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.

See Network Reference if you want to browse features instead.

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 panel. 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. See 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. Open DevTools by pressing Control+Shift+J (Windows, Linux) or Command+Option+J (macOS). The Console panel opens.

    The Console

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

    DevTools docked to the bottom of the window

  3. Select the Network tab. The Network panel opens.

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

Right now the Network panel 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. Reload the page. 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. Selecting 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. Hover over a Waterfall to see a breakdown.

    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. See 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. You should see a new resource called getstarted.json. Selecting the Get Data button caused the page to request this file.

    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. Right-click the header of the Network Log table and choose Domain. The domain of each resource is now shown.

    Enable the Domain column

    Tip

    See the full URL of a resource by hovering over 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. Select the Throttling dropdown, which is set to Online by default.

    Enable throttling

  2. Choose Slow 3G.

    Select 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. This is helpful when you want to see 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 let you see how a page looked over time while it was loading.

  1. Select (Network settings) and select the Capture screenshots checkbox.

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

    Screenshots of the page load

  3. Select 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. Select (Network settings) again and deselect the Capture screenshots checkbox to close the Screenshots pane.

  5. Reload the page again.

Inspect the details of the resource

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

  1. Select getstarted.html. The Headers tab is shown. Use this tab to inspect HTTP headers.

    The Headers tab

  2. Select the Preview tab. A basic rendering of the HTML is shown.

    The Preview tab

    This tab 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. Select the Response tab. The HTML source code is shown.

    The Response tab

    Tip

    When a file is minified, selecting the Format (Format) button at the bottom of the Response tab re-formats the contents of the file for readability.

  4. Select the Timing tab. A breakdown of the network activity for this resource is shown.

    The Timing tab

  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. Select 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 tab opens. If the query was found in content, the Response tab opens.

    A search result highlighted in the Headers tab

  4. Close the Search pane and the Headers tab.

    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 enabled 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 other file matched the pattern they would also be 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

    See Filter requests by properties for the full list of filterable 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 see scripts, hold Control (Windows, Linux) or Command (macOS) and then choose JS.

    Show CSS and JS files only

  3. Choose All to remove the filters and see all resources again.

See Filter requests for other filtering workflows.

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. Reload 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 panel 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.
  • File bugs on this article using the 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.