For A/B tests implemented in backend code, I just use rand() to bucket a user, then store that bucket in redis. After it's been live for a while, I pull the da

For A/B tests implemented in backend code, I just use rand() to bucket a user, then store that bucket in redis. After it's been live for a while, I pull the data from redis then use this open-source calculator to view the results: https://thumbtack.github.io/abba/demo/abba.html https://thumbtack.github.io/abba/demo/abba.html For anything more complicated (e.g. split test shared across multiple systems, A/B testing multi-step funnels) I fall back to Kissmetrics.