Looking for Salesforce API developer to Insert and update Salesforce Data into External system

I am looking for a Salesforce API developer who can help me with inserting and updating Salesforce data into an external system.

Specific Salesforce Objects:
- I need to insert and update data for Cases and Contacts.

External System:
- I have a specific system in mind that I would like to integrate with Salesforce. This can be a Postman or a simple system we can build using MangoDB, Readact, Node etc., to showcase the Integration

Data Mapping:
- The data mapping between Salesforce and the external system will involve field to field mapping.

Ideal Skills and Experience:
- Proficiency in Salesforce API development
- Strong knowledge of Salesforce objects and data manipulation
- Experience with integrating Salesforce with external systems
- Familiarity with field to field mapping and data synchronization
- Ability to understand and implement business logic for data mapping
- Strong problem-solving and troubleshooting skills
- MERN stack is an added advanrage
This work is only proof of concept to show how it works at high level, setting up a Integration user in Salesforce, few example of Adding/updating cases in Salesforce sandbox