turnstile-rb

https://github.com/kigster/turnstile-rb

Turnstile is a Redis-based library that can accurately track total number of concurrent users accessing a web/API based server application. It can break it down by "platform" or a device type, and returns data in JSON, CSV of NAD formats. While user tracking may happen synchronously using a Rack middleware, another method is provided that is based on log file analysis, and can therefore be performed outside web server process.