Running a test from a CSV in Postman

March 18, 2023

I’ve previously written about running tests from JMeter. However, until this week, I hadn’t realised that Postman could do something similar. It turns out that you can give it a CSV, and then have it call the API for every line in that CSV. Thanks to Ash for the tip.

This actually takes a bit of messing about with the new version of postman, but here’s the steps.

Create a collection and request

Once you’ve created a collection, you can add a request, as you would normally:

Create collection

For the purpose of this illustration, I’m calling a local API that is heavily based on the default Web API that VS gives you for a new project; here’s what the request looks like:

Create request

I’ve basically changed the endpoint so that it accepts a parameter (a count of the number of weather forecasts to return). Notice that the URL looks like this:


The braces signify that we’re dealing with a variable. The next step is to create the variable.

Create a variable

There’s a couple of ways to do this - you can create global variables, or variables local to the collection:


For the purpose of this, we’ll make the variable local to the collection:

Collection variables

When you now run the request, you should see that it substitutes 1 for the {{count}} variable.

Run the collection

The next stage is to open the Collection Runner:

Run Collection Menu

That will give you this screen:

Run Collection

There’s a few options here, but the one that we’re interested in is Select File.

The file

The file is just a CSV file, but it needs a title row - this is mine:

first run,1
second run,2
third run,3
fourth run,2

For the purpose of this, the only thing that actually matters is the count; once you select this file, it will allow you to preview it:

Preview File

One thing that I found out is that if you can’t preview it, then you can’t use it either.

All that’s left is to run it.

Run the file

Once you select run, you’ll see a screen like this:


I don’t know what the limit to the file size is (or if there is one), but I tried it with hundreds of rows and it worked fine.

Profile picture

A blog about one man's journey through code… and some pictures of the Peak District

© Paul Michaels 2024