Binary file upload in Postman - Build an Automation Script

Upload a binary file using Postman

Preconditions (3)

Step 1: Open Postman and create a new POST request

Step 2: Enter the API endpoint URL in the request URL field

Step 3: Go to the 'Body' tab

Step 4: Select 'binary' radio button

Step 5: Click 'Select File' and choose the binary file (image.png) from local machine

Step 6: Click 'Send' button to submit the request

✅ Expected Result: The API responds with a success status code (e.g., 200 or 201) and a confirmation message indicating the file was uploaded successfully

Automation Requirements - Postman test scripts

Assertions Needed:

Response status code is 200 or 201

Response body contains confirmation message or success indicator

Best Practices:

Use environment variables for API endpoint URL

Validate response status and body in test scripts

Keep binary file path configurable

Use descriptive test names and comments

Automated Solution

Postman

pm.test('Status code is 200 or 201', function () {
    pm.expect(pm.response.code).to.be.oneOf([200, 201]);
});

pm.test('Response contains success message', function () {
    const jsonData = pm.response.json();
    pm.expect(jsonData.message || jsonData.status).to.match(/success|uploaded/i);
});

The first test checks that the response status code is either 200 or 201, which means the upload was successful.
The second test parses the JSON response body and verifies it contains a success message or status.
Using pm.expect ensures clear assertion failures if the API does not behave as expected.
These tests run automatically after sending the binary file upload request in Postman.

Common Mistakes - 4 Pitfalls

{'mistake': "Not selecting 'binary' option in the Body tab", 'why_bad': 'The file will not be sent as binary data, causing the API to reject or misinterpret the upload', 'correct_approach': "Always select the 'binary' radio button before choosing the file to upload"}

Hardcoding API endpoint URL in multiple requests

Not validating response status code

Assuming response body is always JSON without checking

Bonus Challenge

Now add data-driven testing with 3 different binary files (e.g., image.png, document.pdf, audio.mp3) to upload

Show Hint