Moz vs SEMrush vs Spyfu vs Ahrefs: Which Is the Best SEO Tool?

Published: February 8, 2021

While there are plenty of SEO tools available, the four most popular in the industry are Moz, SEMrush, Ahrefs, and Spyfu.

Whether you’re running SEO for an enterprise-level business or improving a personal blog, finding the right tool can make a huge difference in your SEO strategy and overall site health.

Therefore, this post dives into key features, differences, and similarities of each tool to help you select the perfect solution for your business.

Specifically, I’ll examine their merits in these categories:

Keyword Research
Backlink Analysis
Technical SEO Tools/Site Audit
Rank Tracking
Unique Features
Support
Pricing and Value

Here we go!

Comparing Keyword Research Tools

Let’s begin by determining which tool is best for researching your keywords.

To compare the tools, I started with an analysis of each tool’s keyword volume estimates.

I checked the monthly search volume of 150 keywords across Google Adwords and all four tools and averaged them together to get a holistic view of the difference in estimates.

As you can see, among the four tools, Moz, Spyfu, and Ahrefs all have very similar averages, while SEMrush is a higher outlier.

These differences have to do with the methodologies they use to calculate their search volume. SEMrush uses an algorithm, while the rest use combinations of Google Adwords and clickstream data.

Unfortunately, gathering 100% accurate data is pretty much impossible.

For example, take a look at the data from Google Adwords, which you might expect to have the most accurate data. The average volume of these 150 keywords was 72,729—over 50,000 higher than SEMrush.

The discrepancies occur for a variety of reasons. For example, Google Adwords uses a rounded annual average. Therefore, a keyword like “Valentines Day gifts” might show a monthly volume of 1200, though the distribution might be closer to 1,000 in February and the other 200 spread out between March through January.

In addition, Google Adwords conflates keywords together. Therefore, if you have two synonyms like “NFL” and “National Football League,” Adwords might show you the same search volume for the two combined.

However, each tool differs in both how it calculates data and the frequency in which they update their search volume data.

We get a slightly different view when we look at median keyword volumes across the 150 keywords.

While still being a high-volume standout in comparison to the tools, Google’s median keyword volume is closer to the other tools. The few keywords that were clearly made of several combined keyword volumes have less of an impact.

Moz again has the lowest numbers, which when examining the data, happens because Moz shows a lot of keyword volume estimates as 5 searches per month, which brought the median down considerably.

Interestingly here, Spyfu has the highest median keyword volume compared to the other tools, rather than SEMrush, which means it had more total keywords on the higher side and fewer on the lower side.

With that out of the way, let’s get to the features.

Moz

Their Keyword Explorer tool includes four main features:

Keyword Overview
Keyword Suggestions
SERP Analysis

Put in your keyword, and the Keyword Overview provides a simple at-a-glance view of its Monthly Search Volume, Keyword Difficulty, and Organic CTR.

Image via Moz

A high Keyword Priority score (100) means that the keyword has a high organic CTR and volume, yet a low difficulty. Therefore, it should be a priority to rank for. However, a low Keyword Priority score means that you have a low organic CTR/volume and high difficulty.

If you click on “Keyword Suggestions,” you can find similar keywords and sort by a variety of different factors including volume, group keywords, and the type of keyword suggestion (for example, keywords based on similar topics vs keywords that contain your identical keyword).

Image via Moz

You can also get a closer look at the keyword’s SERP with Keyword Explorer’s SERP analysis.

This is helpful to get a quick overview of the SERP competition, with metrics like Page Authority, Domain Authority, Page and Root Domain Backlinks, and an overall Page Score for each.

Therefore, if you’re considering writing a post for a certain keyword, you’ll know whether or not you’ll have a shot at ranking for it based on the links that the top posts have.

Image via Moz

Pros:

The “Display keyword suggestions that” option allows you to pull up a list of broadly related keywords for more keyword ideas than most other tools
The priority feature and simple interface make it beginner-friendly

Cons:

Doesn’t provide metrics for SERP features, or even show the results in “Related Questions” or “People Also Ask.”
Excludes key metrics like organic click percentages, a visual breakdown of traffic geography (US, Canada, etc)
No PPC data

SEMrush

SEMrush’s keyword research tool is similar to Moz, but includes some extra metrics, which we’ll go over here.

Within its Keyword Research tool, SEMrush also offers:

Keyword Magic Tool
Keyword Manager
Organic Traffic Insights

The Keyword Overview provides a detailed report on the keyword of your choosing.

mage via SEMrush

It goes a little bit deeper than Moz by including:

CPC value
Global volume broken down by country
Total number of URLs in the SERP
Types of SERP features.

SEMrush also shows a PPC competition metric next to the CPC price. This gives you an idea of the competition level between advertisers over this keyword, on a scale of 0 to 1.0. A Score of 1.00 shown here means “Backcountry Skis” is extremely competitive.

Image via SEMrush

You also get keyword variations, related keywords, and questions, which can be helpful for finding long-tail keywords.

SEMrush’s Keyword Magic Tool can help you search for keywords to target, whether for SEO or PPC.

This tool is super filterable and sortable by Keyword Difficulty, CPC, Competitive Density, SERP Features, and results, making it easy to find the right keywords for your SEO campaign.

mage via SEMrush

Another cool feature on the left lets you look at keyword clusters—or keywords that often occur together. This is great for finding other relevant keywords to include in your post.

Pros:

Useful for those who also run PPC campaigns
Offers the most keyword features, along with Ahrefs

Cons:

It can be difficult to get the hang of, especially for beginners
Its user interface is a little overwhelming and not very clean

Spyfu

The sheer amount of metrics that Spyfu offers in its Keyword Research tool is impressive, including Advertiser History, Ranking History, Backlinks, SERP analysis, and a helpful Google Ads Advisor for PPC research.

