Bulk Convert Multiple OSTs with Zero Disruption on Windows or Mac OS.
*SysInfo OST Converter Pro Fully Secure Download Version.
Explore the significant features of the OST File Converter to simplify email management.
Key scenarios where using this specialized conversion tool is highly beneficial for all.
Transitioning from on-premise Exchange server to M365, Google Workspace, Outlook.com, Yahoo, or other platforms? SysInfo OST File to PST Converter allows you to streamline the data migrations with precision and full data security with zero loss. Validate mailbox content before migration without a parallel Exchange environment, account reactivation, or profile recreation during the entire process.
Unable to access your OST files in Outlook? Account deprovisioned, subscription lapsed, Outlook crashed, or OST becomes orphaned? Get the SysInfo OST File Converter to instantly import OST to Outlook in batches without any intermediary support or checks in between. Open and view your files on the local OS with no server uploads, ensuring full data fidelity and safety, keeping the original OST intact with no alterations.
Convert OST to DOC, PDF, JSON, MD, etc. formats as required to access across platforms or maintain communication records and evidence for legal compliance. Use date range filtering and other advanced filters to set data as per needs and verify the preservation of the forensic chain of custody of your data through the preview panel on the system, ensuring nothing leaves the compliance limits.
Processing 300 decommissioned mailboxes or accessing a 5-year-old backup, this tool handles it all for everyone.
IT Admins & Enterprise Teams
Bulk convert multiple orphaned OSTs at scale during Exchange decommission, employee offboarding, or system refreshes with advanced filtering.
Forensic Investigators & Org. Analysts
Deeply analyze OST in the 10-tab preview pane and convert OST to CSV/PDF formats for business intelligence & structured reports.
Individual Home and SMB Users
Restore personal email historical archives from old OST backups without Outlook, Exchange, or M365 in multiple formats, or move OST file to another drive with preserved data fidelity.
Legal, Healthcare, & Finance Experts
Extract OST archives and email evidence with full metadata and header integrity for GDPA and sector-specific compliance and industry standards, with full processing log reports.
Streamline batch conversion of multiple OSTs to cloud and local destinations with one licence.
| File Formats | PST, MBOX, EML, MSG, DOCX, PNG, ICS, VCF, PDF, CSV, MD, JSON, and Mozilla Thunderbird |
|---|---|
| Email Clients | Microsoft 365, IMAP, Google Workspace (formerly G Suite), Outlook.com (Microsoft 365), and GoDaddy (Microsoft 365) |
Break down all the OST/PST components across licences and save accordingly.
Emails
HTML Body Content/Plain Text: Transfer all your email, including the To, Subject, CC, Bcc, From, Time, Date Sent/Received, and links in one easy transaction with a single click.
Attachments: Easily transfer normal and embedded email attachments like:
Metadata: Captures and preserves the Sender, Recipient, CC, and Bcc email addresses, subject line, timestamps, and headers precisely for accurate tracking of OST/PST data.
Folder Structure: Email files, folders, subfolders, and nested folders are preserved as they were originally saved in Outlook. The Microsoft OST to PST Converter does not change the folder hierarchy. Everything is originally organized.
Calendar & Contacts
Calendar: Outlook OST Conversion Tool manages calendars and associated details (subject, location, reminder, start time, end time, date, attachments, and other event body details). You can convert OST to ICS to preview all tasks, recurring/scheduled meetings, appointments, reminders, and events directly on a daily, weekly, monthly, or yearly basis. Directly import into Outlook Calendar, Apple Calendar, or Google Calendar for ease of use.
Contacts: Find all of the important people you have done business with over the years in Microsoft Outlook as CSV/VCF contacts. Export their Name, Company, Email, Dates, Phone, and Notes information from multiple OSTs into the local desktop versions.
Others
Notes: Learn about the Subject, Created Date and Time, and Content within your Notes.
Tasks: Check your Subject, Status, Start Date, End Date, Time Zone, Sensitivity, History, Owner, Assigner Name and Email, and Notes details of your tasks completely.
