The value prop is definitely very similar. I'm not as familiar with Voltage as I am with other solutions, but my understanding is that it requires either using the Voltage database driver (JDBC/ODBC in particular) or an HTTP API.

With JumpWire, all of the works happens in an engine proxy that works directly with the database protocols. That makes the integration simpler - any language and connector can be used by just changing the hostname and auth. The downside is it's harder for us to add new databases - Voltage's approach definitely wins out there.