Your competitors keep ranking for topics you never wrote about. Which ones are worth chasing?
A content gap analysis answers that: list what rivals rank for and you don’t, then keep what you can win. Start free with Search Console and a rival’s sitemap. Pay for Semrush Keyword Gap (about $140 a month) once you need search volumes.
The catch? A raw gap list is mostly noise. Here’s how to cut it into topic clusters you can publish.
Semrush and Similarweb links are affiliate links. They don’t change our picks.
What does a content gap analysis actually find?
It finds three kinds of hole in your site. Only one of them means writing a new post.
| Gap type | What it looks like | The fix |
|---|---|---|
| Missing topic | Rivals rank for it; you have no page | A new post, planned inside a cluster |
| Weak page | You’re on page two; every rival sits higher | Update the page you have |
| Format gap | You wrote a review; searchers want a tutorial | A new page in the winning format |
Most people chase only the first row. That’s a mistake. A weak page already has links, age and Google’s attention, so lifting it from position 14 to 6 usually beats ranking a new post.
How we put this guide together
We ran the free sitemap method for real: DroidCrunch’s own sitemap against a WordPress tutorial blog’s. The output below is ours.
We didn’t run fresh Semrush or Similarweb reports for this one. Those steps follow each tool’s help docs. Every price was checked on 27 October 2026.
Who should you compare yourself against?
Compare against the sites that beat you in search, not the brands you think of as rivals. They’re often different lists.
A SaaS review blog might lose its clicks to a forum thread and two niche blogs, not the big publisher it worries about. Google your five most important keywords. Whoever keeps showing up is your search competitor.
Then pick three or four of a similar size. Why not the giants? Compare a 500-post blog with a 50,000-page publisher and the gap list fills with topics you can’t win this year. Our competitor analysis tools roundup covers the tools that build this list for you.
The free method: Search Console, sitemaps and the results page
You can run a useful content gap analysis for $0. It’s slower and shows no search volume. It still finds real gaps.
A free content gap analysis in five steps
No paid tool needed. Budget an afternoon for your first run.
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Step 1 of 5
Export your own queries from Search Console
Open Performance, set the date range to the last 3 months and export the Queries tab. The screen and export stop at 1,000 rows, so filter by a folder or topic if your site is big.
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Step 2 of 5
Mark your weak pages
Sort by impressions and look for queries in positions 8 to 20. Those are pages Google already tests for the topic. Each one is a weak-page gap you fix by updating, not by writing.
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Step 3 of 5
Pull each competitor's post list from their sitemap
Most WordPress sites publish one at
/sitemap_index.xml(Yoast and Rank Math) or/wp-sitemap.xml(WordPress core). The script below compares their slugs with yours. -
Step 4 of 5
Check each candidate topic on Google
Search it. If the top results are forum threads or thin pages, that’s a gap you can win. If they’re ten big brands, park it.
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Step 5 of 5
Mine People Also Ask for the sub-questions
Open every People Also Ask box on the results page and copy the questions. They become H2s or FAQs in the page you write, so you close the gap in one go.
Step 3 is slow by hand, so we wrote a script for it.
import re, sys
from collections import Counter
from urllib.request import Request, urlopen
UA = {"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64)"}
STOP = set("a an and the for to of in on with your you how what is are best vs top free guide review "
"reviews tips ways why can do does using use from it its this that my".split())
def urls(sitemap):
xml = urlopen(Request(sitemap, headers=UA), timeout=30).read().decode("utf-8", "ignore")
locs = re.findall(r"<loc>\s*(.*?)\s*</loc>", xml)
if "<sitemapindex" in xml: # an index: follow the post sitemaps only
out = []
for child in locs:
if "post-sitemap" in child or "posts" in child:
out += urls(child)
return out
return locs
def topics(sitemap):
words = Counter()
for u in urls(sitemap):
slug = u.rstrip("/").rsplit("/", 1)[-1]
words.update({w for w in slug.split("-") if w not in STOP and not w.isdigit() and len(w) > 1})
return words
you, them = topics(sys.argv[1]), topics(sys.argv[2])
print(f"{'topic':<18}{'them':>6}{'you':>6}")
for word, n in them.most_common(400):
if n >= 3 and you[word] == 0: # they wrote 3+ posts on it, you wrote none
print(f"{word:<18}{n:>6}{you[word]:>6}")Pass your sitemap first and the rival’s second: python3 sitemap_gap.py https://yoursite.com/sitemap_index.xml https://rival.com/sitemap_index.xml. It needs only Python 3.
