My Tip: Stop Reading JSON, Start Seeing It. My Workflow Superpower is the Postman Visualizer.
The biggest bottleneck in API testing isn’t sending the request; it’s making sense of the response. We’ve all been there: scrolling through thousands of lines of a JSON array, trying to find that one value, or copy-pasting it into a converter just to show a colleague.
My one tip that I wish I’d known from day one is this: Use pm.visualizer.set() to transform raw API data into rich, interactive HTML reports inside the response window.
The Old Way: The JSON Eyeball Test
Imagine you hit an endpoint that returns a list of 100 users. Your goal is to quickly verify a few key things: Are all users ‘active’? Do their email formats look correct? Does anyone have a ‘null’ value for their last name?
The old way involved:
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Running the request.
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Getting back a massive, minified JSON blob.
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Prettifying it.
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Endless scrolling and using Ctrl+F to hunt for data.
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Giving up and writing complex pm.test() scripts just to check simple data integrity.
The “Aha!” Moment: Building a Custom Report on the Fly
The Postman Visualizer lets you use HTML, CSS, and JavaScript to render your response data. By adding a small snippet to your Tests script, you can build a custom view.
My Go-To Example: The “Data Sanity Check” Table
For that user list endpoint, I now have this in my Tests script:
“““
// 1. Define an HTML template with placeholders for our data.
// Handlebars templating is built-in!
const template = `
<style type="text/css">
table { font-family: sans-serif; border-collapse: collapse; width: 100%; }
th, td { border: 1px solid #dddddd; text-align: left; padding: 8px; }
tr:nth-child(even) { background-color: #f2f2f2; }
.status-active { color: green; font-weight: bold; }
.status-inactive { color: red; font-weight: bold; }
</style>
<h2>User Status Report ({{response.length}} users)</h2>
<table>
<tr>
<th>ID</th>
<th>Name</th>
<th>Email</th>
<th>Status</th>
</tr>
{{#each response}}
<tr>
<td>{{id}}</td>
<td>{{firstName}} {{lastName}}</td>
<td>{{email}}</td>
<td class="status-{{status}}">{{status}}</td>
</tr>
{{/each}}
</table>
`;
// 2. Get the JSON data from the response.
const responseData = pm.response.json();
// 3. Bind the data to the template and render it in the “Visualize” tab.
pm.visualizer.set(temp
late, { response: responseData });
“““
The Result is Pure Magic:
Now, when I hit “Send,” instead of a blob of JSON, I click the Visualize tab in the response pane and see a beautifully formatted HTML table.
Names and emails are perfectly aligned.
The user count is displayed in the header.
I used simple CSS to make active users green and inactive users red.
I can see in one second if there’s a data problem, without reading a single line of raw JSON.
Why This Is a Stand-Out Tip:
It’s Visual & Instant: It transforms abstract data into a concrete, easy-to-digest format. It provides an immediate “wow” factor that code-only tips can’t match.
It Goes Beyond Testing: This isn’t just for testers. I can screenshot these visual reports for product managers, create quick status dashboards, or demonstrate API functionality to clients without overwhelming them.
Infinite Possibilities: I started with tables, but now I embed Chart.js to plot data, Leaflet.js to show locations on a map, and render mermaid diagrams to show workflows—all powered by the API response data, directly inside Postman.
The Visualizer changed Postman from my API testing tool into my API data intelligence tool. It’s the ultimate workflow hack because it speeds up the slowest part of the process
Type.
Save to save the changes to your request.
It saves a lot of time for me, and now I don’t need to maintain separate k6 scripts anymore. The same Postman requests that my team already uses double as quick, lightweight load tests, saving setup time and catching regressions before they slip to prod.
Newman turns your Postman collections from a personal tool into a team superpower. Once you try it, you’ll never go back.