PerformanceMonitor

SQL Server Performance Monitor

Free, open-source monitoring that replaces the tools charging you thousands per server per year. It includes specialized collectors, real-time alerts, and a built-in MCP server for AI analysis. Nothing phones home. Your data stays on your server and your machine.

If you pay for a monitoring tool now, read the comparison for yours.

Redgate SQL Monitor · SQL Sentry · SolarWinds DPA · Idera SQL Diagnostic Manager · Quest Spotlight · Datadog Database Monitoring · Database Health Monitor

It supports SQL Server 2016 SP2 to 2025. SQL Server 2017 needs CU3 or later. It also supports Azure SQL Managed Instance, AWS RDS for SQL Server, and Azure SQL Database (Lite and Darling). Darling also monitors PostgreSQL, including AWS RDS and Aurora.

[Fleet overview: nine servers at a glance, one flagged Critical with live blocking and deadlocks]

Editions

• Lite is a single desktop app that monitors your servers remotely, on demand. Nothing is installed on your server. It stores data in local DuckDB and Parquet files.
• Darling is a service on Windows or Linux that collects 24/7 into a central PostgreSQL store. The Windows viewer and the web dashboard read that store from any seat.

Both editions can hand an alert to an AI agent that you run, and Lite lets the agent read and report. Darling can also let it change alert settings (mutes, custom alert rules and thresholds). On a server, it can force or unforce a Query Store plan, evict a cached plan or kill a session. Each of these has its own switch per server, and all are off until you turn them on. Darling records every change, and a person can undo alert-setting changes and plan forces but not a plan eviction or a session kill. Agent dispatch explains the levels.

The Dashboard edition is deprecated. Existing installs keep working, but we recommend Lite or Darling for new deployments. Choosing an edition compares all three.

Each release ships these downloads. For Lite, a Setup.exe and a portable ZIP. For Darling, the service ZIP (with the viewer inside), a Viewer Setup.exe for a remote seat, and the Linux and Compose tarballs. The Full Dashboard and its CLI installer ship nothing. Their last builds are in the v3.2.0 release.

Not sure which one? Start with Lite. It is one download, nothing is installed on your server, and data starts to flow in under 5 minutes.

Quick start: Lite

1. Download PerformanceMonitorLite-lite-Setup.exe. It is a self-contained build, so you do not install a .NET runtime first.
2. Run the installer. It adds Start Menu and Desktop shortcuts.
3. Start Lite from the Start Menu or the Desktop shortcut.
4. Click + Add Server, enter the connection details, test, and save.
5. Double-click the server in the sidebar to connect.

Data starts to flow within 1 to 5 minutes. The monitoring login needs VIEW SERVER STATE (Permissions).

Before you upgrade an older install with Setup.exe, read the warning in the Lite guide. On versions older than the data-relocation fix, Setup.exe deletes the data in the install directory. The Lite guide also covers the portable ZIP, collectors, storage, and configuration.

Quick start: Darling

1. Download PerformanceMonitorDarling-<version>.zip from the latest release. The machine needs the .NET Runtime 10 and the ASP.NET Core Runtime 10. The ASP.NET Core Hosting Bundle 10 installs both.
2. Copy darling.sample.json to darling.json and add your servers.
3. Run the service, in a console for a trial or as a Windows service.
4. Start the Darling Viewer from the viewer\ folder in the same zip.

These steps are for Windows. For Linux, the full steps, and the web dashboard, read the Darling quick start. If you have not done this before, docs/uat-onboarding.md is the ordered path from the zip to a working install. The Darling operator guide is the configuration reference.

Documentation

Support

Performance Monitor is free and open source under the MIT License, with no features withheld. The tools that it replaces charge thousands of dollars per server per year. A support subscription covers all of your SQL Server instances.

Support and sponsorship says what support gets you and has the link to buy. You can also sponsor on GitHub.

Sponsors

License

Copyright (c) 2026 Darling Data, LLC. Licensed under the MIT License. See LICENSE for details.

Author

Erik Darling: erikdarling.com and Darling Data, LLC