Inspect network activity in Microsoft Edge DevTools

This is a hands-on tutorial of some of the most commonly-used DevTools features related to inspecting network activity for a page.

If you want to browse features, navigate to Network Reference.

When to use the Network panel

In general, use the Network panel when you need to make sure that resources are being downloaded or uploaded as expected. The most common use cases for the Network panel are:

  • Making sure that resources are actually being uploaded or downloaded at all.
  • Inspecting the properties of an individual resource, such as the HTTP headers, content, size, and so on.

If you are looking for ways to improve page load performance, do not start with the Network tool. There are many types of load performance issues that are not related to network activity. Start with the Audits panel because it gives you targeted suggestions on how to improve your page. Navigate to Optimize Website Speed.

Open the Network panel

To get the most out of this tutorial, open up the demo and try out the features on the demo page.

  1. Open the Get Started Demo.

    The demo

  2. To Open DevTools, select Control+Shift+J (Windows, Linux) or Command+Option+J (macOS). The Console tool opens.

    The Console

    You may prefer to dock DevTools to the bottom of your window.

    DevTools docked to the bottom of the window

  3. Open the Network tool.

    Console tool in the DevTools docked to the bottom of the window

Right now the Network tool is empty. DevTools only logs network activity after you open it and no network activity has occurred since you opened DevTools.

Log network activity

To view the network activity that a page causes:

  1. Refresh the webpage. The Network panel logs all network activity in the Network Log.

    The Network Log

    Each row of the Network Log represents a resource. By default the resources are listed chronologically. The top resource is usually the main HTML document. The bottom resource is whatever was requested last.

    Each column represents information about a resource. In the previous figure the default columns are displayed.

    • Status. The HTTP status code for response.
    • Type. The resource type.
    • Initiator. The cause of the resource request. CHoosing a link in the Initiator column takes you to the source code that caused the request.
    • Time. The duration of the request.
    • Waterfall. A graphical representation of the different stages of the request. To display a breakdown, hover on a Waterfall.

    Note

    The graph above the Network Log is called the Overview. You will not use the Overview graph in this tutorial, so you may hide it. Navigate to Hide the Overview pane.

  2. After you open DevTools, it records network activity in the Network Log.
    To demonstrate this, first look at the bottom of the Network Log and make a mental note of the last activity.

  3. Now, select the Get Data button in the demo.

  4. Look at the bottom of the Network Log again. A new resource named getstarted.json is displayed. To cause the webpage to request the file, choose the Get Data button.

    A new resource in the Network Log

Show more information

The columns of the Network Log are configurable. You may hide columns that you are not using.
There are also many columns that are hidden by default which you may find useful.

  1. Hover on the header of the Network Log table, open the contextual menu (right-click), and choose Domain. The domain of each resource is now shown.

    Enable the Domain column

    Tip

    To review the full URL of a resource, hover on the cell in the Name column.

Simulate a slower network connection

The network connection of the computer that you use to build sites is probably faster than the network connections of the mobile devices of your users. By throttling the page, you get a better idea of how long a page takes to load on a mobile device.

  1. Choose the Throttling dropdown, which is set to Online by default.

    Enable throttling

  2. Choose Slow 3G.

    Choose Slow 3G

  3. Long-press Reload (Reload) and then choose Empty Cache And Hard Reload.

    Empty Cache And Hard Reload

    On repeat visits, the browser usually serves some files from the cache, which speeds up the page load. Empty Cache And Hard Reload forces the browser to go the network for all resources. Use it to display how a first-time visitor experiences a page load.

    Note

    The Empty Cache And Hard Reload workflow is only available when DevTools is open.

Capture screenshots

Screenshots display how a webpage looks over time while it loads.

  1. Choose (Network settings) and turn on the Capture screenshots checkbox.

  2. Refresh the page again using the Empty Cache And Hard Reload workflow. Navigate to Simulate a slower connection if you need a reminder on how to do this.
    The Screenshots panel provides thumbnails of how the page looked at various points during the loading process.

    Screenshots of the page load

  3. Choose the first thumbnail. DevTools shows you what network activity was occurring at that moment in time.

    The network activity that was happening during the first screenshot

  4. Choose (Network settings) again and turn off the Capture screenshots checkbox to close the Screenshots pane.

  5. Refresh the page again.

Inspect the details of the resource

Choose a resource to learn more information about it. Try it now:

  1. Choose getstarted.html. The Headers panel is shown. Use this panel to inspect HTTP headers.

    The Headers panel

  2. Choose the Preview panel. A basic rendering of the HTML is shown.

    The Preview panel

    The panel is helpful when an API returns an error code in HTML. You may find it easier to read the rendered HTML than the HTML source code, or when you inspect images.

