Keyword Clustering: What It Is & The 5 Best Tools to Get It Done

Introduction to Keyword Clustering Tools

Keyword clustering is the process of grouping similar keywords together based on their relevance and search engine ranking similarities. Instead of treating each keyword as an isolated entity, clustering helps SEO professionals structure content more effectively, ensuring that multiple keywords can be targeted within the same page to maximize search visibility.

For example, imagine you’ve conducted keyword research on “cbd oil” and gathered a list of 1,000 keywords. Analyzing each one individually would be impractical. Keyword clustering helps by organizing these keywords into meaningful groups, making it easier to plan, produce and optimize content efficiently on the back of the clusters.

How SERP Based Clustering Tools Actually Work

Keyword clustering tools work in straightforward ways that give practical benefits:

They Group Related Terms by looking at what they mean or how search engines treat them. For example, “dog training tips,” “how to train puppies,” and “dog behavior training tips” might all be grouped together despite using different words if 3-4 common pages ranking for all of these keywords in Google.

Here is a short video on how clustering works.

In some instances two keywords that look very similar might have two completely different search results. In these instances its best to have two separate pages targeting them.

In this example ‘vape accessories’ and ‘vaporizer accessories’ both keywords might seem similar but search results are completely different.

Quick tip. You can use our SERP Similarity tool to quickly check overlap between two keywords. Our premium version allows you to check up to six keywords.

For more detailed explanation check our Keyword clustering guide.

Free vs Paid Clustering Tools

Here are the main differences:

Free Keyword Clustering Tools

Free tools are like using a basic calculator. They’ll get simple jobs done but have limits:

• They might only handle a few hundred keywords at once.
• Often use basic “this word sounds like that word” matching.
• Some use semantic methods to match keywords and are often inaccurate.
• Frequently give odd groupings that don’t match how people actually search.
• Due to high costs these tools won’t use SERP data to group keywords.

Paid Keyword Clustering Tools

Paid tools are more like having a professional accountant. They cost money but save time and give better results:

• Can process thousands or even millions of keywords.
• Use much smarter algorithms and live SERP data to group keywords.
• Connect with ranking data, competitor analysis, and content planning tools.
• Allow you to customize how strict or loose the groupings should be and various other customization options.

Top 5 Keyword Clustering Tools

Below, we explore the top five keyword clustering tools that stand out in the industry.

1. Keyword Insights

The Keyword Insights platform offers a sophisticated keyword clustering tool that automates this process at scale, providing several benefits to SEO efforts:

• Data-Driven Clustering: The tool analyzes live, country-specific SERP data to group keywords with similar ranking URLs, ensuring that clusters reflect current search engine landscapes. It doesn’t rely on Semantics or NLP programs and thus increasing the accuracy and giving users a reflection of what Google is ranking and expecting to rank.

• Scalability: Capable of processing up to 200,000 keywords simultaneously, the platform accommodates extensive keyword lists, making it suitable for large-scale SEO projects. Most clustering tools can’t process more than 15,000 keywords at a time on average.

• Comprehensive Reporting: Each clustering report includes metrics such as average rank, search intent, potential traffic opportunities, difficulty scores, and SERP features. This data empowers users to prioritize content development and identify valuable opportunities.

• Competitor Analysis: The platform features a competitor visibility map, illustrating how rivals rank for key keyword clusters and highlighting gaps in the user’s own content, facilitating strategic planning.

• Customizable Algorithms: Offering multiple clustering algorithms and advanced settings, users can tailor the tool to their specific niche and strategy, providing flexibility and precision in SEO efforts.

• Native Google Search Console Support: Native integration with Google search console offers the ability to quickly extract keywords from GSC and spot gaps and content opportunities.

Pros:

• Superior Scalability – Can process up to 200,000 keywords at once, making it ideal for large-scale SEO projects. Most tools cap clustering at 10,000–15,000 keywords on average, which isn’t sufficient for enterprise SEO or content-driven brands.

• Data-Driven Accuracy – Uses real-time, country-specific SERP data to cluster keywords based on actual Google ranking behavior. This is far superior to tools that rely on semantic grouping or NLP-based clustering, which can be inaccurate.

• Customizable – Offers Multiple Clustering Algorithms and soft and hard clustering methods, allowing users to customize their clustering strategy based on their niche and ranking behavior.

• Customizable – Compared to other tools, Keyword insights provides multiple pricing models which are designed to suit anyone from an SEO freelancer to an enterprise.

Limitations:

• Requires SEO Knowledge – While it provides comprehensive reports, users need some SEO expertise to interpret the data properly. Beginners might need some time to understand clustering strategies fully.

• Processing Time for Large Datasets – Although it can handle large amount of keywords, running such large datasets takes time. This is expected given the depth of SERP analysis, but it may be slower than simpler, less accurate clustering tools.

2. Semrush Keyword Strategy Builder

Semrush’s Keyword Strategy Builder is a versatile tool designed to do Keyword clustering, offering several features:

• Automated Clustering: By inputting up to five seed keywords, the tool generates a structured roadmap of topics and subtopics, automatically grouping related keywords into clusters. This facilitates faster content production and a more organized content strategy. 

