Can we write from another app via an api into QBO estimates?

Hello, @kyya-2264.

Yes, you can write an estimate via API. Let me route you to the dedicated support forum so you'd be guided properly. 

1. Go to https://help.developer.intuit.com/s/.
2. Select API Docs & Tools.
3. Choose QuickBooks Online.
4. Hit Ask a QUestion.

Also, you can visit our QuickBooks API Blog, so you can get recent news and updates about this topic. 

I want to make sure everything is taken care of for you, so let me know if you have any other questions or concerns in the comment section below. I'm always here to help. Have a good one!

@kyya-2264 

If you are a developer, go to the link mentioned by IamjuViel 

If you are a user want to import Estimate data into QBO, explore this app

https:// transactionpro.grsm.io/qbo