We have Quickbooks online and want to integrate salesforce so we can perform sales forecasts based on potential revenue from the estimates as well and weight the data with probabilities. Need advice on best add on app

For this kind of forecasting you’ll want an integration that can bring QuickBooks estimates into Salesforce and tie them to Opportunities, so the probability weighting works. Some teams go with AppExchange apps dedicated to Salesforce-QuickBooks sync, others use middleware to handle the mapping more flexibly. If you don’t want to manage custom code, Skyvia is worth a look. It can connect QuickBooks Online and Salesforce, sync estimates and opportunities, and keep the data ready for forecasting without manual exports.