Mozilla Thunderbird Extension openCRX

Josh Geenen - the developer of the famous gContactSync extension - developed a Thunderbird extension for openCRX. The extension is free. Download it from

Please note that this extension requires at least Thunderbird 3.0 (read and write contacts), available from

This Thunderbird extension provides integration of the Thunderbird Address Book with openCRX:

  • you can manage an address books associated URL directly from the address book properties:
  • you can Export an Address Book to openCRX - the exporter creates a VCARD for each contact in the respective Address Book, concatenates the VCARDS (i.e. builds a file or stream containing all VCARDS) and then uploads the file/stream with an http PUT request.
    Aside: There is a another wonderful Thunderbird Add-on MoreFunctionsForAddressBook, which also provides a function to export an address book as a sequence of VCARDS to a file.

  • you can Import openCRX Accounts to an Address Book; the importer fetches a file/stream of VCARDs with an http GET request and then creates (or updates if the UID machtes) a contact in the respective Address Book for each VCARD received.

There is no need for any synchronization code, i.e. we want to keep it simple. Either get an address book from openCRX (which will overwrite any changes made locally) or put an address book to openCRX (where the server will take care of any synchronization issues).