Cloud-based Load Testing REST APIs are here

Jimson Chalissery [MSFT]

Many of you are looking at being more agile when it comes to testing, and with increased focus on automation, there are quite a few who wants to integrate Load Testing as a regular test practice. This could be either for those validating performance of their nightly/weekly builds or those that just does not want to wait for big milestone releases to validate performance but instead do it as part of a more frequent Automated Testing. This is more of a “culture” thing and one that is catching up fast.

That is why we now have REST APIs for Cloud-based Load Testing with Visual Studio Online.

The Cloud-based Load Testing (CLT) REST APIs give you the ability to execute Load tests from the Cloud in an automated manner, that can be integrated either as part of your Continuous Integration/Deployment pipeline or Test Automation.

Here’s a list of what you can do with these new APIs:

  • Start/Stop a Load Test Run
  • Get Load Test Results  – the set of KPIs groups that you are used to – Performance, Throughput, Application
  • Get Messages from the service during a run
  • Get Exceptions, if any, from the service during a run
  • Get Counter instances and Samples for a Load Test run
  • Get Application Counters for Apps configured with your load test
  • Get list of all past Load test Runs – filtered by requester, date, status etc..


Some callouts

  • For using the REST APIs, you’ll need to enable alternate credentials, and use that for authentication
  • Add “vsclt” to your account name to get redirected to the Cloud-based Load Test (CLT) service within If your account is, then when using APIs, please specify this as
  • To get started you can refer to the API sample here (Creating a load test) & here (Importing results) that demonstrates some of the APIs
  • You need to include ?api-version=1.0-preview.1 in your API calls. Please follow the instructions given here. With effect from 26th Nov 2014, addition of version to the API is mandatory


How to use the APIs

The following steps are essential to be successful with these APIs. These are demonstrated in the sample linked above.

  1. Create a valid load test project via Visual Studio. And use the files from this project for the load test.
  2. Create a location to upload the file(s). This location is a drop folder on Azure Blob and is below referred to as “TestDrop”.
  3. Upload the loadtest file and any other files required for the run, this includes the webtest files, settings file, etc. to this location or “TestDrop”
  4. Create a Test Run using the Testdrop from the previous step as all the files required for a run are now available at the drop location
  5. Start the run
  6. Once finished, download the results to your local machine. This will be a gzip file. Uncompress it to get the results file
  7. Use Visual Studio to view the downloaded results

API Documentation

You can find the detailed API documentation here.

Samples are available at the MSDN Gallery (here (Creating a load test) & here (Importing results)) that demonstrates the APIs.

Please share any and all feedback on the APIs. If you have suggestions for improving it further, we’re all ears. If you run into any issues, you can reach out to us at


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