Building a Communications Service API & Backend (Email, SMS, Push Notifications)

Looking for experienced back end developers who have experience building highly modular and efficient service layers and backend frameworks. This project is a gateway module to a series of modules that are to be developed so we're looking to establish a 6-12 month relationship with a developer or agency. Details: 1. Service Layer: RESTful API to enable sending of emails, sms and push notifications and various other features surrounding digital communication like creation of templates, variable replacement, etc. 2. Backend: An IFTTT engine to allow for sending of alerts if certain triggers are met, a job execution framework on which all backend jobs will execute. Detailed information and sample API calls are available to those who are interested. Prior experience writing micro-services/developing on a serverless platform is a plus. Please answer the following questions in your proposal: Please describe relevant projects that you have developed along with supporting documentation if any What challenging part of this job are you most experienced in? What questions do you have about the project?