PerformanceMonitor MCP Server

SQL Server Performance Monitor

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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. It supports PostgreSQL 14 to 18, plus Amazon RDS, Aurora and Azure Database for PostgreSQL, and makes a best effort on PostgreSQL 10 to 13. See Supported PostgreSQL versions.

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 or evict a cached plan. It can recompile a module, create or drop a plan guide, 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. A person can undo alert-setting changes, plan forces and plan guide changes. A plan eviction, a recompile or a session kill cannot be undone. 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), an MSI, 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 four server grants: VIEW SERVER STATE, CONNECT ANY DATABASE, VIEW ANY DEFINITION and ALTER ANY EVENT SESSION. Without CONNECT ANY DATABASE, the per-database collectors skip the databases that the login cannot enter. The full grant block is in Permissions. If the first connection fails on a certificate error, see Troubleshooting.

Before you upgrade an older install with Setup.exe, read the warning in the Lite guide. On versions older than 3.4.0, Setup.exe deletes the data in the install directory (see Upgrading an install older than 3.4.0). The Lite guide also covers the portable ZIP (PerformanceMonitorLite-<version>.zip), collectors, storage, and configuration.

Quick start: Darling

1. Download PerformanceMonitorDarling-<version>.zip and SHA256SUMS.txt from the latest release. Check the zip hash against SHA256SUMS.txt. The zip carries its own .NET runtime, so there is nothing to install first.
2. Extract the zip to C:\Program Files\PerformanceMonitorDarling. Do not use your Desktop, Downloads, or any folder under C:\Users\. The service runs as a virtual account that cannot read a user profile (why).
3. Double-click Install-Darling.cmd in the install folder. It asks Windows for administrator rights and runs install-darling.ps1. You can also run .\install-darling.ps1 from an elevated PowerShell. It installs the Windows service and creates a Darling Viewer shortcut. With no darling.json it writes a minimal one, and the service starts with no monitored servers.
4. Wait for the installer to print Service is ready. The first start does real work, and the installer waits for it. Then open Darling Viewer. It opens on the fleet.
5. Add your first server in the viewer. darling.json is only a seed. The service reads it on its first start, so a server added to the file later is ignored (why).
6. The service log is in %ProgramData%\PerformanceMonitorDarling\logs.
7. The web dashboard is off after a script install. To turn it on, follow Turn it on. On a first install, .\install-darling.ps1 -WebDashboard writes a darling.json with the dashboard on and a web token. It does nothing when darling.json already exists.

Install Darling gives each step with the log line or screen that proves it worked. To upgrade, extract the new zip to a staging folder and run the upgrade-darling.ps1 in that folder. The script refuses to run from the install folder (Upgrade).

To remove the service, run uninstall-darling.ps1 from the install folder. The release also has PerformanceMonitorDarling-<version>.msi, an alternative to steps 1 to 3 (Installing with the MSI). For Linux and the web dashboard, read the Darling quick start. The Darling operator guide is the configuration reference.

Documentation

Page	What it covers
Choosing an edition	Lite, Darling, and Dashboard side by side
Features and screenshots	What you get, with screenshots
Lite guide	Install, upgrade, where Lite keeps its files, configuration, appearance, collectors
Lite Extended Events sessions	The sessions Lite creates on a monitored server, and how to remove them
Darling quick start	Install on Windows, Linux notes, web dashboard
Darling operator guide	Darling configuration, permissions, operations
Darling store sizing	Disk, RAM and vCPU for a store host, by number of servers
Back up, restore and move the store	Back up a Darling store, restore it, or move it to another machine
Darling guides	Install, viewer, web dashboard, MCP, day-to-day admin and command line reference
PostgreSQL target runbook	Point Darling at a PostgreSQL target, with a proof point at each step
Retention Held runbook	Clear a Retention Held alert
How collection works	A tour of the collection pipeline, for people who read the code
Documentation index	Every page in docs/, grouped by audience
Tabs	What each tab shows
Alerts and notifications	Alert types, channels, routes, email
Agent dispatch	Hand an alert to your own AI agent: levels, the brief and report, undo, the remediation login
Signed webhooks	Verify that a generic webhook post came from Darling
Agent job monitoring	Running SQL Agent jobs and jobs that run longer than expected
MCP server	Setup, the tool list and the Lite investigation tools for AI analysis
Authentication	Authentication types and credential profiles
Permissions	Grants for on-premises, Azure, and AWS RDS. The optional agent remediation login is in Agent dispatch
Platform notes	AWS RDS and Aurora configuration
Performance impact	Load on monitored servers, and local resources for Lite
Troubleshooting	Common problems for Lite and Darling
Building from source	Folder structure and build commands
Support and sponsorship	Commercial support tiers and sponsorship
Third-party components	Third-party components and their licenses
Changelog	Changes in each release

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.

Tier	Cost per year	Email response	Includes
Supported	$500	Within 2 business days	Guaranteed compatibility updates for new SQL Server versions, priority feature requests, a support agreement and invoices, unlimited instances
Priority	$2,500	By the next business day	Everything in Supported, plus a quarterly live Q&A session, early access to new features, and direct input on the roadmap

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

Sponsors

<table> <tr> <td><a href="https://signpath.io"><img src="docs/signpath_logo.svg" alt="SignPath" width="40"></a></td> <td>Free code signing on Windows provided by <a href="https://signpath.io">SignPath.io</a>, certificate by <a href="https://signpath.org">SignPath Foundation</a></td> </tr> </table>

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

Erik teaches database teams to work with AI agents on their own databases, in a one-day workshop and a video course. He also does SQL Server performance consulting.