8 Free and Paid Keyword Clustering Tools (Expert Reviewed)

I’m a “work smarter, not harder” kind of writer. I have a massive to-do list, so I always want to spend the least amount of time possible to produce the best results.

To that end, I think keyword clustering is an important SEO technique to implement. By targeting multiple keywords in one piece of content, you maximize its impact without significantly increasing your workload.

And with a keyword clustering tool to do the heavy lifting, you can simplify your workflow even further.

I’ve tested out several free and paid keyword clustering tools that can help you build your content strategy from the ground up. I’ll share my honest reviews so you can choose the best solution for you and start working smarter, too.

Best Paid Keyword Clustering and Grouping Tools

Paid keyword clustering tools tend to provide a higher degree of accuracy, so your keyword grouping efforts are more likely to pay off. Particularly if you choose a tool that goes beyond keyword grouping and can help with other aspects of SEO, I think this is a worthwhile investment.

Semrush

Semrush is my preferred tool for keyword research, including keyword clustering. It offers a full suite of SEO and digital marketing features.

Semrush uses live SERP analysis, keyword data, and search intent to create its keyword groups. It’s easy to create a seamless workflow with the variety of keyword research tools it provides, and it offers flexibility in how you approach keyword clustering, too.

AI-Powered Keyword Clustering in Semrush

In order to start keyword clustering, you first need a keyword list. If you don’t have one already, Semrush can build one for you, which is a huge time saver.

The Keyword Strategy Builder can take one or more seed keywords and use AI to create a comprehensive keyword list.

Semrush then analyzes SERPs, finds subtopics, and organizes relevant keywords into clusters. The result is a handy chart that visualizes your keyword groups, which I really like.

If you hover over one of the clusters, you’ll see additional keywords for that group.

Below this chart, there’s a breakdown of the different pages Semrush recommends creating around your topics. You can filter those pages based on ranking potential, keyword intent, or traffic potential.

For each topic, Semrush suggests a pillar page and subpages with a keyword group to target.

There’s a ton of data available here, so I recommend checking out Semrush’s full walkthrough of the Keyword Strategy Builder.

Manual Keyword Clustering in Semrush

If you want more control over your keyword clusters, you can create your keyword list manually.

When you open the Keyword Strategy Builder, you’ll see an option to “create a regular list with your own keywords.”

Once you’ve named your list, you can add keywords to it from other tools in Semrush, like the Keyword Overview and Keyword Magic tools.

When you’re done building your list, click on “Cluster this list” in the top right corner of the Keyword Strategy Builder.

The result will be a list of pages and subpages, each with their own keyword groups, similar to what you get when having Semrush build your list for you.

Exporting Your Keyword Clusters from Semrush

Being able to share or export your keyword clusters is important if you’re working with a team of writers. Semrush gives you the option to share your keyword lists with other users or export it in a spreadsheet-compatible format.

You can choose if you want to export all of the data, or if you want to select specific pages and keywords.

Semrush Pricing

The Semrush Pro plan costs $117.30 per month when billed annually. You can try it out for free to get a feel for it before you commit.

Surfer SEO

Surfer SEO provides several features to create and optimize content for search. In addition to keyword research, topical maps, and rank tracking, it also offers AI content generation.

It can also create keyword groups based on search intent, keyword difficulty, and keyword volume. It’s very user friendly and simpler than Semrush if you find all the data in the Keyword Strategy Builder overwhelming.

You can read our comprehensive Surfer SEO vs Semrush guide here.

Keyword Clustering in Surfer SEO

To create keyword clusters with Surfer SEO, you don’t need to have a keyword list prepared ahead of time. Just open the Tools section and type in your seed keyword.

Surfer SEO will return your keyword clusters in neatly organized tiles.

There are a few filters you can use to narrow down your results:

• Intent: Helpful for creating content to target users at different stages of the customer journey
• Keywords: View groups based on how many keywords they include
• Search Volume: Set a minimum and/or maximum monthly aggregate search volume to find the groups with the best traffic potential

Additionally, you can view more details for each individual keyword cluster, such as monthly search volume for each keyword, monthly traffic for the whole group, and aggregate and individual keyword difficulties.

This data is useful for making decisions on which keyword clusters to prioritize.

Exporting Keyword Clusters from Surfer SEO

Exporting your keyword clusters from Surfer SEO is very simple. There’s an export button at the top of the screen that will download a CSV file to your computer.

The sheet is fairly readable and includes all the data in for each individual cluster.

Surfer SEO Pricing

Surfer SEO’s Essential plan is $79 per month when billed annually. There’s a seven day money back guarantee.

Keyword Cupid

Keyword Cupid has some unique features and settings that make it an interesting solution for keyword grouping.