Headers: Verify the From, To, Subject, Date, Reply to, Message ID, Priority, and Importance details for the data within your OST files with the best OST to PST Converter Tool.
MIME and RAW HTML: Know how all your email metadata, routing, headers, etc., is bundled together and what HTML tags are used to set the visuals and structure of your mailbox content.
Preview them with no complexities and store them separately as desired. Check their attachments in the Attachments tab and save them with no data loss.
Detailed features of the offline OST to PST Converter enable complex conversions to be dealt with feasibly.
Cross-Format OST File Conversion
Save your archived OSTs in 13 dedicated formats for high precision. Convert OST to MBOX, PST, PDF, Thunderbird, CSV, and others, eliminating platform dependency with secure offline, local processing on the OS and no server uploads. Maintain original data fidelity and use the resultant files across platforms.
Direct Local to Cloud Migrations
Straightforwardly import OST file to Office 365, Google Workspace, IMAP, Outlook.com, and GoDaddy with advanced OAuth authentication, JSON Key Uploads, and App Passwords for extreme data security and no risks, and without credential storage. Preserve complete data, including user-level permissions for max efficiency.
High-Speed Bulk OST Processing
SysInfo OST to PST Converter allows you to process multiple OST and PST files in large batches with attachments and no size limitations simultaneously in a single session. Convert 100s or 1000s of OSTs with manual uploads via Select Files/Select Folders or drag and drop for timely migration across projects.
Preview and Smart Search Emails.
Evaluate the content within your OST mailbox files and folders with the 10-tab preview displaying Body, Attachment, Text, Calendar, Contacts, Notes, Tasks, Headers, MIME, and RAW HTML. Preview in the software or web and use Search and Advanced Search for specific email identification pre-conversion.
Targeted Outlook Data File Exports
OST Converter Pro supports Date Range (Start Date and End Date) filtering to download/export only particular emails, avoiding clutter in the resultant file.
Skip Redundancy to Optimize OST
Using the OST File to PST Converter Tool, you can remove Duplicates based on To, From, Subject, Body, and CC to keep the resultant output clean and useful for all users.
Precise Zero Data Loss Conversion
Maintain your folder hierarchy and fidelity preservation to ensure that the entire OST file conversion is flawless. Use the Skip Previous Exports feature to organize data and avoid duplication of the emails while converting to the desired output at a location of your choice.
Organized OST Mailbox Handling
Use any of the three modes to deal with your OST attachments. Either export them separately, merge them, or completely exclude them to maintain your data in order, with no overfilled storage. Handle them accurately for optimum use, whether for compliance or other tasks.
Adaptable Outlook OST Data Backup
Backup your Outlook OST data with the SysInfo OST to PST File Converter in different formats. Split oversized PDF (Upto 500MB/Folder), PST, and MBOX (Upto 999MB or 50 GB/Folder) files to make sure content is easily retrievable.
Effortless and Clean Data Management
Manage your large OST datasets and save them with different File Naming Patterns or a Custom Name for quick identification, and map data with the default mailboxes or follow the tree hierarchy when saving to other clients.
Designed for Simplified Transfers
Use the simple, user-friendly, intuitive interface without any technical proficiency. Ge benefits from secure modern authentications during transfers to the cloud and checks conversion completion with export logs for verification.
Risk-Free Multi-Platform Access
Microsoft OST to PST Convert Tool is highly compatible with all Windows (11, 10, 8.1, 8, and lower versions, 32-bit and 64-bit) and Mac OS. It even supports OST files (ANSI/UNICODE) from all Outlook and Exchange versions and saves 50 emails/folders via Demo.
