Getting Fiddler to work with SharePoint Online

Something that I’ve always struggled with is getting Fiddler to provide me with REST API results for SharePoint online. These steps should help you.

Install and configure Fiddler

  1. First download and install Fiddler if you haven’t already. You can download fiddler at the following URL : Unfortunately you have to use an email address to be able to download it now.
  2. After first install of Fiddler, you will get an AppContainer Configuration dialog appear. Just click Cancel for now.
  3. Once Fiddler has opened, from the menu click Tools > Telerik Fiddler Options
  4. On the HTTPS tab ensure that Decrypt HTTPS traffic is selected
  5. Click OK. You will get a dialog asking if you should Trust the Fiddler Root certificate. It is fine to say Yes here.
  6. Say Yes to install the certificate.
  7. They really want to make sure, you are sure. Click Yes again.
  8. Fiddler’s root certificate has now been added to the Machine Root List.
  9. Close and Restart Fiddler.

Composing a REST URL for SharePoint Online.

First we need to log in to SharePoint online.

Now this is the point when I can never get it to work. I open IE/Edge, and instantly whenever I try to hit a https web page I get the following screen.

The trick here is to open Chrome and use that instead.

  1. Using Chrome, log in to your SharePoint online.
  2. In Fiddler, you should see in the left pane, it’s been capturing all your requests. Find a 200 result for your SharePoint site.
  3. In the right hand pane, take down the following information and store it in NotePad.
    1. FedAuth Cookie
    2. rtFA Cookie
  4. Above the right hand pane in Fiddler, one of the tabs is called Composer click on this tab.
  5. In the GET section put your REST API request E.g https://<YourOnlineName>
  6. In the section below enter the following:
    Accept: application/json;odata=verbose
    Content-Type: application/json;odata=verbose
  7. After cookie, you will want to put the rtFa=<rtFaCode>;FedAuth=<FedAuthCode>
  8. Click the Execute button at the top right of the screen. Once you have pressed it a call will be made and show up in the left hand pane. It’s easy to spot because the icon is for JSON.
  9. Double click on this entry and the right hand bottom pane, you will have your JSON response.

Performing Post Requests

There are a few more steps to complete to perform a post request, I’m going to walk you through the steps below. I already have a list called FiddlerList in my SharePoint online site. Currently it holds one item. (My site called Workflow as I was testing something with workflow before working on this post, this has nothing to do with the demo, hopefully it won’t confuse you)

  1. In Fiddler, from your previous composed GET request, first change the GET request to list all items currently in this list. My GET request is now https:// <YourOnlineName>‘FiddlerList’)/Items
  2. The results are show below. Take note of your type in the __metadata node. Mine is SP.Data.FiddlerListListItem
    you will need this later for adding an item. The type is normally SP.Data.<ListName>ListItem
  3. Now we need to create a POST request to the URI of /_api/contextinfo and then capture the FormDigestValue

  4. Now we have all the information required to create an item. Go back to the composed tab. Change the URI back to the way we had before to get the list items. https://<YourOnlineName&gt;‘FiddlerList’)/Items
  5. Add the X-RequestDigest: put in your FormDigestValue. Your page should look similar to below.
  6. Then in the bottom pane, the Request Body, put the following (Remember to change the type to match your list type).
    {'__metadata': {'type':'SP.Data.FiddlerListListItem'},
    'Title':'Created by Fiddler REST'
  7. Click Execute
  8. If all has worked well you should get a 201 Create Response back, and see the item created in your list.

Update API Request

To perform an update to the list item, first we need to know what the Item ID is. At the end of the 201 create JSON response I can see that the Item I created has the ID of 2.

  1. In my composer I have changed my URI to https://<YourOnlineName>‘FiddlerList’)/Items(2)
  2. In the top pane, I have set the content-length back to 0 and added IF-MATCH: * and X-HTTP-Method: PATCH this indicates that the post request is actually an update.
  3. Lastly in the bottom pane, Request Body, I have changed the Title.

    Note: Screen shot shows MERGE which is backwards compatible, should use newer command PATCH.
  4. After executing, I get a 204 response, and I can see the title has changed in my list.

Delete API Request

Lastly I’m going to delete my item.

  1. Change X-HTTP-Method to say DELETE instead of PATCH
  2. Remove the Request Body text.
  3. Click Execute, you will get a 200 response back.
  4. Your item has now been removed from the List.

The above should be enough to get you going. You can now use fiddler to test out your REST API calls.