Free online OST to VCARD converter

What the OST format is

OST, or Offline Outlook Data File, is a local cache created by Microsoft Outlook for Microsoft 365, Exchange, Outlook.com, and some IMAP accounts. It stores synchronized mail, calendar entries, tasks, and contacts so Outlook can work when the account server is unavailable.

An OST is tied to the Outlook profile that created it. Outlook normally opens it through that profile rather than treating it as an independent document, and an orphaned or damaged OST may require a specialized recovery tool before its contacts can be extracted.

What the VCARD format is

vCard is a contact-exchange format commonly saved with the .vcf extension. It can contain names, telephone numbers, email addresses, postal addresses, organizations, notes, web addresses, photographs, and other contact properties.

Phones, address-book applications, CRM systems, email clients, and operating systems can import vCards. A vCard file can contain one contact, while a vCard collection can contain multiple contacts; compatibility is generally best with vCard 3.0 or 4.0 and UTF-8 text.

How to actually convert OST to VCARD

Use Outlook to export contacts

1. Open the Outlook profile associated with the OST and wait for the Contacts folder to finish synchronizing.
2. Open People or Contacts and confirm that the required contacts are present. If the contacts are in a subfolder, open that folder instead.
3. For a small number of contacts, select a contact, choose Home → Forward Contact → As a Business Card, and save the resulting vCard attachment. Repeat for each contact.
4. For a larger set, use Outlook automation to save each contact as a separate .vcf file. Outlook must be installed and the correct profile must be loaded.

$outlook = New-Object -ComObject Outlook.Application
$namespace = $outlook.GetNamespace("MAPI")
$contacts = $namespace.GetDefaultFolder(10)
$output = Join-Path $env:USERPROFILE "Desktop\VCards"
New-Item -ItemType Directory -Force -Path $output | Out-Null
$number = 1
foreach ($item in $contacts.Items) {
    if ($item.MessageClass -eq "IPM.Contact") {
        $file = Join-Path $output ("contact-{0}.vcf" -f $number)
        $item.SaveAs($file, 6)
        $number++
    }
}
$outlook.Quit()

Save the commands as export-contacts.ps1 and run them in Windows PowerShell after Outlook has opened the required profile. The value 10 selects the default Contacts folder, and the value 6 tells Outlook to save contacts in vCard format. This script does not automatically traverse contact subfolders.

Use the built-in online converter

You can also use the free converter on 101convert.com: select OST as the source format, VCARD as the target format, upload the file, start the conversion, and download the resulting .vcf file. Uploading an OST may expose personal or business contact data, so use desktop extraction instead for confidential information or files covered by retention rules.

Quality and compatibility limitations

An OST-to-vCard conversion extracts contact records; it does not convert messages, calendars, tasks, or the Outlook folder structure into vCards. If the OST is encrypted, corrupted, incomplete, or disconnected from its original account, a converter may recover fewer contacts or require the original Outlook profile.

Outlook may omit custom fields, categories, distribution-list membership, synchronization metadata, and some contact photos. After conversion, import a sample into the destination application and check names, international phone numbers, Unicode characters, email addresses, photographs, and duplicate records before importing the complete set.