SEO Tools Comparison: Ahrefs vs. SEMRush vs. SpyFu vs. KWFinder

Let’s talk about those fancy SEO tools and their so-called perfect accuracy.

Do tools like Ahrefs, SEMRush, SpyFu, and KWFinder provide users with accurate data? What is the difference between Ahrefs and SEMrush? What about SpyFu and KWFinder?

Well, I hate to be the bearer of bad news - they aren’t as accurate as most people claim them to be.

Here’s a big mistake most people make, especially non-SEO folks - they think of these tools as the “holy grail of truth.”  But they are not. These tools are rather meant to be used as guidance. They show trends for common terms, but there is still opportunity out there, even if they say zero volume.

Allow me to present the evidence!

To do so, I am going to compare data from different SEO tools inside Gigasheet.

For those who are unaware of our platform, Gigasheet is a big data cloud spreadsheet platform with several exciting features like sorting, filtering, grouping and enchrihment.

Let's get started!

I Looked Up the Same Keyword on Ahrefs vs. SEMRush, KWFinder, and SpyFu

Millions of businesses use SEO tools like Ahrefs, SEMRush, KWFinder, and SpyFu. And you’re probably a part of one of them.

My favorite of the pack is Ahrefs. I use it a lot.

Recently, I had a call with Will, the Product Manager at Gigasheet, to discuss potential blog post ideas for the next quarter. I mentioned to him that I wanted to write about how companies can use Gigasheet to dive deep into their SEO competitive analysis data.

That’s when he proposed - “Hey Ankit! How about using Gigasheet to compare and analyze SEO keyword research data from different tools like Ahrefs, SEMRush, KWFinder, and SpyFu?”

I was left awestruck! Genius idea, Will!

To begin with, I looked up the keyword – “customer success” on four different SEO tools (we didn’t have access to all these tools, so had to purchase a one-month subscription for demonstration).

Keyword Results from SEMRush

Keyword Results from Ahrefs

Keyword Results from KWFinder

Keyword Results from SpyFu

Keyword Search Comparison Observations

• According to SEMRush, the keyword “customer success” has a United States volume of 6.6K. However, on Ahrefs, it’s 6.2K. As you can see in KWFinder, it’s 6.7K – similar to what SEMRush displayed us. But SpyFu shows that it’s 4.8K. KWFinder 6.7kSEMRUSH 6.6kAhrefs 6.2kSpyFu 4.8k
• On SEMRush, the keyword difficulty for the keyword “customer success” stands at 74% - which, according to the tool, is hard to rank. It’s a generic keyword – so yes, I believe it’s hard to rank. Ahrefs shows the keyword’s difficulty is 67. On KWFinder, it’s 46, and on SpyFu – it’s 36. SEMRUSH 74Ahrefs 67KWFinder 46SpyFu 36Big difference, but these tools have their own way of measuring KD! According to Harsh Shah, SEO Specialist at Databox, “The scale of KW difficulty is measured differently in every tool, so relying on these tools to decide whether you should go with a keyword or not can be a disaster sometimes; so instead, you can check the SERP results and see if there are any relatively new or medium rank websites are ranking or not.”
• The CPC across different tools also varied significantly. Ahrefs $9.00KWFinder $8.10SEMRUSH $3.97SpyFu $3.25

Believe me now? But that’s not where I stopped my analysis. I wanted to dive deeper!

Creating Lists for SEO Keyword Research

The next thing I did was prepare a list of 100 keywords – which I added to a blank spreadsheet (Google Sheets). Now, I fetched data for all these keywords from the four SEO tools I’ve mentioned in this post – SEMRush, Ahrefs, KWFinder & SpyFu and exported the results.

SEMRush Keyword Overview

Ahrefs Keywords Explorer

I don’t know why but Ahrefs could only find data for 95/100 keywords we provided the platform with.

But that’s fine.

KWFinder Upload Your List

KWFinder had a limit of looking up 25 keywords at a time (I don’t know if I was restricted by plan). So, I had to do it for 25 keywords one-by-one.

SpyFu Large Keyword List

SpyFu was only able to fetch data for 96/100 keywords. Again – that’s fine. We faced a similar problem while trying to bulk-look up SEO keywords on Ahrefs.

Now, let’s compare the data.

Combining SEO Keyword Data Under a Single Roof

I didn’t want to switch between spreadsheets just so I could compare the data. So, I thought of combining the CSV files. Now, while doing so, I wanted to eliminate the possibility of human error (yes, while copying data from multiple spreadsheets and pasting them into one, there’s always a chance of human error).

