Fluentd: Unified Logging Layer (project under CNCF)
Ansible role which installs and configures Graylog
Apache Log Parser and Data Normalization Application
Elasticsearch/Splunk/Datadog alternative for (logs, metrics, traces)
Qualitis is a one-stop data quality management platform
Logging Framework for C++
A fake log generator for common log formats
Extensible log shipper with input/output plugins, buffering, etc.
Sematext Logs Client Library for Android
Open Source SIEM
Log Management Web Application