Keyword grouping is one of the biggest trends in SEO at the moment. And it's not hard to see why.
Gone are the days where 1 page maps to 1 keyword.
Nowadays, 1 page can rank for 1000s of keywords. For example, look at the SERP for the keyword "invoicing software". You can see the top articles rank for 1000s of keywords.
Understanding how keywords semantically relate to each other allows one to target a broad group of keywords with one article.
But manually working these keyword groups or keyword clusters out is very time-consuming and difficult.
This is where keyword grouping tools come in. They help one programatically figure out which keywords belong in a group - either through Natural Language Processing (NLP) principles or with insight gleamed from real-time SERP analysis.
We tested out the best keyword grouping tools and here's what we found.
Keyword Grouping Software
1. KeyClusters
By the far the best keyword grouping tool we tested is KeyClusters.
This tool uses real-time SERP results to cluster keywords into groups based on the frequency of the same pages appearing in the top 10 results.
Put simply, if 3 or more of the same pages rank for a collection of keywords, then these keywords are grouped together.
KeyClusters makes the reasonable assumption that if 3 or more of the same pages can rank for a series of keywords, then you likely only need one page to target these keywords.
To avoid keywords appearing in duplicate groups the tool cross-references clusters to ensure keywords only appear in groups with the highest frequency of similar pages.
The tool works seamlessly with keyword reports from Ahrefs and SemRush, or you can upload a custom keyword file (for example, one for Google Search Console).
You can see the tool in action here.
To test the tool out we uploaded 1000 keyword file from Ahrefs on the topic "chicken recipes".
The KeyClusters dashboard is really intuitive to use, and I like that you can group keywords by device (mobile, desktop), geolocation, and any language.
The tool took about 3 minutes to cluster the 1000 keywords, which is pretty quick given that it uses real-time Google SERP data.
Here's a snapshot of the result. Pretty good if you ask me.
In terms of pricing, you get a 100 free credits when you sign up to KeyClusters. Pricing starts at $4.97 per 1000 keywords for their monthly subscription product, or you can use the tool on a PAYG basis for $9.99 per 1000 keywords. Credits never expire and you can cancel anytime.
2. SE Ranking
SE Ranking is an all-in-one SEO software similar to Ahrefs and SemRush. But unlike their competitors, they also have a sophisticated keyword grouping tool.
Like KeyClusters, SE Ranking uses SERP data to group keywords.
It's a fairly sophisticated tool that provides a lot of flexibility.
For example, you can choose the keyword grouping accuracy (i.e. the minimum number of URLs in the SERP to group keywords). Accuracy is defaulted to 3 URLs, but you can increase or decrease this.
You can also choose whether you want the tool to run a soft or hard analysis. The former allows you to groups keywords that have similar URLs to the primary keyword, but not to each other. This can result in broader keyword groups that are not that accurate.
Overall I was quite impressed with SE Ranking. I run a few tests with different accuracy and method settings, and the best result was with an accuracy setting of 3 and the hard method analysis that forces all keywords in a group to share URLs.
The tool also allows one to geo-locate the analysis and run it for any language.
So, what's the downside. Cost!
To use the SE Ranking keyword grouper you need a full SE Ranking subscription, which starts at around $25 per month. And then to use the keyword grouper, you have to pay for every keyword you group ($4 for 1000 queries, or $5 for 1000 queries with search volume).
If you only plan to use the keyword grouper functionality then this is pretty expensive!
3. Keyword Insights
Keyword Insights uses SERP data and NLP analysis to create keyword groups.
What makes Keyword Insights unique is its search intent feature.
In fact, when I first saw this I got really excited. Basically, Keyword Insights claims to use a machine learning algorithm to detect search intent and classify keywords into broad types - like long-form articles and product pages.
The tool also pulls data on the ranking URL for every keyword you give it, along with an analysis on where you rank.
How did the tool perform in my test?
I fed it 345 keywords on "chicken recipes" and here's its cluster analysis.
Overall, it looks like it did a great job. There were a few clusters that looked a little strange, but overall I think it got it right. I like how it separates keyword variations by row.
I was particularly impressed with the Hub-and-Spoke analysis it does. Basically, the tool attempts to define silos of articles that can be interlinked to each other.
Although this feature sounds quite promising, the Hubs-and-Spokes it found from my list were quite random and broad.
In terms of cost, Keyword Insights is on the pricey side. The cheapest plan is their Agency Elite subscription ($4.96 for 1000 keywords), but for this you need to commit to a 1,000,000 keywords a month (i.e. $4960 per month).