What it found when we ran it
Our sitemap listed 562 posts and the rival’s listed 1,308. The script flagged 274 words the rival used in three or more slugs and we never used.
Most were noise: site (34), development (28), business (25), add (19). Only six of the top 40 were real topics:
| Topic word | Their posts | Our posts | Real gap? |
|---|---|---|---|
| php | 35 | 0 | Yes, but off-strategy for us |
| shopify | 15 | 0 | Yes |
| wix | 14 | 0 | No: we have a Webflow vs Wix post |
| squarespace | 11 | 0 | Yes |
| siteground | 10 | 0 | Yes |
| speed | 10 | 0 | Partly: we cover it inside reviews |
Look at the Wix row. Our comparison is live, but our sitemap file hadn’t picked it up. Sitemaps can lag, so check the newest date inside one before you trust the diff.
Our take: the free method shows which topics a rival covers, not how much traffic each brings. Use it for a shortlist, then check each topic on Google.
How to run a content gap analysis in Semrush
Semrush’s Keyword Gap tool compares your domain with up to four competitors and sorts every keyword by who ranks. It’s the quickest route to a gap list with volume and difficulty attached.
Semrush Keyword Gap, step by step
Plan on about an hour for the first full pass.
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Step 1 of 6
Enter your domain and up to four competitors
Use your search competitors from earlier. Leave the keyword type on Organic and pick the country you sell to.
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Step 2 of 6
Open the Missing tab first
Missing lists keywords every competitor ranks for in Google’s top 100 and you don’t. When all of them cover a topic, demand is proven.
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Step 3 of 6
Then open Untapped
Untapped is looser: at least one competitor ranks and you don’t. It’s bigger and noisier, but it’s where single-rival ideas hide.
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Step 4 of 6
Check Weak last
Weak lists keywords where you rank below every competitor. These are your update jobs, so send them to whoever owns those pages.
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Step 5 of 6
Filter hard before you export
Set KD% under 30 (Semrush calls 0 to 29 very easy and easy), volume 50 or more, and exclude rivals’ brand names. Add an intent filter for informational or commercial searches.
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Step 6 of 6
Export and group into clusters
Export to CSV, then group the keywords by search intent (next section). On Pro+ or higher, Topic Research shows the subtopics and questions around each cluster.
Now the money. Keyword Gap comes with the SEO plan: about $140 a month, or $117.33 a month billed yearly.
Topic Research is the catch. The SEO plan gets two searches, ever. Unlimited use starts on Pro+ at $299 a month ($248.17 billed yearly). The separate Content Toolkit, with its Topic Finder, costs $60 a month billed yearly.
Our take: for a one-off audit, use the SEO plan and group the clusters yourself. Our Semrush pricing breakdown shows which tier fits an agency, and the full Semrush review covers the rest of the suite.
Already doing keyword research there? The gap list feeds straight into the workflow in our Semrush keyword research tutorial.
How Similarweb’s keyword gap differs
Similarweb measures traffic share, not rankings. Its gap report shows who actually gets the clicks on each keyword, from the last 28 days of data.
That changes what you find. A rival can rank fourth and still take most clicks with a featured snippet. Semrush shows the ranking. Similarweb shows the outcome.
The workflow is short:
- In Search Competitors, compare up to four sites. The Search Overlap Score shows who shares the most keywords with you.
- In Website Keywords, enter your own site first, then click + Add site for keyword gap. The filters judge everything from the first site’s point of view.
- Open Opportunities (they get traffic, you don’t) and Losses (you get less traffic than them).
- Try the High Traffic Opportunities filter: positions 6 to 20, solid volume, and a zero-click rate of 60% or lower.
That last filter is a ready-made weak-page finder. It also screens out keywords where most searches end on the results page.
The cost hurts. Keyword gap needs the Competitive Intel & SEO & AEO plan: $399 a month, or $333 billed yearly, for one user. That’s nearly three times Semrush’s SEO plan.
So who’s it for? Pick Similarweb if you also want competitors’ traffic sources, referral sites and audience data in the same place. Our Similarweb review walks through those reports. If keyword gaps are all you need, Semrush does the job for less.
Which method should you use?
