Hello,
I have gone through your requirement that you need to Extend Existing opencart app.
Please share your details so can go through it and start according. I have 5+year of experience in all areas of developing app and website like restaurant, social media, dating, event, uber, gps tracking, handy, classified(buy & sell) and many more.
I built 100+ app successfully.
"Satisfaction, quality of work " is my first priority.
Awaiting for your response.
Thanks
Anamika