Use cosmosdb for small businesses

Hello khoinguyenict, really hard to say without more information.

Whether or not to use CosmosDB depends on many factors. Let's look at its strengths:

• Massively scalable
• Really good at storing related data without requiring a strict definition
• Very, very fast

Take a look at https://docs.microsoft.com/en-us/azure/cosmos-db/use-cases

So yes, CosmosDB could be used but so could other repository technologies so I would think about how your application will be used. The biggest factor to me is the existing skillset of the team(s) that will be building the software. Budget is also another consideration; there might be less expensive alternatives. What High Availability requirements are there? Where is the customer base (global)? Does all the data need to be available to all locations? 

So, the question is not really a yes or no question.