New Relic

Pingdom

pingdom.com

Website performance monitoring made easy. Pingdom helps you gain instant insights into your website’s availability and performance so that you can outsmart competition with an amazing end-user experience.

Scout APM

scoutapm.com

Rails Monitoring, Django Monitoring, Elixir Phoenix Monitoring, PHP Laravel Monitoring, and more that identifies slow database queries, memory leaks, and more. Scout APM is cheaper, startup-friendly, and easy to use, but doesn't support as wide a range of stacks or features.

DataDog

datadoghq.com

Logging: Quickly search, filter, and analyze your logs for troubleshooting and open-ended exploration of your data. Explore and analyze logs from all your services, applications, and platforms. Search and filter your logs using automatically generated facets. Visualize log data on dashboards or build sophisticated alerts. DataDog is super capable and enterprise scale, but on the more expensive end. APM: Monitor, troubleshoot, and optimize end-to-end application performance.

Amplitude

amplitude.com

Amplitude is a product analytics service that makes it easier for companies to understand user behavior, ship the right features and improve business outcomes.