Rankfill

How to Check Competitors for SEO Gaps You Can Fill

You publish a post. You wait. Nothing. Then you search for the keyword you wrote it for and see the same three competitors sitting in positions one through three — sites you've been watching for months, wondering what they know that you don't.

The honest answer is usually this: they're not smarter. They've just built content around keywords you haven't checked yet.

Checking competitors for SEO gaps is the shortest path from "why isn't my site growing?" to a concrete list of things to build. This guide walks you through exactly how to do it.

What You're Actually Looking For

When people say "check competitors," they usually mean one of three things:

  1. Keywords competitors rank for that you don't — the most actionable gap
  2. Topics competitors have covered that you haven't — useful for content planning
  3. Pages ranking well that you could outrank — the direct opportunity

All three overlap. A competitor ranking for 50 keywords you don't have a page for is both a keyword gap and a topic gap. The goal is to find those gaps systematically rather than stumbling onto them one by one.

Step 1: Identify Your Real Competitors

Your SEO competitors are not necessarily your business competitors. A local plumber might compete with Home Depot for "how to fix a leaky faucet" even though Home Depot is not a business rival.

Find your search competitors this way:

Search for three to five keywords you care about. Note every domain that appears consistently in positions one through ten. Those are your SEO competitors for that topic cluster.

Then go one level deeper: use a tool like Ahrefs, Semrush, or Moz and look for the "organic competitors" or "competing domains" report. These tools calculate overlap — how many keywords both you and another site rank for. High overlap means high relevance.

Make a shortlist of five to eight competitors. More than that gets unwieldy. Fewer than three gives you a narrow picture.

Step 2: Pull Their Keyword Rankings

This is where the actual gap analysis starts.

Every major SEO tool has some version of a keyword gap report. Here's how to use each approach:

Using Ahrefs

  1. Go to Site Explorer and enter a competitor's domain
  2. Click Organic Keywords — this shows every keyword they rank for
  3. Filter by position (1–20 to focus on ranking pages, not deep-page scraps)
  4. Export to CSV
  5. Do this for each competitor
  6. Then go to Content Gap under your own domain, enter competitor domains, and Ahrefs will show you keywords they rank for that you don't

The Content Gap report is the fastest path. But the manual export approach is useful when you want to study a single competitor closely before cross-referencing against yourself.

Using Semrush

  1. Go to Keyword Gap under the Competitive Research section
  2. Enter your domain and up to four competitors
  3. Filter by Missing keywords — these are keywords competitors rank for where your site doesn't appear at all
  4. Sort by volume, then by keyword difficulty

The "Missing" filter is the most useful view here. Don't get distracted by the "Weak" category (where you rank, but lower than competitors) until you've exhausted the missing list.

Using Free or Lower-Cost Tools

If you're not paying for Ahrefs or Semrush, you have options:

The paid tools are worth it if you're doing this regularly. If you're doing a one-time audit, use Semrush's free trial (you get 10 reports) or Ahrefs' limited free mode.

For a deeper look at tooling options, this breakdown of Screaming Frog alternatives for content gap analysis covers several crawlers and gap tools worth knowing about.

Step 3: Interpret the Gap Data

Raw keyword lists are noise until you filter them. Here's the filtering logic that makes the list usable:

Keep keywords that are:

Remove keywords that are:

After filtering, you'll usually find a useful list is 20–30% of the raw export. The rest is noise.

Step 4: Prioritize by Opportunity, Not Just Volume

High volume does not mean high opportunity. A keyword with 10,000 searches and difficulty 85 is harder to capture than one with 800 searches and difficulty 28 — especially if your domain is relatively new or thin on content.

Score your gap keywords using this simple framework:

Factor Weight
Search volume High
Keyword difficulty High (inverse — lower difficulty scores higher)
Your existing domain relevance Medium
Content you could produce quickly Medium
Business value of the traffic High

You don't need to build a spreadsheet formula. Just scan the list and tag each keyword as high, medium, or low priority. Focus your first month on the high-priority ones.

Learning how to analyze competitors and steal their keywords in detail — including the prioritization layer — is worth doing before you start building content, because it keeps you from wasting effort on keywords that look attractive but won't convert.

Step 5: Analyze the Competitor Pages That Are Ranking

Before you write anything, look at the actual pages ranking for your target keywords.

