Create API so my customers can access Email validation service -- 2

I have an Email marketing application called MailWizz from where my customers create and send campaigns, but they also can validate their email lists for an extra cost. That email validation is performed in the backend by MillioVerifier.com

Currently, the email validation process runs from client GUI (1. Buy email validation credits 2. Upload CSV file 3. CLick on validation button 4. - Email validation is done using API 5. Customer balance is automatically updated).

Now I would like my customers to have their own API URLs so they could integrate them with their systems. (1. Buy email validation credits 2. Use API 3. Customer balance is automatically updated).

I would like to provide my customers same features (Single API and Bulk API) from MillionVerifier.com but off course masked with my domain.

Programming Language: PHP

Email Validation Service: Yes, I have a specific service in mind.

Expected API Calls per day: More than 10,000

Skills and Experience Required:

- Strong proficiency in PHP programming language
- Experience with creating APIs and integrating them with external services
- Knowledge of email validation services and their APIs
- Ability to handle high volume of API calls efficiently
- Attention to detail and ability to ensure accurate email validation results
- Strong problem-solving skills and ability to troubleshoot any issues that may arise

If you have the necessary skills and experience to create this API, please submit your proposal.