Hi ,
I am very much interested on your job & I can assure you that I will complete " External API Integration // Creating registration form on existing site " work in a very quick time .
I have worked on many custom API intergration , restful & external APIs .
I have much more experience on php , making custom API & other APIs like payment API , SMS API , facebook API , linkedin API, twitter API and google plus API etc .
Please do ping me here on chat to discuss more about the project.
Thanks and Best Regards,
Richestuser