Suggestions for Financial Programs

I'm curious what financial programs everyone uses with an API connection to Workfront?

My team recently merged with a team that has billable clients and used Advantage. We agreed to use Workfront for project management but our billing coordinator is manually entering financial details into Advantage (generating invoice, billing rates, tracking expenses) because they have a closed API.

Our account managers and project managers enter the financials into a project billing record, I created a report for our billing coordinator to have that data in one place, then she manually copies and pastes to Advantage.

Any advice, suggestions, recommendations for a financial program that connects to Workfront and eliminates most of the manual process would be great!