Low-code platform for CRM apps

If the goal is “build a custom application on top of an existing CRM”, my default recommendation is Retool—unless your CRM is Microsoft Dynamics/Dataverse, in which case Power Apps is usually the better choice.

My shortlist

Why I'd lean Retool

Retool is particularly well suited when the CRM remains the system of record and your new application is a custom experience around it. It can connect to APIs/databases, provide a custom UI, write back to CRM data, and handle permissions and workflows. Its Salesforce integration, for example, supports reading and modifying Salesforce records while respecting controlled access.retool.com

That makes an architecture like this attractive:

CRM → API/integration layer → Retool → custom application

You don't have to migrate your CRM data or recreate CRM functionality. Retool can essentially become the specialized application layer.

When I'd choose Power Apps instead

If your CRM is Dynamics 365, I'd strongly favor Power Apps. Dynamics 365 already uses Dataverse, and Power Apps can build directly against that underlying business data without a separate integration layer.learn.microsoft.com

Power Apps also gives you both model-driven apps (data/process-centric) and canvas apps (highly customized UX), plus Power Automate for workflows.learn.microsoft.com

So:

• Dynamics 365 → Power Apps
• Salesforce → Salesforce Platform or Retool
• HubSpot → Retool is worth a serious look
• Custom/proprietary CRM with APIs → Retool
• Need a major enterprise application, not just a CRM extension → Mendix/OutSystems

The biggest decision isn't actually the UI builder—it's how deeply you want the new application coupled to your CRM. Low-code platforms can accelerate development substantially, but licensing, governance, scalability, and vendor lock-in become increasingly important as the application grows.www.ciopages.com

If you tell me which CRM you're using (Salesforce, HubSpot, Dynamics, SAP, custom, etc.), who will use the app, and roughly what you want the app to do, I can give you a much more specific recommendation—including Retool vs Power Apps vs the CRM's native platform and an architecture I'd use.