Most users will use their standard plans, which get as low as $6.67 / 1000 keywords. And there is a PAYG option too.
4. Keyword Cupid
As one of the first keyword grouping tools on the market, Keyword Cupid has a large community of users and a mature software.
The tool uses real-time SERP data to formulate its groups. It also claims to use machine learning to identify SERP patterns for groups, and has a confidence rating to measure how closely keywords are related.
It's not exactly clear how Keyword Cupid sets up their SERP analysis in terms of overlapping URLs and hard and soft relationships between URLS and keywords. But without looking under the hood, it's pretty clear that the algorithm returns very accurate results.
Keyword Cupid supports all the major keyword research tools, including Ahrefs and SemRush. They also have a feature called Bring Your Own Data (BYOD), which allows one to upload custom files.
Like the other tools mentioned above, you can set the geo-location and device for the SERP analysis.
The tool also offers quite a few features that other keyword groupers don't. For example, it groups keywords into topic silos, making it easier to define a site's hierarchy, and includes a SERP scraper and interactive mind-map visualisations.
Here's a typical output from Keyword Cupid.
As you can see the keyword clusters are very tight and accurate.
Here's what a silo looks like.
Again, the analysis here is very helpful, especially for those looking to create a full site plan and strategy on interlinking articles.
In terms of pricing, Keyword Cupid is a little on the pricey side. They offer three monthly subscription plans. Their basic plan costs $9.99 a month and only includes 500 keywords ($0.20 per keyword!). You can get up to 20k keywords a month on their largest plan, but this costs $149.99 per month ($0.07 per keyword).
There is no PAYG option, which I think is a major shortcoming for the tool, especially since most people use keyword groups sporadically and not on a monthly cadence.
5. Surfer SEO
Surfer SEO is an on-page content optimisation tool that we use extensively at Contentellect.
The tool comes with a content planner that is great for generating keyword groups. Like most of the insight generated in Surfer, the content planner uses NLP insight on keyword search intent to group keywords.
What I really like about Surfer's keyword planner is that you don't need to upload a list of keywords from a third party. The tool comes with a built-in keyword discovery tool that also pulls in search volume. Groups are then classified by search intent into broad categories like informational, local, customer investigation etc.
From the content planner it is very easy and quick to start working on an article within Surfer's content editor.
The whole process from keyword research, to grouping and then working on an article is seamless, and like other features in Surfer, the UI/UX is beautiful.
Here's what the content planner looks like. I gave the tool the seed keyword: "work anniversary".
As you can see, the content planner creates groups as individual tiles, and with a click of a button you can start writing an article for each tile.
So what's not to like?
Not much really. The one shortcoming is that the keywords are somewhat limited compared to tools like Ahrefs and SemRush, and because you can't upload your own keyword, you're totally dependent on whatever Surfer spits out.
Also, if you don't plan to use their content optimisation tool, then the cost for just the keyword planner is quite expensive.
See our full Surfer SEO review.
6. Cluster AI
Cluster AI was developed by Content Distribution.
Like KeyClusters, SE Ranking and Keyword Cupid, the tool uses real-time SERP data to formulate keyword groups. According to their documentation, Cluster AI looks at the number of common URLs on page one across a keyword list. If 3 or more URLs are shared between keywords, then they are grouped together.
You can read their documentation here.
Content Distribution have done an incredible job marketing this tool. Many SEOs are aware of the tool and quite a few have used it, including myself at one point.
Unfortunately, the product is nowhere as good as the marketing.
I found the tool to be very buggy (sometimes it stalls or just stops working), it has a terrible UI/UX and it's very expensive.
The keyword groups when it does work are quite good, but for the price and usability bugs I think you get much better value with the tools mentioned above.
7. SEO Scout (Free & Paid)
SEO Scout is a paid tool, but they offer a free keyword grouper as well. The tool uses an NLP methodology based on n-gram similarities.
The tool is very easy to use. You just upload a list of keywords, select a language and hit run. The results are presented in a similar way to Surfer SEO - i.e. as tiles, but you can export these to CSV.
Here are the results I got from my chicken recipe keyword list.
And here is what the CVS file looks like.
Overall I think the SEO Scout tool is a good free option, although I prefer ZenBrief (mentioned below). I've included it in my list of best SEO keyword grouping tools as it nicely compliments the broader SEO Scout keyword research software that is definitely worth checking out.
Free Keyword Grouping Tools
ZenBrief
As far as free keyword clustering tools go, ZenBrief is in my opinion the best.
