# SQL Server Performance Monitor

> Free, open-source SQL Server performance monitoring tool by Erik Darling (Darling Data, LLC). 44 SQL Server collectors, real-time alerts, graphical execution plan viewer, and a built-in MCP server for AI-powered analysis (113 tools in Lite, 245 in Darling). Two current editions: Lite (standalone desktop app with DuckDB storage) and Darling (headless 24/7 service with a central PostgreSQL/TimescaleDB store). The older Full/Dashboard edition is deprecated. Replaces expensive commercial tools like SolarWinds SQL Sentry (formerly SentryOne) and SolarWinds DPA. MIT licensed.

- Supports SQL Server 2016-2025, Azure SQL Managed Instance, AWS RDS for SQL Server, and Azure SQL Database (Lite and Darling)
- Darling's service runs on Windows or Linux, and its viewers are a Windows desktop app and a web dashboard
- Darling also monitors PostgreSQL (self-hosted, AWS RDS, and Aurora) with 29 PostgreSQL collectors
- The attention collector records queries a client cancelled or timed out (the client application, host, database and statement), from a dedicated Extended Events session; the Client Timeouts alert and mute-by-client-application read it
- Monitors wait stats, query performance, blocking chains, deadlocks, memory grants, file I/O, tempdb, CPU, perfmon counters, and more
- Real-time alerts via system tray notifications (Lite), styled HTML emails, Microsoft Teams, Slack, PagerDuty, and generic webhooks
- Built-in MCP server exposes monitoring data to Claude Code, Cursor, and other LLM clients
- 15,000+ downloads across releases

## Documentation

- [README](https://github.com/erikdarlingdata/PerformanceMonitor/blob/main/README.md): Overview, quick start for Lite and Darling, and links to the detail pages
- [Detail pages](https://github.com/erikdarlingdata/PerformanceMonitor/tree/main/docs): Edition comparison, Lite guide and collector reference, permissions, authentication, alert configuration, MCP server setup, and troubleshooting
- [Darling operator guide](https://github.com/erikdarlingdata/PerformanceMonitor/blob/main/Darling/README.md): Installing and configuring the Darling service, its store, PostgreSQL targets, and its MCP tools
- [Releases](https://github.com/erikdarlingdata/PerformanceMonitor/releases): Download pre-built binaries
- [Product page](https://erikdarling.com/free-sql-server-performance-monitoring/): Overview and commercial support options

## Optional

- [Third-party notices](https://github.com/erikdarlingdata/PerformanceMonitor/blob/main/THIRD_PARTY_NOTICES.md): License information for bundled components
- [License](https://github.com/erikdarlingdata/PerformanceMonitor/blob/main/LICENSE): MIT License