When creating keyword clusters, Keyword Cupid considers search intent to group related keywords. You can also import additional data if you want it to factor in search volume or keyword difficulty.

Keyword Clustering in Keyword Cupid

The Keyword Cupid user experience is pretty straightforward, but not the smoothest.

You start by creating a project, then running a report for that project. There are several features and settings available:

• BYOD (Bring Your Own Data): Upload data like search volume and keyword difficulty from another source, like Semrush
• Report Customization: Choose if you want to use SERP analysis for a specific location or device type
• SERP Spy: Scrape the top SERPs for your keyword and analyze the content for recommended word count, number of headings, and other elements

In the interest of keeping things simple, I didn’t upload any additional data when I tested it.

I did need a keyword list, however. Keyword Cupid doesn’t include any tools for generating one like Semrush or Surfer, so I exported my keyword list from Semrush.

All I had to do was paste the list into the report.

This is the point where I encountered my biggest problem with Keyword Cupid. It took over ten minutes to generate keyword clusters. That time may not make much of a difference, but I expected a higher quality user experience from a paid tool.

The way Keyword Cupid returns its keyword clusters is unique as well. It presents a flow chart with expandable keyword groups.

The keyword clusters it produced were decent quality. I found the chart a little unwieldy to navigate, but I appreciate the visual representation of the keyword groups.

Exporting Keyword Clusters from Keyword Cupid

Keyword Cupid lets you download your keyword clusters as a CSV file at the click of a button. Its CSV format is actually my favorite of all the tools I tried.

It’s very clear and easy to read. I prefer it to the chart Keyword Cupid provides.

Keyword Cupid Pricing

Keyword Cupid pricing starts at $9.99 per month, which allows you to cluster 500 keywords per month. I would recommend upgrading to the Freelancer plan for $49.99 per month, increasing the keyword limit to 5,000 per month.

KeyClusters

KeyClusters is a dedicated keyword clustering tool, which has its pros and cons. On the upside, it has settings that you won’t find in a more generalized platform.

The drawback is that you’ll need other SEO tools to access a full suite of features. For starters, KeyClusters doesn’t include any features to help you build a keyword list. You have to upload a list from Semrush or another platform.

Keyword Clustering in KeyClusters

I used part of my “paddleboarding techniques” keyword list from Semrush to test out KeyClusters.

When setting up my project, I could control the sensitivity of KeyClusters’ analysis and grouping. This number represents how many SERPs the same page must appear on for KeyClusters to group the keywords together.

For example, if the same article is in the top results for “prone paddleboarding techniques”, “sup paddleboarding techniques”, and “how to hold a paddleboard paddle”, KeyClusters will group those terms together.

You can also customize your clusters based on location and device.

Once KeyClusters is done building your keyword groups, you can download a CSV that will include a primary keyword, aggregate keyword volume, keyword difficulty, and keyword variations for each cluster.

There’s no user interface with charts or additional data on your keywords.

The functionality of KeyClusters is solid, and it’s easy to use. However, I still needed Semrush to create my keyword list, and Semrush does everything KeyClusters does, plus a lot more.

KeyClusters Pricing

KeyClusters doesn’t require a monthly subscription, so you can pay as you go. Pricing starts at $9 for 1,000 keywords.

Free Keyword Clustering Tools

If you want to dive into keyword clustering but don’t have the budget for a paid tool, there are several free options. As with most things, you often get what you pay for, so be aware of possible inaccuracies and strict usage limits when relying on these tools.

SEO Scout

SEO Scout offers both free and paid SEO tools, including features for split testing, keyword research, rank tracking, keyword cannibalization tracking, and link analysis. One of the free tools in its arsenal is its keyword clustering tool.

Keyword Clustering in SEO Scout

You’ll need to come to SEO Scout with a keyword list. The tool is extremely easy to use — just paste in your list and add a primary keyword.

SEO Scout returns your keyword clusters in neat little boxes that are clearly labeled.

You can also export your keyword clusters as a CSV file, which will have a column for the name of the keyword group and a column for keywords.

I feel that SEO Scout’s results weren’t as useful as those from the paid tools I tried. While Semrush and even KeyClusters prioritized the keywords with the most potential, SEO Scout seemed to get really hung up on some of the less promising keywords in my list.

SEO Scout Keyword Clustering Usage Limits

I’ve found no usage limits for SEO Scout’s keyword clustering tool. During my testing, I pasted in a list of almost 1,200 keywords and didn’t encounter any restrictions.

Zenbrief

Zenbrief is an SEO content optimization tool. Its primary features are brief generation, AI content optimization, and content auditing tools, but it also offers a free keyword clustering tool.

Keyword Clustering in Zenbrief

Zenbrief’s keyword clustering tool is straightforward to use. Just paste in your keyword list.

