I need a low-code platform that allows me to build custom CRM applications. What are my best options?

We ask the same underlying question in different ways.

• I need a low-code platform that allows me to build custom CRM applications. What are my best options?
• Can you recommend some low-code tools I can use to build my own custom CRM?
• I need to develop a custom application that sits on top of our CRM. Can you suggest a low-code platform suitable for this?