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The main alternatives to Stellar Merge Mailbox for Outlook are Outlook's free Import/Export wizard for a few healthy files, Microsoft 365's PST import for administrators loading files into cloud mailboxes, and paid merge tools such as Kernel PST Merge, SysTools PST Merge and Shoviv PST Merge. Compare their demo limits and licence terms with the $39.99 one year Standard edition before buying.
How to judge the alternatives
Every PST merge tool claims the same headline features, so the useful questions are narrower. What does the demo actually let you do: preview everything, or save the first few items per folder? Is the licence perpetual or one year? Does it keep each source separate, the way join mode does? Can it remove duplicates on chosen fields? Does it refuse damaged files, as this one does, or try to read them?
Read each vendor's own page and refund terms before paying. This page lists the options; it does not rank them on speed or reliability, because none of the vendors publish comparable figures. The benchmark for comparison is the one in the full review: $39.99 for a year, merge and join modes, eight field duplicate filter, five destinations.
Free routes from Microsoft
Outlook Import/Export wizard. Classic Outlook can import a PST into an open mailbox or data file and skip duplicates. It handles one file per run and keeps no log, but costs nothing. The comparison with the wizard goes through it point by point.
Microsoft Purview PST import. Microsoft 365 administrators can upload PST files and import them into users' cloud mailboxes. It is an admin tool for an organisation's tenant, not a desktop merger, and it suits moving many users' archives into the cloud rather than consolidating files on one PC.
Paid merge tools
Kernel PST Merge. A Windows merge tool that advertises merging and joining, password protected files and a skip duplicates option. Check its edition list and whether the licence is perpetual.
SysTools PST Merge. Another Windows tool for combining several PST files into one. Look at the supported Outlook versions on its page and what the free demo is allowed to save.
Shoviv PST Merge. A Windows merge tool with a demo version. Its page states the demo's item limit and the licence price; compare them with the preview only demo described on this site's download page.
Quick comparison
| Option | Cost | Best for |
|---|---|---|
| Outlook Import/Export | Free | Two or three healthy files |
| Microsoft 365 PST import | Included for admins | Loading many PSTs into cloud mailboxes |
| Kernel PST Merge | Paid, see vendor page | Comparing feature lists and licence terms |
| SysTools PST Merge | Paid, see vendor page | Comparing feature lists and licence terms |
| Shoviv PST Merge | Paid, see vendor page | Comparing demo limits |
| Stellar Standard | $39.99, 1 year | Many PSTs, join mode, fine duplicate control |
When to stay with the original
Its strongest points are a demo that previews the complete result before you pay, join mode, the duplicate criteria and Office 365 or Exchange as direct destinations. If your sources include Gmail, Microsoft 365 or Thunderbird, the Technician edition reads them too, which most simple PST mergers do not; the edition prices show the cost of that step up.
Compare with the demo in hand
Run the free preview on your own files, then hold the alternatives to the same test.
Frequently asked questions
What is the best free alternative?
Outlook's own Import/Export wizard. It imports one PST at a time into an open mailbox or data file and can skip duplicates, which covers small jobs.
Is there an alternative for Microsoft 365 administrators?
Yes. Microsoft Purview's PST import lets administrators upload PST files and import them into users' Microsoft 365 mailboxes. It is meant for organisations, not single PCs.
Which paid PST merge tools compete with it?
Kernel PST Merge, SysTools PST Merge and Shoviv PST Merge are direct competitors. Check each vendor's demo limits, licence term and refund policy before buying.
Do the alternatives repair corrupt PST files?
Merge tools generally expect healthy files, and this one refuses corrupt ones outright. Repair damaged files first with a dedicated repair tool or Outlook's Inbox Repair Tool.
Why not just keep several PST files open in Outlook?
That works and costs nothing. The drawback is several folder trees to search and several files to back up; merging leaves one file.