You have the option to set the minimum and maximum number of keywords to include in each cluster, too.

I was pretty happy with the output from Zenbrief. It includes some data at the top, as well as links to each keyword cluster it’s created. The clusters are listed in tiles, with the primary keyword above.

The keyword clusters were logical and relevant to the topic I chose, so I would rate Zenbrief higher than SEO Scout on this count.

I also liked how the CSV was organized. Instead of the two column layout most tools provide, it puts each keyword cluster in its own column, which is much easier to read in my opinion.

For a free tool, I was impressed with Zenbrief. It does lack the SERP data a paid tool can provide for additional context, but apart from that I would say it’s on par with some of the paid tools I tried.

Usage Limits

Zenbrief lets you cluster up to 30,000 keywords for free.

Contadu

Contadu offers several content strategy and optimization tools. It has two free tools: a keyword mixer and a keyword clustering tool.

Keyword Clustering in Contadu

Contadu offers a unique option for keyword clustering. You can group keywords based on similarities in subwords, or you can provide the groups yourself and Contadu will sort your keywords into them.

I used the semantic keyword grouping tool first.

Like SEO Scout, the keyword clusters it returned weren’t very useful.

If you already have a keyword list and subtopics you want to write about, and just need to sort your secondary keywords, using Contadu to assign keywords to predefined groups could be very useful.

Granted, this method requires a lot of manual research and work before you can create your clusters.

Usage Limits

Contadu allows you to cluster up to 100,000 keywords for free.

If you upgrade to the paid version of Contadu, you gain access to more data, like search intent, competitor analysis, and performance potential of your keyword clusters.

ChatGPT

In my experience, using ChatGPT for SEO, content strategy, oe keyword research is a bit of a mixed bag.

It’s always important to keep in mind that ChatGPT doesn’t have access to all the same data as an SEO platform like Semrush, and that these tools can hallucinate and provide inaccurate information.

ChatGPT also sometimes gets overwhelmed if I ask it to do too much at once. That said, if your keyword list isn’t too long, you can definitely use ChatGPT as a keyword clustering tool.

Keyword Clustering with ChatGPT

The first step I took to create keyword groups with ChatGPT was compile my keyword list. I exported the same “paddleboarding techniques” list I’ve been using throughout this post from Semrush.

Then I worked on my prompt:

This last direction not to hallucinate doesn’t always work, but it’s worth including it to try to mitigate extra keywords slipping into your list.

My keyword list is 1,179 words long. ChatGPT would give me about five or six clusters at a time, and then I would have to prompt it to continue. It completed 30 clusters — about a quarter of my list — before I reached the usage limit.

As far as the quality of the output goes:

• ChatGPT did not add any keywords that weren’t in my list for the clusters I cross checked
• I also felt that the clusters were more usable than the ones I got from SEO Scout or Contadu
• The topics were relevant and weren’t repetitive

Usage Limits

ChatGPT states that users on the free tier can only send a certain number of messages in a five hour window, although it doesn’t specify exactly how many messages that is. Sending larger messages (like a keyword list) will likely cause you to reach the limit faster.

I was able to cluster a little over 300 keywords before hitting the usage limit for ChatGPT. I would say that if your keyword list is longer than 500 words, it will probably take an unreasonable amount of time to cluster them on the ChatGPT free tier.

Free vs. Paid Keyword Clustering Tools

If you’re on the fence about paying for a keyword clustering tool or using a free one, there are a few things I would keep in mind:

• Accuracy. Free tools often don’t have access to SERP and keyword data like paid tools do. The keyword groups they create are based only on similarities in the terms used, which means they might not actually be relevant or use the best keywords to maximize the traffic potential of your content.
• Usage limits. If you’re planning to rely on free tools long-term or for a large site, you might run out of credits and be left looking for a new solution.
• Functionality. Think about the other tools and features the platform provides in addition to keyword clustering. A multi-purpose platform will give you a lot more bang for your buck, and help improve your workflow efficiency because you won’t have to switch between browser tabs or copy and paste information.

Sometimes budget constraints can restrict your choices when it comes to which tools you can use. I know I’ve relied on lots of free SEO tools when working on personal projects and even for some freelance clients.

If you don’t have any money to spend on a keyword clustering tool, I suggest Zenbrief. It produced the best results of the free tools I tested.

However, if you can invest in a paid tool, I would recommend Semrush. I like that it provides multiple ways to create your keyword clusters, gives you a lot of data to work with as well as recommendations on how to organize and prioritize your content, and that you can incorporate keyword grouping seamlessly into your larger keyword research workflow.

The best way to know if Semrush is the right keyword clustering tool for you is to try it yourself.