We obtained data in four different spreadsheets, from four tools, all of which had different formatting– we’re talking about the arrangement of column groups like search volume, global search volume, keyword difficulty, and more.

So, I modified all the exported data such that every spreadsheet had the following column groups only:

• Keyword
• Country
• Difficulty
• Volume – this is country volume
• CPC

Also, I added a column group called ‘Tool’ to every spreadsheet to make sure I was easily able to differentiate the data from one tool to another after combining spreadsheets.

Next, I uploaded these CSVs to Gigasheet.

Now, you may be thinking – “Why didn’t this guy use Microsoft Excel or Google Sheets for his analysis? Is he just concerned about promoting Gigasheet?”

Look – as a freelance content marketer hired by Gigasheet, one of my priorities is putting Gigasheet in front of the masses.

But here’s the thing – I am really picky about the companies I work with.

Platforms like Microsoft Excel and Google Sheets are genuinely good.

I love them. They have data entry and creation capabilities which do not exist in Gigasheet, which is primarily used for data exploration.

There are some areas where these tools have their limitations, but Gigasheet excels in these areas.

A few reasons I chose Gigasheet for analyzing and comparing my SEO keyword research data are:

• I wanted to combine data from different CSVs into one – without facing any challenges.
• Even though we’re playing around with CSVs, Excel and Google Sheets don’t support a few spreadsheet formats. You have to manually import data – which itself is complicated if you don’t use these platforms much.  
• I want to quickly analyze my data by adding filters and grouping my data by columns. I found applying filters and grouping data in Excel and Sheets complicated. But on Gigasheet, it’s simple.

Apart from this, I’d like to highlight that Gigasheet operates at a cloud scale and offers the ability to work on spreadsheets with billions of rows. On the other hand, Excel and Sheets have their own limitations:

• Google Sheets can process spreadsheets with no more than 10 million cells.
• Microsoft Excel’s rows and column limits stand at 1,048,576 and 16,384 respectively.

I can go on and on about why Gigasheet is amazing. But my inner content marketer is getting impatient and really wants to show you the difference between the SEO keywords data.  

After logging into Gigasheet, I created a folder called “SEO Tools Data Analysis” –

And I added all four spreadsheets to this folder:

The uploading part took me no time. And Gigasheet processed all four CSVs in less than a minute (subject to how large your spreadsheet files are).

Now, as I said, I wanted to have everything under one roof. I didn’t want to swoop between spreadsheets like an eagle. So, I decided to combine the CSVs.

So – here’s the thing – I didn’t do it by manually copying data from the four CSVs and pasting all of it into a blank CSV file. Instead, I used Gigasheet’s Combine feature.

How does it work?

Select the CSVs you want to combine and click on the “Combine” icon like this:

NOTE – To merge CSV files, you need to make sure all CSVs have the same column groups. Different SEO tools provided us with data in different formats. That’s the reason we did some restructuring above.

I named the combined file “Combined SEO Tools Data.”

Gigasheet combined the CSVs in no more than five seconds.

Now, let’s analyze it.

Here’s what the file looks like inside Gigasheet:

Time to play!

Analyzing SEO Keyword Research Data from Ahrefs vs. SEMRush

I used Gigasheet to compare the SEO data from four keyword research tools. The first thing I did was –

Applying Filters to SEO Keyword Data

Let’s see the difference between volume, difficulty, and CPC for the keyword “customer success stories.” To do it efficiently, I’ll add this filter:

Results –

My observation – Even though the volume is almost identical, the difficulty for the keyword varies a lot. On SpyFu, it shows 35, on Ahrefs it’s 58, SEMRush shows 53 whereas KWFinder shows that it’s 49.

Weird!

And just look at the CPC (USD).

It varies a lot.

For the keyword “customer success stories,” the CPC on:

• SpyFu – 6.7
• Ahrefs – 0.9
• SEMRush – 9.18
• KWFinder – 14.04

I also wanted to measure global volume, but it was hard for me to get global volume data for all four tools.

Let’s perform the same operation for another keyword – “what is customer success.”

In this case, along with keyword difficulty and CPC, volume varies a lot as well.

I looked up the same keyword on Google Keywords Planner. The volume, according to Google, stood between 1K and 100K. That’s a wide range. So it doesn’t really make sense for me to conduct keyword research solely based on data from Google Keywords Planner.  

