Dear Sir,
We did many games similar to your Chatting game idea and we can provide full smoothest gameplay and stunning experience.
We checked attached file and we can make it perfect with good, reliable and optimized backend REST APIs for all its functions.
We did over 170 games for worldwide publishers giving them much more than needed, having full infrastructure and expertise for making them, with over 80 employers, project managers and experts in all field of game development.
With HQ in London, and developments in Belgrade, Hong Kong, Switzerland, Austra, we have experts in all fields of game development, multiplayer, user interface, 2D, 3D modelers, graphic designers, server and backend and mobile options, iap, leaderboards, level designers.
We provide lifelong free maintenance and support on our productions, guarantying you best game development on Freelancer.
Here you can check our portfolio: https://www.freelancer.com/u/miodragstajic
Thanks,
Miodrag