There are 2 repositories under apm-client topic.
scouter-paper is a web client software for scouter
LinkAgent is a Java-based open-source agent designed to collect data and control Functions for Java applications through JVM bytecode, without modifying applications codes.
opentelemetry php extension
Web App performance and exception monitor
Sample application that demonstrate integration between Spring Boot and Elastic APM.
Sample NodeJS APM Client to get started with Distributed Tracing using Elastic APM.