Rankfill

Find Keywords Used by Competitors and Fill the Gaps

You publish a post, wait three months, and it gets twelve clicks. Meanwhile, a competitor who launched six months after you is ranking on page one for every term you care about. You check their site — the writing isn't better. Their domain isn't stronger. But somehow they're capturing traffic you aren't.

The difference is almost always keywords. They're targeting terms you never thought to cover. This article shows you how to find those terms and what to do with them.

What You're Actually Looking For

"Find keywords used by competitors" sounds simple, but there are three distinct things people mean by it:

  1. Keywords they rank for that you don't rank for at all — these are pure gaps
  2. Keywords where they rank higher than you — overlap, but they're winning
  3. Keywords where you both rank weakly — opportunities nobody owns yet

The most valuable category is the first one. If a competitor is pulling in traffic from a keyword and your site has no content targeting it, that's a gap you can close with a single piece of content. The other two categories matter, but they require you to outperform existing content — harder, slower work.

The Manual Method (No Tools Required)

You can do a basic version of this for free.

Step 1: Pick two or three real competitors. Not industry giants you'll never beat. Competitors who are roughly your size or one tier above — the ones who keep showing up for searches you care about.

Step 2: Search for the topic you want to rank for. Look at who appears consistently on page one. Those are your targets.

Step 3: Run a site search. Type site:competitordomain.com [your topic] into Google. You'll see which pages of theirs Google has indexed for that topic area.

Step 4: Check their blog or content index. Most sites have a blog. Browse their post titles. You'll spot coverage patterns — topics they've clearly invested in, angles they've taken.

This gives you a rough map. It won't give you search volume, difficulty, or ranking position — but it tells you what content exists on their site that doesn't exist on yours.

The Tool-Based Method (Much More Complete)

Manual research misses most of the picture. A competitor ranking for 400 keywords is impossible to map by hand. You need a tool that has indexed search rankings at scale.

The main options:

Ahrefs — Enter any competitor's domain into Site Explorer. Under "Organic keywords," you'll see every keyword they rank for, with position, volume, and difficulty. The "Content Gap" feature lets you enter your domain and multiple competitor domains at once, then shows keywords they rank for that you don't.

Semrush — Their "Keyword Gap" tool works similarly. Enter your domain, add competitor domains, and filter for keywords where competitors rank but you have no position.

Moz — Less feature-rich for this specific task, but their True Competitor and keyword research tools cover the basics.

Google Search Console (for your own site) — This won't show competitor keywords, but it will show you queries where your site is getting impressions with poor click-through rates — terms where you exist but aren't competitive. Pair this with competitor data to prioritize.

For a step-by-step walkthrough of how to run this process inside these tools, this guide on competitor keyword research covers it in detail.

What to Do With the Data

Running the gap analysis is the easy part. You'll end up with a list of dozens or hundreds of keywords. Now you need a filter.

Sort by opportunity, not just volume. A keyword with 8,000 monthly searches and a difficulty of 72 is much less interesting than one with 800 searches and a difficulty of 22 — especially if you're not an established authority in that space yet.

Look for keyword clusters, not individual terms. If you see a competitor ranking for "project management for freelancers," "freelance project tracking," and "how freelancers manage clients," those are all probably covered by one piece of content on their site. You don't need three articles — you need one good one that's structured to capture the cluster.

Distinguish informational from commercial intent. A keyword like "how to choose project management software" is informational. "Best project management software for freelancers" is commercial. Both matter, but they require different content formats and sit at different stages of the buyer journey.

Prioritize gaps that match your existing content structure. If you already have strong coverage on a topic, a competitor gap in a subtopic of that area is easier to win than a fresh category you've never touched.

Building a Content Plan From the Gap List

Once you've filtered your keyword list down to realistic opportunities, map them to content types:

Assign each piece a target keyword (primary) and two or three supporting keywords (secondary). Write the brief before you write the content. The brief should note the search intent, the top-ranking competitors for that term, what they cover, and what angle you can take that they haven't.

The keyword competitive analysis guide walks through how to structure this gap-to-brief workflow in more detail.

A Note on Scale

If you do this once, you'll find a few dozen opportunities and build a short-term content plan. That's useful.

The problem is that your competitors are publishing continuously. The gap list from today is out of date in ninety days. The sites that win organically over time are the ones running this process on a schedule — quarterly at minimum — and publishing consistently against the gaps they find.

That's where the economics matter. A content agency can handle volume but often lacks the SEO precision. A freelancer can handle quality but not scale. Tools like Rankfill are built for this specific problem — mapping the full competitor keyword landscape for a site and identifying where organic traffic is being lost to competitors — which is useful if you want the gap analysis done at scale without doing it by hand every quarter.

For most sites, the right answer is a combination: understand the process well enough to evaluate the outputs, then decide how much of the execution to automate or outsource.

Frequently Asked Questions

How many competitors should I analyze? Three to five is enough for most sites. More than that and the data becomes noisy. Pick competitors who rank for the specific topics you want to own, not necessarily your direct business competitors — sometimes a content site or comparison site is outranking you, and they're the ones worth analyzing.

Do I need a paid tool, or can I do this free? You can get a partial picture free. Google's "site:" operator, manual browsing of competitor content, and Google Search Console for your own site give you something to work with. But you'll miss ranking position data, search volume, and difficulty scores — which are what turn a list of keywords into a prioritized plan. Most serious tools offer a free trial worth using.

How often should I run a competitor keyword analysis? Quarterly is a reasonable baseline. Do it more frequently if you're in a fast-moving market or actively publishing. See how to find and target competitor keywords for a repeatable workflow you can run on a schedule.

What if a competitor ranks for a keyword I don't think is relevant to my business? Skip it. Traffic that doesn't convert is a distraction. Filter your gap list for keywords that match your actual product, service, or content focus — not just anything a competitor happens to rank for.

How long before I see results after targeting a gap keyword? Expect three to six months for a new piece of content to fully index and rank. Competitive terms take longer. Terms with low difficulty on a domain with existing authority can move faster. Publish, wait ninety days, then check your Search Console impressions for that URL — it tells you if you're being seen at all, before you obsess over position.

What if multiple competitors all rank for a keyword I have no content for? That's a strong signal to prioritize it. If three or more competitors with similar or weaker domain authority than you are capturing that traffic, the gap is real and closeable. Start there. A deeper look at competitor keyword analysis can help you evaluate which of those consensus gaps are worth going after first.