• Prometheus is a popular open-source monitoring and alerting system.
• Alertmanager is a component of Prometheus that handles alerts sent by server applications.
• Supports deduplication, grouping, and silencing of alerts.
• Allows for alert routing and notification configuration.
• Provides a web UI for managing and visualizing alerts.

• Grafana is a popular open-source visualization and analytics platform.
• Loki is a horizontally scalable, highly available log aggregation system.
• Allows for log aggregation and alerting based on log patterns.
• Provides a rich query language for filtering and processing logs.
• Integrates well with Prometheus for combined metrics and log analysis.

Prometheus+Alertmanager & Grafana+Loki do complement each other - Loki helps with creating alerts based on the application's logs, and Prometheus collects the metrics and reports everything to Alertmanager, which can then propagate the alerts to Grafana. Grafana can be the central part of the alerting system where every alert is then processed in a defined way.

• A popular commercial incident management platform.
• Provides alert aggregation, deduplication, and intelligent prioritization.
• Supports on-call scheduling and escalation policies.
• Integrates with various monitoring and collaboration tools.

• A modern incident management platform.
• Offers alert deduplication, suppression, and intelligent routing.
• Provides alert prioritization based on machine learning.
• Supports on-call schedules and escalation policies.
• Integrates with various monitoring and collaboration tools.