Newman Mail - A mail-merge service for Gmail with message A/B testing
I have been doing a lot of customer development lately and I needed a tool that made it easy to reach out to large-ish groups of people whilst testing the efficacy of different messages.
I chose to build my own product because I could not find another tool that was simple enough to use (all the others were full-blown CRMs), I did not want to pay for the subscription to those other tools and (most importantly) I wanted to use this project to learn a couple new things (Javascript ES6, using Google APIs, building task queues).
It's pretty rough and I built it just for myself (I don't allow signups because I took a couple security shortcuts in the design) but it works and has increased my productivity dramatically.
10/10 would code again