We more provide our best practices, knowledge and proficiency in business processes optimisation than just web or mobile services.
Upwork profile with 30+ straight 5 star reviews for the past several years from clients mostly from the US and Europe. No single 4 stars there:
https://www.upwork.com/agencies/~019c0c38c401264e32
Clutch profile with more reviews: https://clutch.co/profile/cookiedev