Network logs

Network Logs (HAR)

BugBug automatically captures network activity during every test run — both local and cloud. This lets you inspect HTTP requests, responses, status codes, and timing to diagnose failures caused by API errors, slow endpoints, or unexpected redirects.

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How to access network logs

Network logs are available for every test run when they are enabled (by default) in Project Settings.

1. Go to the Runs history

2. Go to the failed test run and click Details

3. Click Download network logs (HAR) to download the file

💡 The download link is also available directly in the failed step when the test failed.

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What is a HAR file?

HAR (HTTP Archive) is a JSON-based standard that records all network requests made by the browser during a test. The file is compressed as a .zip archive containing a .har file inside.

Each entry in a HAR file includes:

• URL – the full request URL

• Method – GET, POST, PUT, etc.

• Status code – e.g. 200, 404, 500

• Request & response headers

• Request body (for POST/PUT requests)

• Response body

• Timing – how long each request took

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How to open a HAR file

After downloading and unzipping the archive, you can open the .har file in several ways:

Chrome DevTools

1. Open Chrome DevTools → Network tab

2. Drag and drop the .har file into the Network panel

Online viewers

• HAR Analyzer by Google — good for quick inspection

• HAR Viewer — detailed timeline view

Other tools

• Firefox DevTools (Network tab → Import)

• Charles Proxy, Fiddler, Insomnia — for deeper analysis

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Common debugging scenarios

API returning an error

Look for requests with status codes 4xx or 5xx. Check the response body for error messages from your backend.

Test failing on page load

Look for failed requests to JS bundles or critical API calls that happen right after navigation.

Assertion failing unexpectedly

Check if the data your test asserts against is fetched correctly — the response body will show what the server actually returned.

Slow or timing-out steps

Review the timing column to find requests that take unusually long and may be causing timeout failures.