  3. Choose the Response panel. The HTML source code is shown.

    The Response panel

    Tip

    When a file is minified, choose the Format (Format) button at the bottom of the Response panel to re-format the contents of the file for readability.

  4. Choose the Timing panel. A breakdown of the network activity for the resource is displayed.

    The Timing panel

  5. Choose Close (Close) to view the Network Log again.

    The Close button

Search network headers and responses

Use the Search pane when you need to search the HTTP headers and responses of all resources for a certain string or regular expression.

For example, suppose you want to verify that your resources are using reasonable cache policies.

  1. Choose Search (Search). The Search pane opens to the left of the Network log.

    The Search pane

  2. Type Cache-Control and select Enter. The Search pane lists all instances of Cache-Control that it finds in resource headers or content.

    Search results for Cache-Control

  3. Choose a result to view the resource in which the result was found. If you are looking at the details of the resource, select a result to go directly to it. For example, if the query was found in a header, the Headers panel opens. If the query was found in content, the Response panel opens.

    A search result highlighted in the Headers panel

  4. Close the Search pane and the Headers panel.

    The Close buttons

Filter resources

DevTools provides numerous workflows for filtering out resources that are not relevant to the task at hand.

The Filters toolbar

The Filters toolbar should be turned on by default. If not:

  1. Choose Filter (Filter) to show it.

Filter by string, regular expression, or property

The Filter text box supports many different types of filtering.

  1. Type png into the Filter text box. Only the files that contain the text png are shown. In this case the only files that match the filter are the PNG images.

    A string filter

  2. Type /.*\.[cj]s+$/. DevTools filters out any resource with a filename that does not end with a j or a c followed by 1 or more s characters.

    A regular expression filter

  3. Type -main.css. DevTools filters out main.css. If any file matches the pattern, tit is also filtered out.

    A negative filter

  4. Type domain:cdn.glitch.com into the Filter text box. DevTools filters out any resource with a URL that does not match this domain.

    A property filter

    For the full list of filterable properties, navigate to Filter requests by properties.

  5. Clear the Filter text box of any text.

Filter by resource type

To focus in on a certain type of file, such as stylesheets:

  1. Choose CSS. All other file types are filtered out.

    Show CSS files only

  2. To also display scripts, select and hold Control (Windows, Linux) or Command (macOS) and then choose JS.

    Show CSS and JS files only

  3. To remove the filters and display all resources again, choose All.

For other filtering workflows, navigate to Filter requests.

Block requests

How does a page look and behave when some of the page resources are not available? Does it fail completely, or is it still somewhat functional? Block requests to find out:

  1. Select Control+Shift+P (Windows, Linux) or Command+Shift+P (macOS) to open the Command Menu.

    The Command Menu

  2. Type block, choose Show Request Blocking, and select Enter.

    Show Request Blocking

  3. Choose Add Pattern (Add Pattern).

  4. Type main.css.

    Blocking main.css

  5. Choose Add.

  6. Refresh the page. As expected, the styling of the page is slightly messed up because the main stylesheet has been blocked.

    Note

    The main.css row in the Network Log. The red text means that the resource was blocked.

    main.css has been blocked

  7. Deselect the Enable request blocking checkbox.

Conclusion

Congratulations, you have completed the tutorial. You now know how to use the Network tool in the Microsoft Edge DevTools!

Navigate to the Network Reference to discover more DevTools features related to inspecting network activity.

Getting in touch with the Microsoft Edge DevTools team

Use the following options to discuss the new features and changes in the post, or anything else related to DevTools.

  • Send your feedback using the Send Feedback icon or select Alt+Shift+I (Windows, Linux) or Option+Shift+I (macOS) in DevTools.
  • Tweet at @EdgeDevTools.
  • Submit a suggestion to The Web We Want.
  • To file bugs about this article, use the following Feedback section.

The Send Feedback icon in the Microsoft Edge DevTools

Note

Portions of this page are modifications based on work created and shared by Google and used according to terms described in the Creative Commons Attribution 4.0 International License.
The original page is found here and is authored by Kayce Basques (Technical Writer, Chrome DevTools & Lighthouse).

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.