• Comprehensive Metrics: Each cluster is accompanied by important metrics such as search volume, keyword difficulty, and search intent. This data enables users to assess the potential of each topic and prioritize content development accordingly. 

• Integration with Content Tools: Clusters can be seamlessly exported to Semrush’s SEO Writing Assistant, aiding in the creation of optimized content tailored to each keyword group. 

Pros:

• User-Friendly Interface: The tool offers an intuitive platform that simplifies the clustering process, making it accessible even for users with limited SEO experience.

• Visualization Options: Users can visualize clusters through mind maps or tables, aiding in the understanding of content hierarchies and relationships between topics. 

• Comprehensive SEO Suite: As part of the broader Semrush ecosystem, the Keyword Strategy Builder integrates seamlessly with other SEO tools, providing a holistic approach to digital marketing.

Limitations:

• Keyword Processing Cap: The tool allows for the analysis of up to 2000 keywords simultaneously, which may be limiting for medium to large-scale projects requiring more extensive keyword processing. 

• Pricing Structure: Access to the Keyword Strategy Builder requires a subscription to Semrush’s premium plans at $139 /month, which may be cost-prohibitive for small businesses or individual users. 

• Limited Customization: The tool offers no options for customizing settings such as different clustering algorithms or URL overlap compared to some specialized platforms, potentially affecting precision in niche markets.

3. Ahrefs Keywords Explorer

Ahrefs’ Keywords Explorer is a comprehensive tool designed to facilitate fast keyword clustering, offering several features:

• Instant Clustering: The tool uses a hybrid approach (SERP + Semantic) by grouping keywords by Parent Topic, allowing users to see related keywords clustered together instantly.  

• Comprehensive Metrics: Each cluster provides essential metrics such as search volume, keyword difficulty, and traffic potential, enabling users to assess the viability of targeting specific keyword groups. 

• Integration with Site Explorer: Users can analyze competitors’ keywords by using Ahrefs’ Site Explorer, facilitating strategic planning based on competitor performance. 

Pros:

• Speed and Efficiency: Ahrefs’ clustering process is fast, capable of grouping thousands of keywords in seconds, which is advantageous for users requiring quick insights. 

• User-Friendly Interface: The intuitive design of Keywords Explorer makes it accessible to both novice and experienced SEO professionals.

• Comprehensive SEO Suite: As part of Ahrefs’ extensive toolset, Keywords Explorer integrates seamlessly with other features, providing a holistic approach to SEO analysis.

Limitations:

• Keyword Processing Cap: The tool allows for the input of up to 10,000 keywords at a time, which may be restrictive for large-scale projects requiring more extensive keyword analysis. 

• Clustering Methodology: Ahrefs’ clustering is based on the Parent Topic, which relies on the top-ranking page for a keyword. This approach may be less precise than methods analyzing the entire SERP, potentially affecting accuracy in certain contexts. 

• Pricing Structure: Access to Keywords Explorer requires a subscription to Ahrefs’ premium plans, which may be cost-prohibitive for small businesses or individual users. Even though they offer a $29 mo cheaper plan but its extremely limited in terms of the number of credits (100) which will prevent you from running large scale clustering projects.

4. SE Ranking’s Keyword Grouper

SE Ranking’s Keyword Grouper is a tool designed to assist users in organizing keywords based on their SERP similarity.

• Automated Clustering: The tool groups keywords by analyzing the top 10 search results, identifying common URLs to form clusters.

• Flexible Settings: Users can customize clustering parameters, such as selecting the country, location, language, and grouping method (soft or hard clustering), to align with specific SEO objectives. 

• Search Volume Integration: The tool offers an optional feature to check the search volume of keywords during clustering, providing data to prioritize keywords without additional tools. 

Pros:

• Time Efficiency: The Keyword Grouper can process up to 10,000 keywords in approximately 10 minutes (Claimed), significantly reducing the time required for manual grouping. 

• Error Reduction: Automated clustering minimizes the potential for human error, ensuring more accurate keyword organization. 

Limitations:

• User Interface: The tool’s basic UI stuck in 1990s may not meet the expectations of users seeking a more modern and intuitive design, potentially impacting user experience.

• Lack of Integration: Unlike more comprehensive platforms, SE Ranking’s Keyword Grouper does not seamlessly integrate with tools for creating content briefs or writing, necessitating additional steps for users to develop content strategies.

• Competitor Analysis Deficiency: The tool lacks features for competitor visibility within the clustering process, limiting users’ ability to assess how competitors are targeting similar keyword clusters.

• Lack Cluster Visualization: The tool outputs clusters into a Google sheets and lets you get on with it. No visualizations or filters to help users to get the most of out of the clusters.

• Generalist Approach: As part of an all-in-one SEO platform, the Keyword Grouper may not offer the depth and specialization found in dedicated keyword clustering tools, potentially leading to less nuanced insights.

5. Surfer SEO’s Keyword Research Tool

Surfer SEO offers a Keyword Research Tool designed to assist users in discovering relevant keywords and organizing them into clusters to enhance content planning and search engine optimization efforts.