Go through the specifications of this SysInfo OST to PST File Converter Software so that you can install it quickly.
| Version: | 26.6 |
| Size: | 245 MB |
| License: | Multiple User |
| Release Date: | 19 June 2026 |
| Edition: | Single, Admin, Technician & Enterprise |
| Free Download Buy Now |
| Processor: | Intel® Core™2 Duo E4600 Processor 2.40GHz |
| RAM: | 4 GB (8 GB Recommended) |
| Disk Space: | Minimum Disk Space - 1 GB |
| Supported Windows: | 11, 10, 8.1, 8, 7, 2008, 2012 (32 & 64 Bit), and other Windows versions. |
| Support Outlook Versions: | Outlook 2024 (LTSC), 2021, 2019, 2016, 2013, 2010, 2007, 2003, 2002, 2000, and Outlook Express 4.0–6.0 (ANSI and UNICODE) |
| Supported Exchange: | Exchange 2019, 2016, 2013, 2010, 2007, 2003, 2000, 5.5, 5.0 · Microsoft 365 / Exchange Online |
| Supported Mac: | MacOS X 10.8 (Mountain Lion), MacOS X 10.9(Mavericks), MacOS X 10.10 (Yosemite), MacOS X 10.11 (El Capitan), MacOS X 10.12 (Sierra), MacOS X 10.13 (High Sierra), MacOS X 10.14 (Mojave), MacOS X 10.15 (Catalina), MacOS X 11.0 (Big Sur), MacOS X 12.0 (Monterey), MacOS X 13.0 (Ventura), MacOS X 14.0 (Sonoma), MacOS X 15.0 (Sequoia) and above versions with M Series. |
| The trial version of the SysInfo OST to PST Converter allows you to evaluate the entire software functionality. Even save upto 50 emails per folder on your local OS without Outlook access. For complete mailbox conversion with full functionalities, upgrade to the premium version. |
Follow this stepwise procedure to convert OST/PST files into various formats or export to clients with ease.
SysInfo's Award-Winning Software Recognized by Experts- Highly Rated in the Best Category
TechRadar considers SysInfo OST File to PST Converter an enterprise-grade software solution providing a user-friendly interface for all tech and non-tech users. It is designed precisely considering all user requirements with offline exports for inaccessible, orphaned, healthy, oversized, and protected OST/PST files, making it empower over other third-party utilities in the online marketplace. View more
ITQlick rates SysInfo OST Conversion Tool 4.9/5 for its high-speed performance of batch OST conversions for multiple files without Outlook installation. With high forensic precision and simplified preview across several tabs, it ensures a hassle-free experience for all users through the self-explanatory interface, usable on Windows and Mac OS. Highly recommend this secure, reliable, and powerful OST file conversion solution. View more
A mid-sized organization executed rapid cloud domain and tenant migrations. However, they were left with approximately 1600+ large inaccessible OST archives after the old Microsoft 365 tenant account was deleted/unlinked. The unsynced local calendar subfolders and archives went missing, too.
Outlook required the active profile to access OST files natively on the system with a built-in wizard. But its absence resulted in "The file xxx.ost cannot be opened.” errors with manual conversions. The data was trapped in the 40GB+ files. To ensure data safety, IT Admins and remote employees trusted the SysInfo OST to PST Converter Tool and converted all their inaccessible OSTs into PST at a large scale in a single go. Every metadata, emails, attachments, and other mailbox items were kept intact with no loss, and the organization resumed business operations in minimal time successfully.
Fully functional trial with no surprises to evaluate the software against actual OSTs before the final purchase.
| Product Features | Demo Version | Full Version |
|---|---|---|
| Convert OST to PST, EML, JSON, CSV, DOCX, MBOX, etc. formats | Only 50 Emails Per Folder | All |
| Export OST files to Google Workspace, M365, IMAP, Gmail, and others | Only 50 Emails Per Folder | All |
| Handle Large and Bulky OST File Conversion | ||
| Convert OSTs without Outlook/Exchange or M365 | ||
| 10-tab Email Preview +Browser View | ||
| Eliminate Identical Emails | ||
| Divide Large Output PST, PDF, and MBOX Files | ||
| Save Attachments in a Separate Folder | ||
| 3 Modes to Handle Attachments | ||
| Skip Duplicate Emails | ||
| Custom Naming and Destination | ||
| Skip Previously Migrated Emails | ||
| Secure Modern Client Authentication | ||
| 24*7 Tech Support & 100% Secure | ||
 |
Download | Buy Now |
SysInfo, with 15+ years of experience, guarantees data security with 100% offline processing and no server uploads. Your OST data is a strict read-only source that is never mounted to Exchange, modified, altered, or exposed to risks. It ensures that every software delivered is standalone with no Outlook, Exchange, or domain dependency and downloads on the user's machine, whether Mac or Windows, in no time. Designed with a forensic-grade preview across multiple tabs for precision and streamlined downloads into numerous formats and exports to email clients. Finally, with full MAPI metadata preservation and batch processing of dozens of large OST archives, it ensures complete user satisfaction.
