We came out of the gate with only a Ruby client, but now officially have a https://github.com/prefab-cloud/prefab-cloud-java client as well. Unfortunately customers do seem to want a bit of everything, C#, PHP, Node being the three that have been requested and I don't have experience in.
FeatureFlags got way more traction and interest than our original RateLimits. Decided that the ratelim.it domain name was fun, but was too confusing for a service that does a number of different things.
Needed to switch over from writing directly to DynamoDB to an async process that went through Kinesis. Wanted to do that with FeatureFlags so built them out... and made them our second feature.
Soft Launch
We originally launched in 2016 as ratelim.it. "Rate Limits as a Service". This scratched a very specific itch I had where I needed idempotency as a service at my day job.