Hot answers tagged 2007
CSOM and REST was introduced in SP 2010 so you wont be able to use that with 2007. SOM is an option but requires that your code runs on the servers of each farm. SharePoint Web Services will be your best option if you need to support all three versions with the same code from client computers. Lists Web Service (/_vti_bin/Lists.asmx) for getting libraries ...
CSOM: will work in SP online, SP 2010, 2013 and most probably 2016 REST: will work in SP online, SP 2010, 2013 and most probably 2016 OOTB Web service: will work in SP 2007, 2010, 2013 but maybe not in 2016 (and maybe not with future versions of SP online) Creating your own Web service with SOM: will work in SP 2007, 2010, 2013 and 2016
The client object model was created in 2010. CSOM did not exist in 2007. So I would recommend the server object model.
You can use any of these tools: Metalogix Avepoint Sharegate Metavis There are other tools as well. With the explorer view, you can not migrate metadata.
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