Fluentd

Fluentd sits between your data sources and your backend systems as a single unified logging layer, so applications no longer need to know where their logs end up. It collects events from many sources and writes them to files, RDBMS, NoSQL, IaaS, SaaS, Hadoop, and other destinations.

The core stays small while 500+ plugins handle the connections to specific inputs and outputs. Events flow as structured JSON, configuration is driven by a fluent.conf file, and a third-party security audit by Cure53 has been published. It runs as a Ruby gem on Linux and Windows.

Fluentd is a CNCF graduated project licensed under Apache 2.0. Install it locally with gem install fluentd, then route events through your config; there is no hosted service from the project itself. It is maintained by the Fluentd Authors, with docs, GitHub discussions, and a Slack community.