Azure Monitor OpenTelemetry Profiler for .NET

July 23, 2026 · View on GitHub

Description

The Azure Monitor OpenTelemetry Profiler captures detailed performance traces of your live .NET applications with minimal overhead. It helps you find slow code paths, high-CPU methods, and bottlenecks, then surfaces fixes through Code Optimizations in Application Insights. The profiler runs on a schedule (random sampling) and can also trigger on high CPU or memory.

Learn more: optix — Code Optimizations skills for Copilot · Profiler Agent Selection Guide · CPU & Memory usage monitoring

Get Started

Using this profiler is two phases: enable it (once), then analyze the traces it collects (ongoing). Enabling takes three steps.

Before you begin

You'll need:

.NET 8.0 or later
An Application Insights resource
Its connection string set as the APPLICATIONINSIGHTS_CONNECTION_STRING environment variable

Step 1 — Add the profiler package

🚀 On Azure App Service (Windows)? You can skip the package reference and code change entirely — see Codeless enablement below.

dotnet add package Azure.Monitor.OpenTelemetry.Profiler --prerelease

Step 2 — Enable the profiler in one line

Find the row that matches the telemetry SDK you already use, and add the highlighted call where you configure telemetry:

Your SDK	Add this call	Detailed walkthrough
Application Insights SDK for ASP.NET Core (`Microsoft.ApplicationInsights.AspNetCore`)	`AddApplicationInsightsTelemetry().AddAzureMonitorProfiler();`	Option A
Azure Monitor OpenTelemetry distro (`Azure.Monitor.OpenTelemetry.AspNetCore`)	`AddOpenTelemetry().UseAzureMonitor().AddAzureMonitorProfiler();`	Option B
Application Insights SDK for ASP.NET Core — classic 2.x (legacy)	Not supported — use Application Insights Profiler for ASP.NET Core instead	—

Step 3 — Run your app

dotnet run

Profiler traces appear in Application Insights after a few minutes. How to view them →

🤖 Prefer zero config? Let optix enable it for you. Install the Code Optimizations skills for Copilot CLI and run:
copilot "Help me enable the Application Insights Profiler"
See Enable the Profiler with optix.

Next: once traces are flowing, analyze them with optix to turn bottlenecks into concrete code fixes. Need more detail on enabling? Expand the walkthrough for your SDK below.

Option A: Application Insights SDK for ASP.NET Core (Experimental)

⚠️ Experimental — This integration is under active development. Please report any issues you encounter.

The current Microsoft.ApplicationInsights.AspNetCore SDK is an OpenTelemetry-based wrapper. Since it already configures OpenTelemetry internally, you can enable the profiler without adding Azure.Monitor.OpenTelemetry.AspNetCore or calling UseAzureMonitor().

Show setup walkthrough

Prerequisites

In addition to the Get Started prerequisites: your project must reference the current OpenTelemetry-based Microsoft.ApplicationInsights.AspNetCore SDK. The legacy classic 2.x release is not supported by this profiler — use Microsoft Application Insights Profiler for ASP.NET Core instead.

Walkthrough

Add NuGet Packages

dotnet add package Microsoft.ApplicationInsights.AspNetCore --version "3.*-*"
dotnet add package Azure.Monitor.OpenTelemetry.Profiler --prerelease

Or in your .csproj:

<ItemGroup>
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="[3.*-*, 4.0.0)" />
    <PackageReference Include="Azure.Monitor.OpenTelemetry.Profiler" Version="[1.*-*, 2.0.0)" />
</ItemGroup>

Enable the Profiler

Chain AddAzureMonitorProfiler() after AddApplicationInsightsTelemetry():

using Azure.Monitor.OpenTelemetry.Profiler;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddApplicationInsightsTelemetry().AddAzureMonitorProfiler();

var app = builder.Build();
app.Run();

Set up the connection string

Refer to the connection string section for all options. For local testing in PowerShell:
```
$env:APPLICATIONINSIGHTS_CONNECTION_STRING="InstrumentationKey=5d..."
```

Run & Verify

dotnet run

Look for profiler startup log messages like:

info: Azure.Monitor.OpenTelemetry.Profiler.ServiceProfilerAgentBootstrap[0]
    Starting application insights profiler with connection string: InstrumentationKey=5d…

After a few minutes, traces will appear in Application Insights — see how to view profiler data.

📖 Full example: aspnetcore-aisdk3

Option B: Azure Monitor OpenTelemetry Distro

Show setup walkthrough

Prerequisites

In addition to the Get Started prerequisites: this profiler works with the Azure Monitor OpenTelemetry distro.

