log_sense is a command-line command which analyzes Rails and Nginx logs and provides detailed data about accesses, performances, and errors. It is a one stop shop solution for analyzing your Rails application in production. Simple to use and working offline, it does not require any modification to your app (e.g., no need to change the log format, no cookies, no JavaScript code, no infrastructure to setup). We use it to monitor our applications in production, using a cron job which pulls the logs and calls log_sense to generate HTML reports.