the original file was uploaded to the server
Secure OST to PST Conversion Technology
Our online converter prioritizes user data privacy, executing 100% of the mailbox analysis process directly within your web browser environment and within an isolated area of a remote server, free from external access. All temporary memory structures and output streams of the Personal Storage Table (.pst) file are secured using AES-256 cryptographic encryption standards, while the entire web session is securely isolated via the SSL/TLS 1.3 protected connection protocol. All data uploaded to the remote server is automatically deleted following conversion.
Data Protection & Encryption Architecture
- Processing Mode
- Fully isolated client data recovery on a remote server. Data deletion after conversion.
- Encryption Standard
- Internal data structures are protected with AES-256 cipher block chaining.
- Transport Security
- Enforced HTTPS with SSL/TLS 1.3 encryption across all active browser sessions.
Resources
- Microsoft Outlook: Official Microsoft Outlook Page
- Microsoft Outlook on Wiki
- Microsoft Exchange Server on Wiki
- Path of OST and PST files of Microsoft Outlook in Windows
- IMAP on Wiki
- Data Convertion on Wiki
Victor G. Bobrov, Senior Software Engineer.
MCSD, MCDBA
Specialist in Microsoft Outlook, Exchange Server, and OST/PST file structures. Expert in OST file conversion with over 20 years of experience and expertise.
Customer reviews from Trustpilot
Customer's reviews and ratings
Software was easy to use, it extracted 95% of required data from the OST file. I found out after purchasing, it was unable to recover group contacts. I had no way to test this with the demo. The support team indicated that Microsoft blocks access to exporting group contacts into a PST file. I tested this theory by using another product, which had no issues recovering group contacts to a PST file. So please be aware of this limitation in the software.
Otherwise, software works as expected.
Conversion: OST 20GB to PST 23GB. Windows 11 64-bit Outlook 64-bit, everything worked perfectly. Took about 90 minutes.
JCB 08-20-2025Nice
Sakib 05-18-2025Excellent tool for converting email files.
matsanti 04-15-2025Very good service. Reasonable pricing if you have one or two .ost files to convert.
Adrian 03-16-2025The Convert worked smoothly and did a good job.
What bothered me was that the information that the service was chargeable and the amount of the costs was only provided very late. Of course it would have been possible to cancel at this point, but the data had already been uploaded. I suspect that the user guidance is intended to be this way in order to generate sales.
If I had known this beforehand, I might have looked for another service provider.
Using the online version to see how it goes
Hermes 02-19-2025Even as someone who doesn't know anything about computers, I was able to do it. Congratulations
Günter 01-19-2025I made a mistake when saving an archive in Outlook. Unfortunately, restoring the archive with important emails from the .OST file was no longer possible using the M365 tools because the computer had been changed in the meantime. With the tool, I was able to convert the OST into a .pst file very quickly and without any problems, and thus integrate the archive into M365 (Outlook Classic) without any problems. The price of around €20 was worth it! Great tool. I would use it again.
Rüdiger K. 11-28-2024Excellent
Akhilesh 11-19-2024necessary tool
Gregorio 10-26-2024excellent
prueva 09-18-2024This service helped to migrate from IMAP to POP3.
All .OST files was converted to .PST.
Accounts changed in Outlook from IMAP -> POP3 with saving emails into new .PST files.
Thanks!
Friends, great service, I recommend it to everyone!
Дима 09-27-2023very good service, helped me completely, thank you
Ostin 09-27-2023The ost.file I want to convert to a pst.file is not read in via the conversion mode !
The recovery mode of the same file has worked !
Hello guys!
Great service, congrats!
Goord service
Gabilon 01-25-2023Universal service-tool. They helped me but not fully: part messages didn't uploaded from Gmail to .OST file.
skyw 01-24-2023works fine
mr mike 11-12-2021To recommend
Ferdinand 11-08-2021everything's OK
Hartmut 11-07-2021Top
SK 10-28-2021Greate!
Ermanno 10-15-2021super
jeng 09-07-2021allgood
mohsin 09-03-2021Great service, thank you so much
Rola 08-31-2021it's beautiful
sergio 07-12-2021good and easy application
Mahi 05-13-2021The perfect way to convert OST files. The web interface is very simple and easy to use. Could keep an archive of my emails by converting from .ost to. pst in the online version. This tool works great.
Boris 04-21-2021The best plugin for converting OST to PST, this guys save me!
Shaka 04-12-2021Excellent and convenient service, my OST email was converted to PST losslessly.
Ramiro Finley 04-05-2021Great online service - I received my converted file within minutes - thanks very much
Kirsten 03-20-2021After conversion, letters can be saved in the Inbox folder or in other folders. As it was with me, I was even scared that they would not be returned. They turned out to be in the lowest folder that opens.
Juliana Blankenship 03-15-2021I am always reluctant to use the program on the Internet. But this converter seemed reliable to me. And it turned out to work great, very professional, even a neat texture!
C.Verbeek 03-05-2021Good program
Daniel 02-16-2021Works as advertized and did a good job! Worth its money more than average!
lucsch 02-16-2021An excellent convertion tool .ost to .pst, no losses were noticed during the moving of data.
Radiant 02-15-2021Great tool
Hugi 02-11-2021Could save my mails archive by converting from .ost to . pst in the online Version. Outlook had synchronization issues with the ost file! Thanks this Tool works great!
Mohammad 02-04-2021The program restored all messages and contacts on Outlook 2007 in excellent quality. I do not regret it, I recommend it.
Ashley 02-04-2021Works well and quickly. I can import all my Exchange mail into regular mail. Super!
Qanuk 01-23-2021Could save my mails archive by converting from .ost to . pst in the online Version. Outlook had synchronization issues with the ost file! Thanks this Tool works great!
Marc 01-21-2021Good!
QA 01-10-2021Beautiful
ahemltmw 01-06-2021Good app
Abhishek Ranjan 01-04-2021Great service
James Bond 01-01-2021He can handle the task. Good even with an introductory explanation of PST and OST files. It is worth explaining the text that the service is worth it.
Adee 12-30-2020It is very nice, good health.
selin 12-27-2020By clicking Download or Сonvert, you agree to the Terms of Service and EULA.
Clear. High-quality. Professional.
Alex 10-17-2025Everything that was stated was 100% received.
+ prompt and intelligent support.
5 out of 5...would give more if possible.