Most free tools use a Lemma-based approach (i.e. grouping keywords based on their root similarities - cluster, clusters, clustering - all have root similarities and would therefore form a group).
ZenBrief uses an NLP methodology to understand the intent behind a keyword. This type of technique is a lot more accurate than Lemma-based clustering, although it's not as accurate as grouping methodologies that use SERP data.
The tool is very easy to use. You can upload as many as 30k keywords at one time (as long as the file is under 1MB). ZenBrief then analyses the keywords with its NLP algorithm to form groups.
Here's the result from my chicken recipe keywords.
You can also download the clusters to CSV, and the result looks as follows.
Overall I thought ZenBrief was quite good for a free tool.
Obviously, it has its limitations - it only supports English, there is no geolocation and you can't import or analyse search volume. Also, as an NLP-based keyword grouper, the accuracy is not tight enough to define article specific groups.
For example, many of the groups above have keywords that would actually need individual articles as the intent is quite different between each.
Umbrellum
Umbrellum is a keyword research and tracking tool developed by Wouter van der Meij, a freelance SEO consultant.
As part of the Umbrellum toolkit, Wouter has also built a free keyword grouping tool.
The tool allows you to enter a list of keywords (it's not clear how many you can enter, but I added 500 keywords and it worked just fine). It then uses a methodology called Levenshtein distancing to mathematically work out the distance between words and groups them into similar clusters.
As you can see below, it's put all keywords that mention wings into a group.
You can export the results to CSV, Excel or pdf - as well as print or copy them.
Overall, although it's a free SEO keyword grouper, I don't think the output is that helpful. The fact that a keyword shares a similar phrase doesn't mean it has the same semantic search or search intent relationship.
Also, if you're after a geolocated result or search volume, then you'll need to look elsewhere.
Keyword Clarity
Keyword Clarity's free keyword grouping tool is definitely worth checking out, especially if you like visual mind-maps or spider diagrams.
The tool works seamlessly with Google Search console or you can upload keywords from other sources. I uploaded my "chicken recipes" list from Ahrefs.
I couldn't work out what methodology the tool uses to cluster keywords, but I'm pretty sure it isn't NLP or SERP data. It most likely uses lemmatisation, which is an algorithmic process used to determine the intended meaning of a word.
The visualisation of keywords in a tree diagram is pretty cool. The tool splits phrases into individual keywords which are then linked by nodes that can be manipulated and reordered.
Here's a snapshot from my "chicken recipe" list.
For a free tool I was quite impressed with Keyword Clarity, especially if you're interested in silo'ing your content. But like Umbrellum, I think the actual clusters are prone to inaccuracies due to the lack of data from real-time ranking results.
MarketBold
MarketBold have a product called Keyword Grouper Pro that also does clustering for free.
All you have to do with Keyword Grouper Pro is insert a list of keywords and set the minimum group length (this is the number of terms the tool will consider to form a group).
You can also set words to exclude from the analysis. For example, in my case I uploaded my chicken recipe list, which understandably has those two words in most of the phrases. So I excluded them.
Again, it's not clear what algorithm the tool runs to group keywords, but I suspect it's similar to Keyword Clarity and Umbrellum.
My list processed very quickly. From the 1748 words it analysed, it formed 55 groups that had 3 or more terms in common.
The results are somewhat useful for those looking for a quick overview of how keywords relate to each other, but like the other free tools mentioned above, the output is not that helpful in defining what articles to write.
For example, in the salad group above, all of these keywords would probably need separate articles as the search intent is quite different between each.
Keyword Grouping FAQ
What is keyword grouping?
Keyword grouping is an SEO keyword research methodology that attempts to cluster keywords into topical groups or entities. Keyword grouping helps eliminate keyword cannibalization issues (i.e. creating multiple articles that target similar keywords, where one article would suffice). It also helps generate insight on keyword search intent, and how to cover a topic in its entirety to become a topical authority.
How does keyword grouping software work?
Most keyword grouping software use one of two main methodologies to group keywords. The most common method uses Natural Language Processing (NLP) to help identify and group keyword with similar intent. NLP results are usually good at identifying keywords at a silo-level, but not at an article-level. To get a more granular view of keyword groups, some tools use SERP data. Real-time SERP data helps identify overlapping URLs and keywords. Where keywords and URLs overlap consistently it is possible to group them based on their SERP relationships. This methodology generally provides a more accurate measure of a keyword group.
What is the best keyword grouping tool?
KeyClusters is the best keyword grouping tool. It uses real-time SERP data to analyse and group keywords into clusters that eliminate keyword cannibalisation risks. It's also one of the most affordable tools on the market.
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