How we make this list: we compare pricing pages, product documentation and public user reviews. Ratings come from G2, Capterra or Trustpilot, with the date we checked them.
Key takeaways
- Ahrefs Content Gap is the reference feature in this category, comparing up to several domains against yours in one report.
- Semrush Keyword Gap matches it and adds paid search gaps beside the organic ones.
- SpyFu runs the same comparison for $39 a month, the cheapest serious entry here.
- SE Ranking and Moz Pro bundle gap reports inside broader suites most teams buy for other reasons.
- MarketMuse works at topic level inside your own inventory, finding thin coverage rather than rival keywords.
Quick comparison
| Tool | Best for | Starting price | Free plan |
|---|
 Ahrefs | The reference content gap report | $129/month | Yes |
 Semrush | Keyword gaps across organic and paid search | $139.95/month | Yes |
 SE Ranking | Gap analysis inside an agency suite | See website | No |
 SpyFu | Budget gap analysis with ad history | $39/month | Yes |
 Moz Pro | Gap checks for teams already on Moz | See website | No |
 MarketMuse | Topic gaps inside your own content | See website | No |
 Frase | Turning a gap into a brief for one article | $49/month | No |
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The best tools for content gap analysis in 2026
#1Ahrefs
Best for: The reference content gap report4.5/5 on
G2 (717 reviews, checked Oct 2026)
Visit ahrefs.com
Starting price$129/month
Free planYes
Ahrefs Content Gap is the feature most people picture when they say content gap analysis. Enter your domain and up to several competitors, and it returns the keywords they rank for that you do not, sortable by volume and filterable by where each rival sits. Because it runs on Ahrefs' crawl, the same session can check the backlink profile of the pages filling the gap, which separates topics you could win with one good article from topics defended by a wall of links.
The discipline is in the filtering. An unfiltered report against three large competitors can run to six figures of keywords. Filter to realistic positions, exclude brand terms and near duplicates, and the export becomes a quarter's editorial plan. That workflow, more than any single feature, is why Ahrefs leads this list.
What we like- Content Gap compares your domain against several competitors in one view, filters by position, volume and intersection keep the list usable, the backlink index shows which gap topics also earn links, free webmaster tools verify your own side of the comparison
Watch out for- Full plans start at $129 a month with credit based usage on top, gap reports can return overwhelming lists without tight filters, no paid search data in the gap view
#2Semrush
Best for: Keyword gaps across organic and paid search4.4/5 on
G2 (4,035 reviews, checked Oct 2026)
Visit semrush.com
Starting price$139.95/month
Free planYes
Semrush's Keyword Gap is Ahrefs' closest rival and beats it in one respect: it runs the comparison on paid search too, so a topic a competitor buys but you have never targeted organically shows up in the same session. The overlap diagram, splitting keywords into shared, missing, weak and untapped, is the clearest visual summary of a competitive position in any tool here.
For content planning, the path from gap to brief is short: a missing keyword opens into topic clusters and questions, and the same account tracks whether the article you wrote closed the gap. The costs are the familiar Semrush ones. The entry plan is $139.95 a month, limits bite quickly, and teams end up budgeting for the tier above the one in the advert.
What we like- Keyword Gap compares up to five domains across organic and paid results, overlap views show shared, missing and untapped keywords clearly, Backlink Gap runs the same comparison on referring domains, topic research tools carry a gap into a content plan
Watch out for- Full value needs the higher tiers once projects and seats grow, data volume makes the interface heavy for occasional users, free account limits the depth of every report
#3SE Ranking
Best for: Gap analysis inside an agency suite4.7/5 on
G2 (1,606 reviews, checked Oct 2026)
Visit seranking.com
Starting priceSee website
Free planNo
SE Ranking folds gap analysis into the competitor research module of a suite agencies buy mainly for rank tracking. Look up a rival and it lists the keywords driving their traffic, including the ones absent from your own profile, which is the gap report in everything but name. For an agency reporting to clients, having the gap and the subsequent ranking movement in one tool keeps the story simple: here is what we found, here is what we closed.
