PostHog

Cloud-scale monitoring, security, and analytics platform for modern infrastructure.

Datadog is a cloud observability and security platform that unifies metrics, traces, logs, RUM, synthetics, APM, and security signals. Current pricing pages list 1,000+ integrations for Infrastructure Monitoring, with Pro from $15/host/month and Enterprise from $23/host/month when billed annually.

Application monitoring and error tracking that helps developers fix issues faster.

Sentry is the leading error tracking and performance monitoring platform for developers. Captures and aggregates errors with full stack traces, breadcrumbs, and context across 100+ platforms. Used by over 100,000 organizations. Features session replay, performance tracing, and code-level profiling. A self-hosted deployment is available under FSL-1.1-Apache-2.0.

Open-source observability platform for metrics, logs, and traces visualization.

Grafana is the leading open-source platform for monitoring and observability visualization. It connects to virtually any data source — Prometheus, Elasticsearch, InfluxDB, PostgreSQL, CloudWatch, Datadog, and 150+ others — to create beautiful, interactive dashboards. Used by millions of users at companies like Bloomberg, JPMorgan, eBay, and PayPal. Grafana Cloud offers a fully managed experience with generous free tier. The CNCF ecosystem standard for metrics visualization.

Open-source LLM observability and evaluation

Phoenix by Arize is an open-source AI observability platform for tracing, evaluating, and debugging LLM applications. It captures prompt-response pairs, retrieval context, agent tool calls, and latency data through OpenTelemetry-based instrumentation. Provides experiment tracking, dataset management, and evaluation frameworks for systematically improving AI application quality. 10K+ GitHub stars.

Open-source LLM engineering platform for observability

Langfuse is an open-source LLM engineering platform with 29K+ GitHub stars for tracing, evaluating, and monitoring AI applications. Acquired by ClickHouse, it provides detailed traces of LLM calls, prompt management with versioning, dataset-based evaluation, user feedback collection, and cost tracking. Framework-agnostic with native integrations for LangChain, LlamaIndex, OpenAI SDK, and Vercel AI SDK. Offers both self-hosted deployment and a managed cloud service.

LLM evaluation and prompt engineering platform

Braintrust is an AI observability and evaluation platform for tracing LLM applications, building datasets, running prompt/model experiments, scoring outputs and turning production feedback into regression tests. It fits teams that need repeatable quality gates for AI releases rather than one-off prompt demos.

AI gateway with observability, routing, and guardrails

Portkey is an AI gateway and observability platform providing a unified API for 200+ LLM providers with intelligent routing, caching, rate limiting, and guardrails. Route requests across OpenAI, Anthropic, Google, and more with automatic failover, load balancing, and cost optimization. Features request logging, prompt management, evaluation tools, and real-time monitoring. The open-source gateway can be self-hosted; Portkey Cloud adds managed observability and team features.

Open-source monitoring and alerting toolkit — the CNCF standard for metrics collection.

Prometheus is the open-source monitoring system and time-series database that has become the CNCF standard for metrics collection in cloud-native environments. Features a powerful query language (PromQL), pull-based metrics collection, multi-dimensional data model, and built-in alerting via Alertmanager. The foundation of modern Kubernetes observability.

SigNoz is an OpenTelemetry-native observability platform for collecting and correlating logs, metrics, and traces. Teams can self-host it or use SigNoz Cloud, with dashboards, alerting, query workflows, and enterprise controls for cloud-native and AI application telemetry.