Splunk is a comprehensive monitoring platform that provides service mapping, distributed tracing, code-level visibility, intelligent analytics, and advanced features such as real-time monitoring and observability. It offers a 14-day trial period and flexible pricing plans depending on workload, data, activity, or number of hosts. Datadog provides end-to-end distributed tracing, automated deployment tracking, synthetic monitoring, real user monitoring, service dependency visualization, and scalable pricing with a 14-day trial. New Relic offers infrastructure monitoring, distributed tracing, log management, synthetic monitoring, and pay-as-you-go pricing at $0.30/gigabyte above the free 100 GB data. Dynatrace provides deep transaction tracing capabilities, end-to-end visibility into application transactions, PurePath technology, and Davis AI engine for automation and intelligent analytics. AppDynamics offers comprehensive visibility, deep diagnostics, intelligent analytics to optimize application performance, and integration with Cisco's networking expertise. Sentry is a widely-used APM tool providing error monitoring, crash reporting, performance monitoring, transaction tracing, release tracking, and flexible pricing tiers including a free developer tier. Application Insights offers live metrics, distributed tracing, intelligent analytics, alerting, and monitoring, with Azure pricing tiers based on data volume and features. Paessler PRTG provides customizable reporting, distributed monitoring, intelligent network discovery, and scalable pricing based on the number of sensors used. Elastic APM leverages Elasticsearch to collect transaction logs, system metrics, user behavior data, and offers real-time monitoring, RUM, transaction sampling, logging integration, and cross-cluster search. InfluxDB is a high-performance time series database for storing, querying, and analyzing time-stamped data with features such as data collection, time series data models, data visualization, and query languages. SigNoz is an open-source APM tool providing distributed tracing, advanced filtering, custom aggregation, performance analytics, and flexible pricing plans including teams and enterprise tiers. SolarWinds AppOptics offers transaction tracing, live code profiling, exception tracking, root cause summaries, and seamless integration with other SolarWinds products. When choosing an APM tool, consider factors such as ease of use, scalability, pricing, features, and capabilities, and may choose to use multiple tools depending on specific needs.