Next, I Grouped Data by Column

I grouped data by the column group “Keyword.”

Results –

As you can see, all keywords are organized. I can click on them one by one and look at the differences in data like this –

Interesting, right?

Considering the column groups we have; this is a basic demonstration. But it’s enough to show that data fetched by SEO tools isn’t accurate.

So, you should not completely rely on SEO tools – as they are not the single source of truth even though they claim to be.

Other Opinions of SEO Keyword Research Tools

I just read a Twitter thread on the same topic from BowTiedWookie. The only difference is – this guy compared the data from SEMRush and Ahrefs to his own Google Search Console Data. And here are his observations:

In short, keyword research tools are not 100% accurate. Another important point I wanted to highlight here is - many companies out there have targeted zero-volume keywords that have helped them attract thousands of high-quality prospects and customers to their websites.

Experts talk about the impact of targeting zero-volume keywords on LinkedIn all the time –

1. Jakub Rudnik, Head of Content at Scribe

Four of Scribe’s best-performing articles target zero-volume keywords. According to Jakub, “At Scribe, many of our top traffic and signup-generating blogs are ZVKs or nearly so. We generally find them from what our customers say on social media, to our customer success team, or in user surveys. If they use specific terms for your product or the pain you solve, then other people are also using those terms. This isn't about writing topics without thinking of search volume -- SEO tools are still very useful for surfacing good terms. Instead, this is about using other data sources to fill in what SEO tools miss. Also, we focus on high-conversion terms -- keyword formats further down the funnel. So even if the traffic is lower, the conversion rates make up for the smaller overall audience.”

He even wrote a LinkedIn post about it -

2. Steven Macdonald, Head of Content at INEVO AS

3. Ankit Vora, Freelance Content Marketer & Writer (That’s Me)

I reached out to marketers for their insights on zero-volume keywords. And here’s what they had to say:

1. Deian Isac, Head of Agency Success at SPP.co

“I see a lot of potential in 0-volume keywords. Users word search queries differently, so it might seem like a long-tail query has no volume, but if you combine similar ones, there’s quite a bit of traffic potential behind the cluster. Young SaaS companies can leverage 0-volume keywords and answer very specific questions. It doesn’t even have to be a blog post; they could build an FAQ page. GMB Gorilla has used this exact strategy by creating an Ask the Gorilla section, leveraging 0-volume keywords such as “what do posts on google my business do.”

2. Dr. Fio D., Editorial Lead at Postmark

“The way I think about zero-volume keywords is that they don’t actually exist. What does exist is tools with limited or sampled datasets that record zero volume for specific keywords. So I generally ignore a volume of 0 and focus instead on whether the keyword or phrase looks and sounds like something would be typing if they wanted to find a service or tool I provide.”

3. Ryan Prior, Head of Marketing at Modash

“Zero-volume keywords can lead to big wins that aren't on your competitors' radar. The only difficult part is: how do you find them? My approach is to cover product use cases, and questions that our customer-facing teams get asked. That way, you remove the risk; even if this piece never drives substantial search traffic, it's still useful. ”

4. AbdulGaniy Sehu, Founder & Lead Content Strategist at Your Content Mart

“Most SaaS brands ignore keywords with zero or low search volume. This is because, they believe that if a keyword has zero search volume in an SEO tool, it means that no one is searching for it. In my experience, that's not usually the case. In fact, SaaS companies should leverage this undeserved opportunity to rank faster, dominate the SERPs in their niche, and grow MRR profitably. Some months ago, we identified the keyword “best ai writing assistant” and wrote an article targeting it for our client. Back then, it only had a global search volume of 20 or so, according to Ahrefs. Today, our client ranks in the top 3 on Google for that keyword, which now has a search volume of 210 in the US alone.”

Conclusions

SEO tools fetch their data from all sorts of mysterious sources (kind of like CIA intel). No SEO tool in existence will present 100% accurate data in front of you.

The sole purpose of this study isn’t to tell you that SEO tools are useless, but rather to emphasize that relying solely on them isn’t the best approach.

We wanted to dive deeper but didn’t have the resources and reach to conduct this study on a large scale. If you want to dive deeper, I recommended reading SparkToro’s blog post that offers an in-depth analysis of the same (recommended to me by Mariya Delano).

Also, I hope you loved Gigasheet. I didn’t want to say this out loud - but yes, I’m madly in love.

Try it today for free!

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