Research. Semrush vs Ahrefs. Backlinks discovery test for 107 websites.

Backlinks are the second major ranking factor for websites on Google search.

In one of my previous research, we compared the ability of all SEO tools to discover backlinks.

Two winners were Semrush and Ahrefs. All others discovered fewer backlinks and were significantly slower.

So, it’s an excellent time to compare the leaders head-to-head.

Comparing Backlinks Discovery for 100+ Sites

This experiment was conducted by the product team behind Empire Flippers – one of the leading website resellers in the US and worldwide. They kindly shared the dataset with me and permitted me to publish the results.

The EF team took 107 websites for sale from their database and obtained backlink data from Ahrefs and Semrush.

The goal was to compare the backlinks discovery performance of both tools, comparing all the data available through API.

It includes Semrush Authority Score (AS) and Ahrefs Domain Rating (DR), number of referring URLs, number of backlinks, specific types of backlinks, such as texts and pictures, follow or nofollow attributes, links from .gov and .edu websites.

For illustration purposes, I’ll only take the critical parameter – the number of backlinks discovered by both tools.

It’s illustrative enough and reflects the general outcome of the experiment.

I’ll leave the link for the research raw data at the end of this article if you want to check the whole dataset.

Key Takeaways

Here are the key takeaways from the study:

1. In total, Semrush discovered 6.93M links and Ahrefs discovered 2.43M links.

That’s more than 2.8X the links Semrush discovered compared to Ahrefs.

Overall, Semrush discovered far more backlinks than Ahrefs.

Now, let’s examine this at the website level.

2. On the website level, Semrush found more backlinks for 93 out of 107 websites (87%). Whereas Ahrefs discovered more links for the remaining 14 sites (13%).

Number of backlinks discovery cases won by each vendor:

Here is what the difference in the distribution looks like:

Orange represents the % of backlinks found for each domain by Semrush and purple – by Ahrefs. You can visually see how much better Semrush performs in the backlinks discovery.

A few points on this graph are worth mentioning, bringing us to our next observation.

3. Ahrefs has “blind spots” on a few (4.7%) domains.

Ahrefs found zero backlinks for five domains, while Semrush found at least a few backlinks.

The difference was huge in two cases – Semrush discovered several thousands of backlinks.

The opposite is not true – Semrush blind spots weren’t detected. This means that if Ahrefs has the domain data, Semrush will also have it.

4. For 65% of domains, Semrush discovered more than 3X the backlinks Ahrefs discovered.

This means Ahref’s share of the total number of backlinks found was below 25% for 70 (out of 107) sites.

In other words, Semrush not only won a large number of cases but also won big.

Bottomline

Based on this data, there’s a clear winner between the market leaders.

Regarding backlinks, Semrush is performing better in the vast majority of cases.

If you want to dive deeper into the experiment data, here’s a link for the raw numbers.