Is it possible to have a link to raw content of file in Azure DevOps

Sure, here's the rests call needed:

GET https://feeds.dev.azure.com/{organization}/_apis/packaging/Feeds/{feedId}/packages/{packageId}?includeAllVersions={includeAllVersions}&includeUrls={includeUrls}&isListed={isListed}&isRelease={isRelease}&includeDeleted={includeDeleted}&includeDescription={includeDescription}&api-version=5.0-preview.1

https://docs.microsoft.com/en-us/rest/api/azure/devops/artifacts/artifact%20%20details/get%20package?view=azure-devops-rest-5.0#package

You can obtain the raw URL using chrome.

Turn on Developer tools and view the Network tab.

Navigate to view the required file in the DevOps portal (Content panel). Once the content view is visible check the network tab again and find the URL which starts with "Items?Path", this is json response which contains the required "url:" element.

Even after reading the existing answers, I still struggled with this a bit, so I wanted to leave a bit more of a thorough response.

As others have said, the pattern is (query split onto separate lines for ease of reading):

https://dev.azure.com/{{organization}}/{{project}}/_apis/sourceProviders/{{providerName}}/filecontents
  ?repository={{repository}}
  &path={{path}}
  &commitOrBranch={{commitOrBranch}}
  &api-version=5.0-preview.1

But how do you find the values for these variables? If you go into your Azure DevOps, choose Repos > Files from the left navigation, and select a particular file, your current url should look something like this:

https://dev.azure.com/{{organization}}/{{project}}/_git/{{repository}}?path=%2Fpackage.json

You should use those values for organization, project, and repository. For path, you'll see an HTTP encoded version of the unix file path. %2F is the HTTP encoding for /, so that path is actually just /package.json (a tool like Postman will do that encoding for you).

Commit or branch is pretty self explanatory; you either know what you want for this value or you should use master. I have "hard-coded" the api version in the above url because that's what the documentation currently points to.

For the last variable, you need providerName. In short, you should probably use TfsGit. I got this value from looking through the list of source providers and looking for one with a value of true for supportedCapabilities.queryFileContents.

However, if you just request this URL you'll get a "203 Non-Authoritative Information" response back because you still need to authenticate yourself. Referring again to the same documentation, it says to use Basic auth with any value for the username and a personal access token for the password. You can create a personal access token at https://dev.azure.com/{{organization}}/_usersSettings/tokens; ensure that it has the Token Administration - Read & Manage permission.

If you're unfamiliar with this sort of thing, again Postman is super helpful with getting these requests working before you get into the code.

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So if you have a repository with a src directory at the root, and you're trying to get the file contents of src/package.json, your URL should look something like:

https://dev.azure.com/{{organization}}/{{project}}/_apis/sourceProviders/TfsGit/filecontents?repository={{repository}}&commitOrBranch=master&api-version={{api-version}}&path=src%2Fpackage.json

And don't forget the basic auth!