For more queries, reach out to the technical expert support via Live Chat 24/7.
Deep technical answers to all common user queries with precise context of software benefits.
Ans: 6 GB of locked OST or even more with a dead Exchange Server is easily accessible with this standalone, independent OST to PST File Converter Tool. It requires no Outlook installation, Exchange server connection, or Microsoft 365 subscription, and allows you to open, view, and read OST and convert it into PST for simplified access in Outlook.
Ans: New-MailboxExportRequest in Exchange PowerShell runs on the server-side to fetch data and requires an active connection and technical expertise. Whereas the OST Converter Pro needs no connectivity or technical proficiency. It has a user-friendly interface and works flawlessly everywhere, whether on Mac or Windows.
Ans: PST is ideal for archival and portability for all accounts without Exchange, and OST is the offline cache file for Exchange. The default location of the OST data file is C:\Users\%username%\Documents\Outlook File. If considering backup, migration, and accessibility, PST is better since it doesn’t restrict opening only to the creation system.
Ans: When using SysInfo OST to PST Converter, you can ensure a smooth and quick processing for converting multiple OSTs in batches. Also, once the conversion is processed, it displays the status in the end panel and provides an export log, which you can analyze if the process failed and restart the conversion.
Ans: All your email content, attachments, metadata, timestamps, MIME, Raw HTML, and other items remain preserved whether you convert once or more than once. Even if the process is interrupted, with Skip Previous Export, you can recontinue without any chance for redundancy of the mailbox data.
Ans: The demo version of the software limits you to converting only upto 50 emails per folder with other items for evaluation purposes. But all the other Single, Administrator, Technician, or Enterprise licences are valid for as long as you need them without any restrictions on the size or number of OSTs for conversion.
Ans: The software is designed to access OSTs locally and runs on your local machine, completely offline. It has no data uploads to the server or connection with other utilities, and opens and views your important and sensitive OSTs and attachments in read-only mode. Even the conversion to the format of your choice takes place with complete data fidelity.
Ans: If you have local OST archives of the decommissioned Exchange profiles, then SysInfo OST File Converter allows you to convert data from all 10 profiles at once. Simply, upload your OSTs, preview them to verify integrity, select folders, choose the format/email client, and complete the conversion without active Exchange.
Ans: With the latest MS Outlook editions, OST is generated when users configure MS Outlook with IMAP protocols to save the data. If configured with POP3, PST will be generated, but if POP3 is configured and Outlook is connected to the Exchange, then the OST file will be generated.
Ans: OST files are bound with the profile they were created in and are highly prone to corruption and data loss if the profile becomes inaccessible. They can’t be opened with Outlook, either, though it provides high security. Therefore, it becomes essential to export OST to MSG, PST, CSV, EML, JSON, and other formats to keep it secure and accessible in the long run, with or without an active profile.
Get to know what our client reviews say, as stated by trusted professionals, teams, and enterprises globally.
Step 1: Install and run the SysInfo OST to PST Converter Pro on your OS.
Step 2: Click any of the 3 options to upload files and load OST/PST files and folders. Tap Proceed.
Step 3: Expand the tree folder hierarchy, preview your files, and select the folders for conversion. Tap Proceed.
Step 4: Choose the file format/export client to which you want to save OST files.
Step 5: Click Browse from output location and select the folder where you want the resultant data. Tap Start Export.
Step 6: Finally, the process of conversion executes. Check the status, close the tab, restart, or download export logs on the OS. .