Pick by budget and by the question you’re asking.
| Method | Cost | Best for | Blind spot |
|---|---|---|---|
| Search Console + sitemaps | Free | New blogs, one-off audits, weak-page fixes | No volume or competitor traffic data |
| Semrush Keyword Gap | About $140 a month | Most blogs and agencies | Rankings, not clicks |
| Similarweb keyword gap | $399 a month, or $333 billed yearly | Teams that also need traffic and channel data | Price, and one user per plan |
| Clearscope Topic Exploration | $129 a month | Content teams that write and optimize in Clearscope | Not a competitor keyword comparison |
For most blogs, the free method plus one month of Semrush covers a full audit. Cancel once the cluster plan is built.
How do you turn a gap list into clusters you can win?
Group keywords by what the searcher wants, then give each group one page. Most gap guides skip this step. It’s where the value is.
A gap export of 300 keywords isn’t 300 posts. Many keywords share one intent. wix vs squarespace, squarespace or wix and is wix better than squarespace all want the same comparison.
Here’s a quick test. Google both keywords. If four or more top-10 results match, treat them as one topic and one page. Semrush runs a similar check: its Related % shows how many top-20 results two keywords share.
Then arrange the pages into a cluster. One pillar page covers the broad topic. Four to eight supporting pages each answer one narrow question, and they link to the pillar and back.
Take the website-builder gap our script found. The pillar would be a guide to choosing a builder. Shopify vs Squarespace, a Squarespace review, a Shopify pricing post and our existing Webflow vs Wix piece would support it.
Want to measure how much of a topic you already own? Clearscope’s Topic Exploration clusters hundreds of queries into subtopics and, once your site is connected, shows your share of voice in each. Essentials costs $129 a month with 20 Discoveries. Our Clearscope review covers its writing side.
Clusters help with AI answers too, because Google’s AI Overviews also draw on related follow-up searches. Our guide to ranking in Google AI Overviews shows how to check those.
Five mistakes that waste a gap analysis
- Chasing rivals’ brand keywords. “[Competitor] login” will never rank for you. Filter brand names out before you export.
- One page per keyword. Ten near-duplicate posts compete with each other. Group by intent first.
- Ignoring Weak. Updating a page in position 12 is a week’s work. A new post can take months to rank.
- Comparing against giants. Their gap list is their authority, not your opportunity.
- Running it once. Rivals publish every week. Re-run the gap each quarter and diff it against the last export.
Frequently asked questions
What’s the difference between a keyword gap and a content gap analysis?
A keyword gap is the raw list of keywords rivals rank for and you don’t. A content gap analysis goes further. It groups those keywords into topics, checks which ones you can win, and decides whether each needs a new page or an update.
Is Semrush’s free plan enough for a content gap analysis?
Not really. The free account allows 10 reports a day, shows about 10 rows per report and doesn’t export. That’s enough to see how Keyword Gap works, not to build a cluster plan. Semrush’s 7-day trial on a paid plan suits the real audit.
Can I do a content gap analysis with Ahrefs instead?
Yes. Ahrefs replaced its old Content Gap tab with a Competitive Analysis report. It works the same way: enter your site and competitors, and it lists keywords they rank for and you don’t. The filtering and clustering steps above apply unchanged.
Does a content gap analysis work for a brand-new site?
Partly. A new site ranks for almost nothing, so every competitor keyword shows up as a gap. Start from rivals’ top pages instead and filter for low difficulty. Build one complete cluster before you widen the comparison.
How often should I run a content gap analysis?
Once a quarter suits most blogs. Competitors publish all the time, and rankings shift with each core update. Save every export with its date. The next run then shows what changed, so you don’t start from scratch.
Should I copy the structure of a competitor’s page that ranks?
Copy the format, not the content. If every top result is a step-by-step tutorial, write a tutorial. Then add what theirs lacks: your own test, a worked example, an honest catch. A copied page gives Google no reason to swap the winner out.
How do I find content gaps in ChatGPT and AI search answers?
Ask the AI tools your buyers’ questions and note which sites they cite. Semrush’s AI visibility features and Clearscope’s query tracking automate this. The gaps are often sub-questions your page never answers, which our guide to generative engine optimization covers.
Start with the free version this week
A content gap analysis is only useful if it ends in a short, ordered list of pages. Start free: export Search Console, run the sitemap script against three rivals and fix weak pages first. Add Semrush Keyword Gap when you need volume and difficulty. Add Similarweb only if you also want traffic data.
One warning: don’t publish one post per keyword. Group them into topic clusters first. Your next step? Pick three search competitors tonight and run the script.
