Cross-Platform API Automation Expert Needed

I'm seeking a skilled developer to automate an API compatible with both Android and iOS platforms, as well as for a Webapp.

Key functionalities I require include:

- User authentication
- Data retrieval
- Data submission
- Assertions
- Transaction completion
- Error/exception handling

The automation should be implemented using Python, JavaScript, Flutter, and HTML.

As a suitable candidate, you should have:

- Extensive experience in API automation
- Proficiency in Python, JavaScript, Flutter, and HTML
- In-depth knowledge of Android and iOS platforms
- A keen eye for handling errors and exceptions
- Proven record of successfully completed projects in API automation
- Strong attention to detail and problem-solving skills

Please bid if you're confident in your ability to deliver this project efficiently and effectively.