Is there a way to check the intersection between my wishlist and the games shared with me over family sharing? In my case, both are very large.
If not through Steam, then maybe by visiting some website? Or using a browser plugin? Or an external program?
There is nothing in steam itself to do this and the Web API's do not have a way to retrieve a list of games in a wishlist. There are ways to get lists of games per user, but not wish list games. - Steam Web API - Steamworks Web API
The only way for this to be possible would be to parse the html source behind the user's wishlist page. There is a user script out there created by Eisenzange which will return a list of games in a simple text format. I have modified it slightly so that it will return each game on a new line.
Warning: These scripts are not guaranteed to work in the future as they make assumptions about the steam web page source. This is the only way to accomplish what you want at this time.
Retrieving the Wish List
// ==UserScript==
// @name Steam Wishlist to Text
// @namespace Eisenzange@steamgifts
// @include /^https?://steamcommunity\.com/.+/wishlist.*$/
// @version 1.0.0
// ==/UserScript==
var wishlistElements = document.getElementsByTagName("h4"),
wishlistNames = [],
i;
for (i=0;i<wishlistElements.length;i++)
{
wishlistNames.push(wishlistElements[i].innerHTML);
}
prompt("Wishlist:",wishlistNames.join("\r\n"));
If you aren't familiar with user scripts please check out this help page for an add-on called TamperMonkey. After installing tampermonkey and enabling the script, you should be able to visit your wishlist by visiting the following URL with YourUserName replaced with your actual username:
http://steamcommunity.com/id/YourUserName/wishlist
Note: Your user page doesn't necessarily have to use your user name. If you don't know how to find a profile URL, check out this video. It will show you in less than a minute.
When you visit the page a little prompt will come up (assuming your script is running) and it will give you a list of all the games. Copy and paste this into notepad or excel to see it all laid out.
Retrieving the Game List
Using http://steamcommunity.com/id/YourUserName/games/?tab=all does not return all of your games. Using steamcommunity.com/id/YourUserName/games/?xml=1 does return the list, but I could not get tampermonkey to read straight xml output. It was easier for me to write a quick program to do this. You could also use the Web API's mentioned above if you don't want to use my program. It runs on windows and only requires .NET Framework 4.0
Comparing the two lists
There are many tools out there you can use to compare lists. A simple google search gave me this tool which seems to work perfectly for what you need. I was able to copy and paste the results from those scripts into the two list fields on this site and it worked perfectly. Keep in mind that your original question wanted to see the games for multiple users and compare it to your wish list. This tool still works if you paste both your games and the other user's games into the first list, then paste the wish list games into the second list.
http://jura.wi.mit.edu/bioc/tools/compare.php
Results
Using the idea in Hagelt18's answer, I whipped together a quick tool to do all the hard work.
You can download the latest version here.
Requires .Net 4.6.
Please post any bugs here.
