Meet Darling: Free, Headless Fleet Performance Monitoring for SQL Server
Watching one SQL Server is easy. Watching fifty is where monitoring vendors smell blood. The price is per server, per year, and it climbs every time your environment grows. Your reward for paying it: your performance data gets shipped to somebody else’s cloud, where you look at it through dashboards built by people who’ve never tuned a query in their lives.
Darling is my answer to that. It’s the new flagship edition of my free, open source SQL Server Performance Monitor. One SQL Server or five hundred, one product, no per-server tax, and your data never leaves your network.
What Darling is
Darling is a headless Windows service. You install it on one monitoring host, point it at your servers, and it collects around the clock. Nobody has to be logged in. Nothing gets installed on the monitored servers for its own storage.
It brings its own database. The installer bootstraps a managed PostgreSQL instance with TimescaleDB and runs it for you. There’s no repository server to stand up, no schema to deploy, no extra license to buy. Darling replaces the old SQL-Server-backed Dashboard edition, which needed a SQL Server of its own to store what it collected.
What it collects
36 collectors, the same shared library Lite uses: wait stats, query stats from the plan cache, Query Store, active query snapshots, blocking, deadlock graphs, execution plans, tempdb, memory grants and clerks, file IO latency, CPU, Agent jobs, server configuration, and more. Deltas are computed for you, so you see the work done between snapshots instead of staring at cumulative counters.
The store is yours
Everything lands in a PostgreSQL store you own. Not an API. Not an export wizard. Not a vendor data lake. Point any SQL client at it and query.
SELECT server_name, wait_type, sum(wait_time_ms) AS total_ms
FROM collect.wait_stats
WHERE collection_time >= now() – interval ‘1 day’
GROUP BY server_name, wait_type
ORDER BY total_ms DESC LIMIT 10;
Views are included for the common questions, but you’re not limited to them. It’s just tables. Join them however you want, feed Power BI, export to Excel.
Alerts without a babysitter
A real-time alert engine runs continuously: blocking, deadlocks, poison waits, long-running queries, tempdb space, long-running Agent jobs, high CPU, and servers that stop answering. Since Darling is headless, alerts go out by email and webhook (Slack, Teams, or any endpoint you point it at). Emails carry the query text, blocking chains, and deadlock XML. When a condition clears, it tells you that too. For the alerts that cry wolf, there are mute rules by server, metric, database, query, wait type, or job, with optional expiration.
An MCP server that can do things
Both editions ship a built-in MCP server, so an AI assistant like Claude can read your performance data directly. Darling’s can also write. An agent can build Custom Views, tune alert thresholds and mute rules, and onboard an entire fleet, all over MCP. Standing up monitoring for twenty servers is a sentence, not an afternoon.
Watch it from a browser
An optional read-only web dashboard shows the fleet from any browser, no install. It’s off by default and binds loopback-only until you deliberately expose it, token-gated and scoped to the network range you allow.
Custom Views and notebooks
This is the part the desktop app never had. Compose your own views over the collected data: pick the metrics, filters, grouping, and charts, or build notebook pages that mix charts with commentary. Make them by hand, or have an AI make them for you over MCP.
How to get it
Download the Darling zip, run the scripted install from an elevated prompt, and it bootstraps the Postgres store and starts the service. Add servers by pasting a list into the viewer, or over MCP. SQL Server 2016 through 2025, Azure SQL Managed Instance, Azure SQL Database, and AWS RDS are supported. Every release is signed.
There’s no paid version, and no locked features. If your compliance team needs a vendor agreement and a support contact on file before anything touches production, there’s a support subscription for that. The software is identical either way.
And Lite is not going anywhere
Lite, the desktop app with its local DuckDB store, is still here and still supported. Same 36 collectors, same shared brain. Darling is the answer for fleets and headless monitoring. Lite is the answer for the one machine you’re sitting in front of. Pick the one that matches your day.
Going Further
If this is the kind of SQL Server stuff you love learning about, you’ll love my training. Blog readers get 25% off the Everything Bundle — over 100 hours of performance tuning content. Need hands-on help? I offer consulting engagements from targeted investigations to ongoing retainers. Want a quick sanity check before committing to a full engagement? Schedule a call — no commitment required.