Walkthrough

Assuming you are building an ASP.NET Core application:

Create a .NET Application (skip if you have one already)
```
dotnet new web
```

Add NuGet Packages

dotnet add package Azure.Monitor.OpenTelemetry.AspNetCore --prerelease
dotnet add package Azure.Monitor.OpenTelemetry.Profiler --prerelease

Tip: use floating versions to stay on the latest package:

<ItemGroup>
    <PackageReference Include="Azure.Monitor.OpenTelemetry.AspNetCore" Version="[1.*-*, 2.0.0)" />
    <PackageReference Include="Azure.Monitor.OpenTelemetry.Profiler" Version="[1.*-*, 2.0.0)" />
</ItemGroup>

Enable Application Insights with OpenTelemetry

Follow the instructions to enable Azure Monitor OpenTelemetry for .NET, then verify that data is flowing.

Enable Profiler

Append the call to AddAzureMonitorProfiler() in your code:

using Azure.Monitor.OpenTelemetry.AspNetCore;
// Import the Azure.Monitor.OpenTelemetry.Profiler namespace.
using Azure.Monitor.OpenTelemetry.Profiler;

...
builder.Services.AddOpenTelemetry()
        .UseAzureMonitor()
        .AddAzureMonitorProfiler();  // Add Azure Monitor Profiler
...

Run Your Application

Run your application and verify the profiler starts. Look for this in the log output:

info: Azure.Monitor.OpenTelemetry.Profiler.ServiceProfilerAgentBootstrap[0]
    Starting application insights profiler with connection string: InstrumentationKey=5d…
info: Azure.Monitor.OpenTelemetry.Profiler.Core.DumbTraceControl[0]
    Start writing trace file C:\Users\aaa\AppData\Local\Temp\SPTraces\...

View Profiler Data

After a few minutes, profiler traces will appear in Application Insights. Follow these instructions to view them.

📖 Full example: aspnetcore-webapi

Codeless enablement (no code change) — Beta

Running on Azure App Service? You can enable the profiler without changing your app's code, adding a NuGet package, or recompiling. A Kudu/SCM Site Extension (Windows) injects an ASP.NET Core IHostingStartup at process start, detects your app's telemetry stack (OpenTelemetry or classic Application Insights), and enables the matching profiler automatically. Enablement is fail-safe — if anything is incompatible, the profiler disables itself and your app keeps running.

All you need is an APPLICATIONINSIGHTS_CONNECTION_STRING app setting and a supported .NET telemetry stack.

Analyze Performance with optix

Enabling the profiler is a one-time step. The real, ongoing value is analysis — turning collected traces into fixes. optix (Code Optimizations skills for Copilot) automates that end to end:

Ingest — finds recent profiler traces on your Application Insights resource and downloads one.
Identify — extracts the hot path and ranks the top CPU and latency contributors.
Correlate — links hot frames to a specific operation or distributed trace, plus related errors and failed dependencies.
Recommend — maps hot frames to your source code and proposes concrete changes.
Verify — re-profiles after your change to confirm the bottleneck is gone.

Install the Code Optimizations skills for Copilot CLI, then ask:

copilot "Analyze my Application Insights Profiler traces and show me the top CPU bottlenecks"

No profiler data yet? optix will guide you back to enabling the profiler.

Troubleshooting

If profiles are not appearing in Application Insights:

Check logs — Enable debug logging to see the profiler pipeline activity:

{
  "Logging": {
    "LogLevel": {
      "Microsoft.ServiceProfiler": "Debug",
      "Microsoft.ApplicationInsights.Profiler": "Debug"
    }
  }
}

Verify connection string — Ensure your Application Insights connection string is configured correctly.
Check triggers — If using CPU or memory triggers, verify your thresholds are below observed usage levels. See CPU Usage Monitoring and Memory Usage Monitoring.
Entra authentication — If your Application Insights resource requires Entra (AAD) authentication, configure credentials accordingly. The profiler will log an error if authentication is missing.

If you're still experiencing issues, please open an issue with your environment details and relevant log output.

Examples

Learn more by following the examples:

Build Status

Pipeline	Status
Package
PR Build
Official Build

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Data Collection

The software may collect information about you and your use of the software and send it to Microsoft. Microsoft may use this information to provide services and improve our products and services. You may turn off the telemetry as described in the repository. There are also some features in the software that may enable you and Microsoft to collect data from users of your applications. If you use these features, you must comply with applicable law, including providing appropriate notices to users of your applications together with a copy of Microsoft’s privacy statement. Our privacy statement is located at https://go.microsoft.com/fwlink/?LinkID=824704. You can learn more about data collection and use in the help documentation and our privacy statement. Your use of the software operates as your consent to these practices.

Trademarks

This project may contain trademarks or logos for projects, products, or services. Authorized use of Microsoft trademarks or logos is subject to and must follow Microsoft's Trademark & Brand Guidelines. Use of Microsoft trademarks or logos in modified versions of this project must not cause confusion or imply Microsoft sponsorship. Any use of third-party trademarks or logos are subject to those third-party's policies.