PHP script for API record submission to EspoCRM

We have an EspoCRM instance and require a simple PHP script to take user input on a form (no user interface design skills necessary) and to submit that form data to EspoCRM via the API. The functionality only requires submission of the data through the API with no validation of data - other than to check to see if a matching contact exists (by email address) and then create the relationship link in the submitted record, if it is found. If no match by email can be found, then the record is simply written to the CRM as is.