Are there any ETL tools available to export data from RavenDB? Or will I be forced to write c# code to do the data migration?
The RavenDB is version 1 (build 888).
Yes, it is builtin to the product. See: https://ravendb.net/docs/article-page/3.0/Csharp/server/bundles/sql-replication/basics
It looks like the creator of RavenDB also created Rhino ETL to help with ETL. But it looks to be a .NET extension. Googling "RavenDB ETL" mostly came up with Rhino ETL.