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.

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 .

    Figure 1

    The demo
    The demo

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

    Figure 2

    The Console
    The Console

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

    Figure 3

    DevTools docked to the bottom of the window
    DevTools docked to the bottom of the window

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

    Figure 4

    DevTools docked to the bottom of the window
    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.

    Figure 5

    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. Figure 6 shows the default columns:

    • Status. The HTTP status code for response.
    • Type. The resource type.
    • Initiator. The cause of the resource request. Clicking 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, click 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. Clicking the Get Data button caused the page to request this file.

    Figure 6

    A new resource in the Network Log
    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 select Domain. The domain of each resource is now shown.

    Figure 7

    Enabling the Domain column
    Enabling 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. Click the Throttling dropdown, which is set to Online by default.

    Figure 8

    Enabling throttling
    Enabling throttling

  2. Select Slow 3G.

    Figure 9

    Selecting Slow 3G
    Selecting Slow 3G

  3. Long-press Reload Reload and then select Empty Cache And Hard Reload.

    Figure 10

    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. Click Network settings and check Capture screenshots.

  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.

    Figure 11

    Screenshots of the page load
    Screenshots of the page load

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

    Figure 12

    The network activity that was happening during the first screenshot
    The network activity that was happening during the first screenshot

  4. Click Network settings again and uncheck Capture screenshots to close the Screenshots pane.

  5. Reload the page again.

Inspect the details of the resource

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

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

    Figure 13

    The Headers tab
    The Headers tab

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

    Figure 14

    The Preview tab
    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. Click the Response tab. The HTML source code is shown.

    Figure 15

    The Response tab
    The Response tab

    Tip

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

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

    Figure 16

    The Timing tab
    The Timing tab

  5. Click Close Close to view the Network Log again.

    Figure 17

    The Close button
    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 check if your resources are using reasonable cache policies.

  1. Click Search Search. The Search pane opens to the left of the Network log.

    Figure 18

    The Search pane
    The Search pane

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

    Figure 19

    Search results for Cache-Control
    Search results for Cache-Control

  3. Click a result to view which resource the result was found in. If you are looking at the details of the resource, click 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.

    Figure 20

    A search result highlighted in the Headers tab
    A search result highlighted in the Headers tab

  4. Close the Search pane and the Headers tab.

    Figure 21

    The Close buttons
    The Close buttons

Filter resources

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

Figure 22

The Filters toolbar
The Filters toolbar

The Filters toolbar should be enabled by default. If not:

  1. Click 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.

    Figure 23

    A string filter
    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.

    Figure 24

    A regular expression filter
    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.

    Figure 25

    A negative filter
    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.

    Figure 26

    A property filter
    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. Click CSS. All other file types are filtered out.

    Figure 27

    Showing CSS files only
    Showing CSS files only

  2. To also see scripts, hold Control (Windows) or Command (macOS) and then click JS.

    Figure 28

    Showing CSS and JS files only
    Showing CSS and JS files only

  3. Click 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. Press Control+Shift+P (Windows) or Command+Shift+P (macOS) to open the Command Menu.

    Figure 29

    The Command Menu
    The Command Menu

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

    Figure 30

    Show Request Blocking
    Show Request Blocking

  3. Click Add Pattern Add Pattern.

  4. Type main.css.

    Figure 31

    Blocking main.css
    Blocking main.css

  5. Click 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.

    Figure 32

    main.css has been blocked
    main.css has been blocked

  7. Uncheck 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!

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

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.