I'd recommend you to watch this talk https://www.infoq.com/presentations/SalesForce-Multi-Tenant-Architecture-Craig-Weissman https://www.infoq.com/presentations

I'd recommend you to watch this talk https://www.infoq.com/presentations/SalesForce-Multi-Tenant-Architecture-Craig-Weissman https://www.infoq.com/presentations/SalesForce-Multi-Tenant-... I've been dealing with different CRMs recently (SFDC, Netsuite, MS Dynamics, AgileCRM) and I don't think tools really matter, architecture that will allow you to customize everything is the key for CRM As my personal choice it would be (I'm a full-time Python dev) * Java/C# (there's nothing really dynamic in crm, entities, fields, etc with different "name" and "display_name" for each customer, IDE would allow me to manage complexity) * PostgreSQL (no NoSQL, CRM is all about relations) * Vue.js * ElasticSearch (with Kafka for replication from db) * RabbitMQ for offline jobs