Just how good are backlink tools such as Open Site Explorer, Majestic SEO and ahrefs at identifying links to the pages of your site? That’s the question we set out to answer in this study, and for many of you, the answer may come as a shock!
(Want a quick summary of the results? See our 3-minute video and 12-slide deck at the end of this post!)
Bottom line is that they all fail to report on many links, even from very prominent sites. However, this study is not meant to indict them. They remain incredibly valuable, and a core part of any SEO toolset.
In this post, I will present the results, as well as provide you with my thoughts on how this impacts your SEO strategy. At the end of the post you’ll find a video where we summarize the findings.
[Tweet “No backlink tool finds all links, but they are still useful. See study at”]
How We Structured the Test
We picked a group of 20 sites that share all of these characteristics:
- Strong tendency to link out to other web pages in their content
- Implemented links are NOT NoFollow
- Reasonable to a high degree of prominence
The 20 sites we tested were:
We then reviewed the outbound links in three articles per month on each of these sites, starting in June of 2014, and ending with November of 2015. For each of those outbound links (the “Tested Links”), we noted the page that the link pointed to (the “Receiving Page”). We took the URL of Receiving Page, and plugged it into each of the three tools to see which tools identified the Tested Links.
Across the 20 sites, we ended up identifying 2681 outbound links, so this gave us a decent amount of data as to what was happening with each tool.
Let’s dive right in with a snapshot of the results:
In our test, Majestic discovered the most links, netting just over 60 percent of the Tested Links being found. OSE came in at 55.3 percent and ahrefs came in at 50.5 percent.
[Tweet “Study finds no major backlink tool finds more than 60% of links.”]
Important: Considering the size and the scope of the web, this test covers a very small sample size. In addition, this test is deliberately biased toward high authority sites, so this test says nothing about the effectiveness of the tools on lower authority sites. For that reason, I’d argue that all three tools are pretty competitive with each other.
We also looked at the overall performance of the three tools over time:
You can see that no tool identified more than 74 percent of the links in any given month, even on these very prominent media sites. Moz returned the most links in 12 of the 17 months tested, with a strong tendency to find more of the older links on these sites. Majestic returned the most links in five of the cases. While ahrefs didn’t return the most links in any given month, it was competitive throughout.
Also note that the Moz data was pulled via their API. Moz only returns links via their API that have already had their metrics calculated, such as Domain Authority and Page Authority. As a result, these numbers don’t include their “Just-Discovered Links”, and this probably causes October 2014 to come in lower than it otherwise would have.
We also looked at the aggregate coverage of all three tools together:
In aggregate, this brought overall coverage up to just over 80 percent of all the links, a significant improvement over any one individual tool.
[Tweet “The three major backlink tools together find about 80% of links to a site. See study”]
One last thing that I looked at was to see if the data would change much if we looked at only the sites that were Moz Domain Authority 90 or higher:
This did indeed cause a slightly higher success rate for all three tools.
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The major conclusions are as follows:
- All three tools were competitive in finding links across the tested sites.
- Even on very high DA sites, no tool found all the links.
- Using all three tools together provided the greatest coverage.
- There was evidence that the tools bias toward coverage on higher authority sites.
More conclusions and takeaways after the video and slide deck below.
Click here to get an infographic summarizing the findings of this study.
Here is a video summarizing the findings of this study:
And here’s a slide deck summary of the study findings:
If you are serious about backlink analysis, it makes sense to obtain access to all three tools. Their coverage has significant overlap, but they also all find links that the other tools don’t. That’s why at Perficient Digital we built our own in-house tool to aggregate the data from these three, plus add data of our own, to give our clients the best possible link analysis.
It is also likely that coverage of links drops in all three tools across sites of lower authority. We saw some evidence of that, and it does seem to make sense that they would spend more time on discovering the highest value links. It’s also my (speculative) opinion that the value of using all three tools together goes up even more as you get to lower authority sites.
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