Getting Started - Replay HAR File

Follow this guide for a basic example of running a test that replays a HAR file. For our example we will record a simple HAR file that opens

Capture a HAR file

To capture our HAR file follow these steps:

  1. Open Chrome and enable the Developer Tools
  2. Select the Network tab
  3. Check “Preserve Log”
  4. Type in the URL bar (or whatever site you want to test)
  5. Wait until it finishes loading
  6. Right Click in the area where the network records are shown and select Save as HAR with content

Setup a Testable test

Start by signing up and creating a new test case using the Create Test button on the dashboard.

Enter the test case name (e.g. HAR Replay Demo) and press Next.


Select Replay HAR as the scenario type.

HAR Replay Scenario

Press the Add files… icon and upload the HAR file we captured earlier.

Basic Settings

Each virtual user will replay the HAR file with the exact delays between requests that were captured in the HAR file.

To try it out before configuring a load test click the Smoke Test button in the upper right and watch Testable execute the scenario 1 time as 1 user.

Click on the Configuration tab or press the Next button at the bottom to move to the next step.


Now that we have the scenario for our test case we need to define a few parameters before we can execute our test:

  1. Test Type: We select Load so that we can simulate multiple users as part of our test.
  2. Total Virtual Users: Number of users that will execute in parallel. Each user will replay the HAR file.</li>
  3. Test Length: Select Iterations to have each client execute the scenario a set number of times regardless of how long it takes. Choose Duration if you want each client to continue executing the scenario for a set amount of time (in minutes).
  4. Location(s): Choose the location in which to run your test and the test runner source that indicates which test runners to use in that location to run the load test (e.g. on the public shared grid).

Press Start Test and watch the results start to flow in. See the new configuration guide for full details of all configuration options.

For the sake of this example, let’s use the following parameters:

Test Configuration

View Results

Once the test starts executing, Testable will distribute the virtual users out to the selected test runners (e.g. Public Shared Grid in AWS N. Virginia) to simulate.

Test Results

The test runners execute 5 concurrent virtual users replaying our HAR file for 2 minute with a 10 second pause between iterations.

The results will include traces, performance metrics, logging, breakdown by URL, analysis, comparison against previous test runs, and more.

We also offer integration (Org Management -> Integration) with third party tools like New Relic. If you enable integration you can do more in depth analytics on your results there as well.

That’s it! Go ahead and try these same steps with your own scripts and feel free to contact us with any questions.