Logstash is described as 'open source, server-side data processing pipeline that ingests data from a multitude of sources simultaneously, transforms it, and then sends it to your favorite "stash."'. There are more than 50 alternatives to Logstash for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and Self-Hosted solutions. The best alternative is Prometheus, which is both free and Open Source. Other great apps like Logstash are Sentry (Freemium), Kibana (Paid), Datadog (Paid) and Graylog (Free, Open Source).
Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. Since its inception in 2012, many companies and organizations have adopted Prometheus, and the project has a very active developer and user community.
Datadog is a monitoring service for IT, Dev & Ops teams who write and run applications at scale, and want to turn the massive amounts of data produced by their apps, tools and services into a unified view of IT infrastructure. 120+ Integrations!.
Graylog is an open source syslog implementation that stores your logs in Elasticsearch. It consists of a server and web interface written in Java that accepts your syslog messages via TCP or UDP (or GELF messages) and stores it in the database.
Splunk is software that provides unique visibility across your entire IT infrastructure from one place in real time. Only Splunk enables you to search, report, monitor and analyze streaming and historical data from any source.
Telegraf is a metric collection daemon that can collect metrics from a wide array of inputs and write them into a wide array of outputs. It is plugin-driven for both collection and output of data so it is easily extendable.