Let’s dive into it.

The Keyword Overview page includes all of these tools mentioned above as modules, and you can also click on the tabs at the top to get greater detail for each.

You’ll see an overview of standard metrics like monthly volume, keyword difficulty, and CPC for each keyword.

However, it also shows some more unique and useful metrics like estimated clicks and “Clicked any result,” which shows the proportion of users that click on something. For example, you may find that some SERPs have a featured snippet that answers the user’s question and results in a no-click search.

You can also see the proportion of people who click on ads and whether they tend to search for this keyword on mobile or desktop, which can help tailor your PPC strategies.

Image via Spyfu

You can also see a variety of ways to browse new potential keywords, including questions for long-tail keywords and “Also buys ads for” to see what other keywords companies are spending money on in PPC.

Advertiser History quickly tells you who your top advertising competitors are and estimates their ad spend and coverage.

Image via Spyfu

Organic Ranking History provides a graph of the changes in rank of the results in the SERP over time.

Image via Spyfu

I like how it points out when Google implements algorithm changes, giving you a sense of the difference those changes make on you and your competitors’ progress.

Like the SERP analysis offered by Moz, Spyfu’s SERP Analysis goes a bit deeper, providing rankings for the first 6 pages of the SERPs. SERP features, however, are not included.

Image via Spyfu

In addition, they also recently came out with a competitive analysis keyword research tool that makes it easy to see what the most valuable keywords for your competitors are and sort those keywords by difficulty, topic, and much more.

Pros:

One of the most in-depth competitor keyword analysis tools, enabling you to track competition’s most valuable keywords and gains and losses.
The only tool that allows you to view historical rankings for up to five years for free
Extensive PPC information with an Also Buys Ads section and even makes recommendations for other great PPC keywords

Cons:

It doesn’t offer search volumes based on countries
Their keyword database is still growing, so much of the data it shows is only relative to other keywords in their database

Ahrefs

Ahref’s keyword research tool also offers a lot of data when it comes to their Keyword Explorer.

On the Keyword Overview page, you get Keyword Difficulty, Search volume, and CPC value as well as estimated clicks and volume by country.

The percentage of paid vs organic clicks over time is particularly interesting, as you can get a sense of what types of links are driving clicks in this SERP.

Image via Ahrefs

One thing I should note is that the keyword difficulty that Ahrefs shows for “backcountry skis” is radically different from the other tools, which ranged between 37 (Moz) and 82 (Spyfu).

The reason that Ahrefs differs so greatly is because of the way they calculate it. Ahrefs takes fewer variables into account when determining the score, which leads to a less nuanced view of a keyword’s difficulty.

There’s also a variety of ways to get new keyword ideas related to your topic:

Phrase match
Having same terms
Also rank for
Also talk about
Search suggestions
Newly discovered
Questions

For example, if we look into People Also Talk About, it shows the keywords and phrases that the top 100 ranking pages for your target keyword frequently mention.

Image via Ahrefs

Along with normal metrics, it tells you when it was updated (which is very often) and lets you look at the SERP overview as well as position history for each keyword.

Image via Ahrefs

Ahref’s keyword research tool also includes a nifty Ads History tool, which you can sort by domain and landing page to see who has been spending the most money on this keyword over time.

Image via Ahrefs

If you’re planning to run a PPC campaign, this helps you get a quick lay of the land and understand who your main competitors would be for different keywords.

Pros:

One of the most extensive keyword research tools with a large database
Easy user interface

Cons:

Their keyword volumes tend to range quite a bit compared to other tools
Not very good at showing other related keywords (for example, if you search for “pants,” it won’t show other keywords like “jeans.”

Comparing Backlink Analysis Tools

Let’s begin our analysis of backlink tools by comparing the respective platforms’ link index size. To do this, we’ll use a domain from the popular Outside Magazine, www.outsideonline.com.

Here’s what we get when we put this domain into each backlink index tool.

The first thing you’ll notice is that we don’t have data for Spyfu. The reason is that Spyfu only looks at backlinks that are in the first 50 pages of search results, so it can’t provide a full picture.

Moz has been able to detect the most linking domains, which are more straightforward to compare and more important than inbound links for ranking keywords.

SEMrush has detected the most inbound links by far, beating out Ahrefs in inbound links by 6.5 million. However, it’s important to note that each tool’s methodology impacts the results for inbound links and ranking keywords, so these aren’t great comparisons.

You’ll also notice that the number of linking domains are all very similar, with SEMrush Moz, SEMrush, and Ahrefs showing index sizes within a few thousand. SEMrush and Ahrefs are within less than 100.

Let’s dig into the features.

Moz

Moz’s Link Overview tool, Link Explorer, gives you a nice topline view of the types of metrics you would expect from a backlink analysis tool: Domain Authority, Linking Domains, Inbound Links, and Ranking Keywords.

Image via Moz

If you’re doing competitive research, you can easily download the links you need without having to do much digging.

You also can see the number of links that have changed over the last two months at a glance.

Image via Moz

For Inbound Links, Linking Domains, and Top Pages, there are individual pages that you can use to filter and sort by Domain Authority, the number linking domains, and Spam Score.

Image via Moz

You can also view anchor texts to see whether links tend to be branded (include the brand name) or generic (click here, etc.).

Image via Moz

Pros:

A recent study shows Moz does indeed have the largest link data set
Only tool that shows a spam score while scrolling through backlinks

Cons:

Downloading reports can be slow
Offers fewer features than SEMrush and Ahrefs