• Automated Keyword Clustering: By inputting a seed keyword, Surfer SEO generates a list of related keywords grouped into clusters based on common topics and search intent.

• Comprehensive Metrics: Each keyword cluster is accompanied by metrics such as monthly search volume and keyword difficulty, enabling users to assess the potential traffic and competitiveness of targeting specific clusters. 

• Content Planning Integration: The tool provides insights into search intent and potential organic traffic for each cluster, assisting users in prioritizing topics and structuring their content strategy effectively. 

Pros:

• User-Friendly Interface: Surfer SEO’s intuitive dashboard and clear data visualization make it accessible for users at various levels of SEO expertise. 

• Seamless Integration: The tool integrates smoothly with Surfer SEO’s Content Editor, allowing users to directly implement keyword clusters into their content creation workflow. 

• Search Intent Analysis: By factoring in search intent, the tool aids in creating content that aligns closely with user queries, potentially improving relevance and engagement. 

Limitations:

• Limited Scalability: Surfer SEO’s Keyword Research Tool may not efficiently handle extremely large keyword datasets, making it less suitable for extensive projects requiring the processing of hundreds of thousands of keywords simultaneously.

• Lack of Competitor Analysis: The tool does not provide in-depth insights into competitor visibility within the clustering process, limiting users’ ability to benchmark against industry rivals.

• Generalist Approach: As part of an all-in-one SEO platform, the Keyword Research Tool offers a broad range of features but may lack the depth and specialization found in dedicated keyword clustering tools, potentially leading to less precise clustering outcomes.

Final thoughts

Keyword Insights stands out as the most advanced and scalable keyword clustering tool on the market, offering unparalleled accuracy, deep competitor analysis, and seamless content integration. Unlike other tools that struggle with limited keyword processing, rigid clustering models, and lack of competitive insights, Keyword Insights provides a data-driven, fully customizable solution that empowers SEO professionals to make smarter, more strategic decisions.

Unmatched Scalability & Performance

With the ability to process up to 200,000 keywords simultaneously, Keyword Insights is built for enterprise-level SEO projects. Most tools cap their clustering at a fraction of this capacity, making them impractical for handling extensive keyword lists.

Precision Through Real-Time SERP Data

Rather than relying on static databases or generic semantic analysis, Keyword Insights leverages live, country-specific SERP data to group keywords based on real-world ranking behavior. This ensures that clusters reflect Google’s current expectations, leading to more accurate content planning and better search performance.

Deep Competitor Visibility & Strategic Insights

One of the most significant advantages of Keyword Insights is its Competitor Visibility Map, which highlights gaps in your content strategy by analyzing competitor rankings. Unlike other tools that provide only basic clustering Google sheets exports, Keyword Insights allows users to see which competitors dominate specific keyword groups, helping them identify untapped opportunities and areas for strategic growth.

The cluster-level competitor map provides a detailed view of your competitors visually, displaying their data alongside their rankings.

The table view displays key insights, including estimated traffic and domain strength, measured using the Moz DR metric.

Topical clusters indicate the extent of a domain’s topical coverage by analyzing keyword clusters and their rankings.

Comprehensive Reporting for Smarter Decision Making

Every clustering report includes critical SEO data, such as:

✔ Average rank – Understanding where you currently rank as a cluster.

✔ Search intent – Ensuring content aligns with user/search engine expectations.

✔ Traffic potential – So you can prioritize high value opportunities.

✔ Ranking data – Shows the target domains current rankings and performance.

✔ SERP features – Identifying quick-win possibilities. e.g: Featured Snippets.

✔ Cluster difficulty – Shows how difficult it is to rank for that cluster.

✔ Search intent explanation – Analyzes the SERPs and provides a detailed analysis of the intent using AI.

This level of detail ensures that SEO professionals can prioritize their efforts effectively, saving time and maximizing ROI on content creation.

Customizable Algorithms for Maximum Flexibility

SEO strategies differ across industries, and a one-size-fits-all approach doesn’t work for keyword clustering. Keyword Insights offers multiple clustering algorithms and adjustable thresholds, allowing users to tailor clusters based on niche-specific ranking behaviors.

This flexibility ensures that users get the most relevant keyword groups for their unique needs, whether they’re targeting local SEO, international markets, or competitive industries.

Seamless Integration Into Content Strategy

Unlike tools that focus solely on grouping keywords, Keyword Insights ensures that the clustering process flows naturally into content creation.

Users can take their clusters and immediately translate them into data-driven content briefs, eliminating gaps between SEO research and execution.

Then from the briefs go a step further and write, optimize and publish the content.

The Superior Choice for SEO Professionals

For SEO agencies, SaaS companies, and content marketers, Keyword Insights is the ultimate tool for high-performance keyword clustering. By combining scalability, real-time accuracy, deep competitor analysis, and a seamless workflow, it provides a truly superior alternative to traditional clustering tools.

For those who require precision, flexibility, and actionable insights, Keyword Insights is the go-to choice for building smarter, data-driven SEO strategies.