Web Service Development for Data Storage

Looking for an engineer(s) with good web service development to develop a service to store data coming from end user accounts. Service should be able to have multiple to unlimited client accounts that end users can sign into to view and process their data. Client databases should be for the authorized client only. Data comes from an Android mobile phone with built in scanner to collect the data, and PC based USB barcode readers. Reporting component to run specific reports on collected data. User friendly UI as client will access this service directly. Project will start with data storage for clients to write to and access for data sharing among multiple client sites.