5 Best PST Merge Software

Microsoft Outlook is a leading email client that organizations use for business communication. The application creates OST files for IMAP and MAPI email accounts and PST files for POP3 email accounts. If you need to export mailbox data from Outlook, then you’ve to save it in a PST file, irrespective of your account type.  

Why Outlook Users Need to Merge PST Files?

Outlook users may need to merge PST files for various reasons. Some common reasons are:

  • Migration to Another Email Client: If you are migrating from Microsoft Outlook to another email client, you can merge all your PST files into a single PST. This helps you to easily transfer all your emails and other mailbox items to the new platform when all your data is in a single file.
  • Merging Multiple Outlook Accounts: If you are using different email accounts for personal emails, work emails, and social media emails, then you may have multiple PST files. If you want to unify these accounts, you can simply merge PST files and import the resultant PST into a new account.  
  • Upgrading to Newer Outlook Version: In older Outlook versions, for instance, in Outlook 2007, the largest supported PST file size is 20 GB. So, users of this particular Outlook version had to create multiple PST files to store all their emails. In newer Outlook versions (2010 and above), the limit is 50 GB. So, if you are upgrading to a higher Outlook version, you can merge old PST files into a single PST.  

If you’re looking for software to merge PST files, below we’ve mentioned some reliable and easy-to-use software that can help you merge PST files.

Best PST Merge Software

Here are the top 5 PST merge software that can effectively and safely merge PST files:

1. Stellar Merge Mailbox for Outlook

Stellar Merge Mailbox for Outlook

Stellar Merge Mailbox for Outlook is an advanced software that merges or joins PST files of all sizes. It merges PST files with 100% accuracy and ensures there is no data loss during the process. It can merge all PST items, including emails, calendars, notes, contacts, etc. in a new PST that retains the original structure of the PSTs.


  • Merges or joins PST files with safety
  • Saves the merged data in a new or existing PST
  • Offers free preview of Outlook data files before merging
  • Exports the final PST file to Outlook profile, Office 365 account, and Exchange Server
  • Compatible with all Outlook versions: Outlook 2019, 2016, 2013, 2010, and even older versions
  • Removes duplicate emails from the merged PST
  • Removes deleted emails and junk emails during PST merge
  • Generates detailed log reports for each session

2. Advik PST Converter

Advik PST Converter

Advik PST Converter is a powerful software program that converts PST files into more than 35 file formats. These file formats include PDF, EML, MBOX, etc. Apart from converting PSTs, the application also merges and splits PST files.


  • Merges PST files of all sizes into a single PST
  • Retains the original folder hierarchy and meta data of the PST files
  • Repairs Outlook data files
  • Allows selective merge
  • Compatible with most Windows and Outlook editions

3. SysTools PST Merge Tool

Systools PST Merge Tool

SysTools PST Merge Tool is another advanced application that can merge PST files in both UNICODE and ANSI formats. It offers two options to add PST files – join and merge. It offers an intuitive UI that makes merging PST files easy and simple.


  • Merges all contents of PST files: emails, contacts, tasks, etc.
  • Offers two options for combining PST files: merge and join
  • Merges password-protected, active, and network Outlook data files
  • Allows merging of selective folders from different PST files
  • Removes duplicate items when merging Outlook data files

4. KDETools PST Merge Tool

KDETools PST Merge Tool

KDETools PST Merge Tool is a highly refined software application that uses advanced algorithms to perform accurate merging of PST Files. You can use it to merge multiple PST files into a single PST that contains all emails, attachments, contacts, etc. from the individual Outlook data files.


  • Offers different merging options – to merge emails, calendars, and contacts separately
  • Removes duplicate items when merging PSTs
  • Merges encrypted and network Outlook data files
  • Compatible with Outlook 2019, 2016, 2013, and earlier Outlook versions
  • Offers free preview of PST files before merging

5. MailsDaddy PST Merge and Join Tool

MailsDaddy PST Merge and Join Tool

MailsDaddy PST Merge and Join Tool is a simple and user-friendly application that allows you to merge two or more PSTs into a single PST.


  • Offers search option to automatically locate the PST files on your system
  • Omits duplicate items when merging
  • Supports password-protected Outlook data files
  • Compatible with both Unicode and ANSI PST files
  • No size limit for merging PSTs
free download


If you have many small-sized PST files, then merging them into a single PST makes it easy to organize and manage emails. Even though it is possible to merge Outlook data files within Outlook, using a dedicated PST merger tool simplifies the process and also reduces the risk of data loss. Above, you will find the top 5 PST merge software, along with their features. You can compare their features to pick the one that meets your specific requirements.

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