For each high-priority gap keyword, open the top three results and note:

Old, thin content with few links is your best opportunity. Fresh, deeply researched pages with strong link profiles are going to take longer to displace.

If the top results are all 2,000-word guides with 200 backlinks each, either deprioritize that keyword or plan something significantly better than what's already there.

Step 6: Check What's Missing From Their Content

This is the step most people skip, and it's where real gaps live.

Look at the top-ranking competitor pages and ask: what question does this not answer that a reader might still have?

Common gaps you'll find:

If you can find a genuine gap in the content itself — not just in keyword targeting — you have a real reason to outrank them over time. Analyzing a competitor website for SEO gaps at the page level like this is what separates a strategic content plan from a list of topics to copy.

Step 7: Build a Content Plan Around the Gaps

Now you have a prioritized keyword list and a sense of what angles competitors haven't covered. Turn that into a content plan.

For each target keyword:

A realistic cadence for a small team: two to four pieces per month, with older posts being updated as the new ones ship. Don't try to close all gaps simultaneously. Prioritized, consistent output compounds better than a burst of 20 posts followed by three months of silence.

Step 8: Track Whether It's Working

After you publish, monitor progress:

If a page isn't appearing at all after six weeks, the likely issues are:

Doing This at Scale

The process above works for a handful of competitors and a few dozen keywords. If you're trying to do this across a large site or want to close gaps across an entire market quickly, the manual approach gets slow.

At that point you have options: hire an SEO agency, use an in-house analyst to run regular gap reports, or use a tool that automates the mapping. Rankfill, for instance, does this — it maps every keyword competitors in your market are capturing that your site isn't, and estimates the traffic you could recover — which can be a faster starting point than building the analysis from scratch.

Whatever approach you use, the underlying logic is the same: find where competitors are collecting search traffic you're not, understand why, and build content that answers the same question better or for an angle they missed.

Common Mistakes When Checking Competitors

Targeting competitors that aren't your real search rivals. Your biggest sales competitor might not overlap with you on search at all. Run the organic competitor report first.

Ignoring keyword intent. A competitor ranking for "what is X" (informational) and "buy X" (transactional) are two different opportunities with different pages and conversion implications.

Not checking your own existing content first. Before building something new, check if you have an old post that covers the topic but ranks on page three. An update is faster than a new piece.

Skipping the competitor page analysis. A keyword gap tells you there's an opportunity. Looking at the actual ranking pages tells you whether you can take it and how.

Building a plan and then not executing. The gap analysis produces a list. The list only matters if content gets published.

FAQ

How often should I check competitors for SEO gaps? Once a quarter is a reasonable default. Markets shift, new competitors emerge, and your own rankings change — so a quarterly review keeps the plan current without turning into a full-time job.

Can I do this without paid tools? Yes, but partially. Google Search Console shows what you rank for. Free trials of Semrush or Ahrefs get you a snapshot. For ongoing analysis, a paid tool is worth it. At $99–$130/month, either pays for itself if you capture even a small amount of additional organic traffic.

How many competitors should I analyze? Three to five is the practical sweet spot. More dilutes your focus. Less gives you a narrow view of the market.

What if all the gap keywords are too competitive? Look for long-tail variations. A keyword with difficulty 70 often has closely related phrases at difficulty 30 with meaningful (if smaller) search volume. Those are often faster wins.

My competitor has thousands of keywords. Where do I start? Filter for keywords with volume between 200 and 2,000 and difficulty under 50. That range typically contains the highest-value, most reachable opportunities. Sort by volume descending and work down the list.

Should I target the same keywords as competitors or find angles they missed? Both. Some keywords you simply need to compete on directly — those are the core topics in your market. But the biggest leverage is finding subtopics, questions, or user segments competitors haven't addressed well. That's where you can rank faster and with less effort.

How do I know if a gap keyword is worth writing about? Ask: if this page ranked and drove 100 visitors a month, would those visitors be relevant to my business? If yes, it's worth it. Traffic that doesn't convert to any goal — leads, sales, signups, ad impressions — isn't an opportunity, it's noise.

What's the difference between a keyword gap and a content gap? A keyword gap is a specific search term your competitor ranks for and you don't. A content gap is a broader topic or angle that isn't well covered anywhere — including by competitors. Keyword gaps are easier to find with tools. Content gaps require reading the existing pages and noticing what's missing. Running a full competitor site analysis usually surfaces both.