It's great to see you here today, nithin@pixelscri. I'm here to ensure you'll get the right support in completing your task to integrate QuickBooks API with your mobile application. 

We have a separate and dedicated forum that handles API concerns for QuickBooks Online (QBO). This is where developers and business people like you engage with others to discuss programming and mobile app connection concerns. I'd recommend getting an account set up and posting your question from there. This way, our developers can provide you with the access token to get authorized and guide you to complete your task. Here's how:

1. Go to the Intuit Developer page.
2. Choose QuickBooks Online under What do you need help with?.
3. Click Ask a Question.
4. Log into your existing Intuit Developer Account or create a new one.
5. Enter the details of your concern.
6. Select Ask.

Also, you can always utilize the helpful API topics by going to the API Docs & Tools menu. Then, select QuickBooks Online and choose API Explorer.

You can count me in if you have other concerns about connecting third-party apps and questions about managing transactions in QBO. I'll gladly help. Take care, and I wish you continued success, nithin@pixelscri.