Refinement Chips in Google Search
Google recently announced changes to how they handle vertical searches, result filters, and refinement chips (sometimes called pills).
In this article, I will give on overview over which filters I was able to reverse engineer. And how you can manipulate Google into showing them via URL parameters.
There is not actionable SEO advice in this article. Only continue reading if you care about how to trigger certain filters. Otherwise you will be severely bored.
Background
As part of Google’s attempt to comply with the DMA and other regulations in the European Union, the search giant recently published a blog post about their use of refinement chips.
Part of my job as Head of SEO at idealo is to follow such developments closely. So I used this opportunity to dive deeper into refinement chips.
Some of these (Images, News, etc.) have existed for over a decade. Others (Places, Products, etc.) were only added recently.
Not all of these are available globally. For example, product sites is currently only available in Germany, France, Czechia, and the UK. With a rollout to the rest of the EU planned in Q2.
Refinement Chips
For a typical Google search, we have two options to refine it. One row of tabs and one row of pills.
The tabs mainly launch vertical searches and the pills are mainly query refinements. Vertical searches are separate search experiences, often on a special media format with their own set of ranking criteria and SERP layout. Query refinements are just terms added to the original search term; but still regular web searches.
I say mainly because the lines have become blurry recently. For example, for hotel-related keywords, the pills can be pickers for dates and number of guests. While these terms are added to the query, they are also directly injected into the hotel widget.
While I do not like it, both the top and bottom row of filters are currently called refinement chips. Since this is the official wording used by Google in Google Search Central, I will use it here as well. Still, let’s keep the tabs and pills in mind to differentiate between them.
Now, what does all of this have to do with URL parameters?
URL Parameters in Google Search
Let’s start with some basics.
If we strip away all the tracking parameters, the clean URL of a Google search for Washington looks like this:
https://www.google.com/search?q=washingtonHere, q=washington is a parameter with the key q and the value washington. Anything that follows is based on such URL parameters.
If you are based in Germany but want to see the results someone in the USA is seeing, you can add &gl=us to set the location to US and &hl=en to set the language to English. That gives you:
https://www.google.com/search?q=washington&gl=us&hl=enThe reverse would be for someone in the US to add &gl=de&hl=de to see German search results:
https://www.google.de/search?q=washington&gl=de&hl=deDisclaimer: to fully get the experience of someone located in a certain country, you will either need to manipulate the geo coordinates your browser is sending or use a VPN. But that is not the focus of this article.
Back to URL parameters. Now that we know how to manipulate Google search results with URL parameters, let’s connect that to vertical searches and refinement chips.
Vertical Searches
Via the &tbm parameter it has always been possible to trigger the vertical searches for images, videos, etc.
For example &tbm=isch forces Google to show an image search.
https://www.google.com/search?q=washington&tbm=ischOther valid &tbm values are
- &tbm=isch Images (Link)
- &tbm=shop Shopping (Link)
- &tbm=nws News (Link)
- &tbm=bks Books (Link)
- &tbm=vid Videos (Link)
Chips
Google recently introduced a new parameter with a lot more options: &udm
Just like &gl, &hl, and &tbm, we can inject them into the URL. For example &udm=18 gives us forum results:
https://www.google.com/search?q=washington&udm=18Here are all the parameters we were able to reverse engineer at idealo:
- &udm=1 Places (Link)
- &udm=2 Images (Link)
- &udm=3 Products (Link)
- &udm=5 Lodging (Link)
- &udm=6 Learn (Link)
- &udm=8 Jobs (Link)
- &udm=9 Product sites (Link)
- &udm=10 Job sites (Link)
- &udm=11 Places sites (Link)
- &udm=13 Airline options (Link)
- &udm=14 Web: 10 blue links (Link)
- &udm=18 Forums (Link)
- &udm=31 Flight sites (Link)
- &udm=34 Transportation sites (Link)
Please note: many of these do not work everywhere, since they are tied to Google’s DMA efforts in Europe. And many will only work for certain keywords. Where possible, I linked US examples. My fallbacks are UK and Germany (English) in that order.
There are a few more that simply redirect:
- &udm=7 redirects to &tbm=vid (Videos)
- &udm=12 redirects to &tbm=nws (News)
- &udm=28 redirects to &tbm=shop (Shopping)
Then there are some that do not seem to do anything: 0, 4, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 29, 30, 35, 36. They are not removed from the URL but they do not show anything special either.
Any value above 36 gets removed from the URL. So they seem to truly not exist.
Then there is a weird one: &udm=24 (Link). It does something. But I am not sure what. In fact, I have not found a single keyword where this parameter returned any result. The best we ever got was triggering one Google Shopping ad above an otherwise empty SERP
Recent Developments
Until at least February 2024, &udm=2 was redirected to &tbm=isch (Images). Google recently reversed this behavior. &tbm=isch is now redirected to &udm=2.
&udm=3 used to redirect to &tbm=shop (Shopping). It no longer redirects. Instead, it is now the URL parameter for Products. Similar to Shopping but not equal.
I assume Google will migrate the remaining &tbm= options to &udm= as well.
Why care?
Officially, Google is only testing some of these new refinement chips. I have been tracking them since Q4 last year and even in the first rollout countries (like Germany) they disappear and reappear all the time.
Being able to force Google to show, for example, forum results for a keyword where Google would normally not suggest forum results can be interesting for all kinds of SEO-related activities.
In my case, being able to see these features whenever I want, makes it simpler to evaluate if they are truly DMA compliant.
