Observability / APM

Sentry

Functional Software, Inc.

Error monitoring that grew into developer-first APM — connects errors → traces → spans → profiles → replays in one workflow, aimed at app developers.

Category
Observability / APM
License
Open core
Deployment
SaaS or self-hosted
Cost
Low
Free tier
Yes
Self-host effort
Moderate
Maturity
Incumbent
Popularity
≈40k+ GitHub stars; dominant in error tracking

The catch

It's APM from the app-developer angle, not infrastructure observability (no host/network/K8s monitoring), and span-based metering means high-traffic apps rack up span costs.

Monitors

TracesLogsRUMProfiling

Capabilities

AlertingDistributed tracingAPI

Built for

Developers