Its index depth is the honest limitation, especially outside major markets and languages, and its pricing has been restructured, which is why this entry says See website. For teams already paying for SE Ranking, the gap features are a reason to stay. For teams buying purely for gap depth, Ahrefs' crawl is the stronger purchase.
What we like- Competitor module returns rival keywords you do not rank for, gap results feed directly into its rank tracker, AI visibility gaps now tracked beside classic search, agency reporting wraps findings for clients
Watch out for- Index is smaller than Ahrefs or Semrush for niche markets, pricing structure changed recently, so confirm the current plan, no free plan beyond a trial
#4SpyFu
Best for: Budget gap analysis with ad history4.6/5 on
G2 (518 reviews, checked Oct 2026)
Visit spyfu.com
Starting price$39/month
Free planYes
SpyFu's Kombat feature lines your domain up against two competitors and sorts keywords into the ones everyone ranks for, the ones only rivals hold, and the ones you hold alone. That middle list is your gap, and SpyFu delivers it for $39 a month with no search caps, a third of the entry price of the suites above it. Its paid search archive adds a useful angle: a keyword a rival has bought for years is a keyword that converts, which reorders a gap list better than volume alone.
The compromises are coverage and polish. International data is thinner, the link side is basic, and the exports need cleaning. For a US focused business doing its own content planning, though, SpyFu covers the essential gap workflow for the least money here.
What we like- Kombat tool compares domains and lists keywords you miss, every comparison includes the paid search side at no extra tier, archive reaching back to 2006 shows gaps opening and closing over time, unlimited searching on paid plans suits heavy research sessions
Watch out for- Strongest data is US only, backlink data is thin beside Ahrefs, interface and exports are dated compared with the suites
#5Moz Pro
Best for: Gap checks for teams already on Moz4.3/5 on
G2 (608 reviews, checked Oct 2026)
Visit moz.com
Starting priceSee website
Free planNo
Moz Pro approaches gaps through its keyword and link tools rather than one branded report: compare your domain with a rival's, read the overlap, and use Domain Authority to judge which missing topics are realistic fights. For the many teams who learned SEO on Moz metrics, that shared scale is a practical advantage, because a gap list sorted by winnability beats one sorted by volume.
Buy it as part of the suite, not for gap analysis alone. Its index trails the leaders, and its pricing tiers have been revised, hence See website here. Inside a Moz subscription the gap workflow is perfectly serviceable. Starting from zero purely to find content gaps, Ahrefs or SpyFu answer more directly at their prices.
What we like- Keyword Explorer shows rival keywords and overlap against your domain, Domain Authority gives a shared scale for judging how hard a gap is to close, campaign structure keeps gap findings beside rankings and audits, gentle interface for teams new to SEO tooling
Watch out for- Index is smaller than Ahrefs and Semrush, plan tiers and prices have changed, so the entry figure needs checking live, gap reporting is less direct than a named gap feature
#6MarketMuse
Best for: Topic gaps inside your own content4.6/5 on
G2 (216 reviews, checked Oct 2026)
Visit marketmuse.com
Starting priceSee website
Free planNo
MarketMuse flips the direction of gap analysis. Instead of asking which keywords rivals rank for, it inventories everything you have published, models the topics your site should own, and shows where your coverage is absent or too thin to compete. Its difficulty scoring is personalised to your domain's strength on each topic, which fixes the common failure of gap lists full of fights you cannot yet win.
That inward view pairs well with one of the rival facing tools above rather than replacing it. Pricing is by quote and the platform suits organisations publishing at scale. A small site will get its gaps from Ahrefs or SpyFu for less. A content operation with hundreds of pages will find MarketMuse's inventory view is the one that stops duplication and drift.
What we like- Inventories your own pages and scores topical coverage against the field, finds thin pages to deepen as well as topics to create, personalised difficulty weighs your site's authority per topic, briefs generated from the analysis carry the depth targets
Watch out for- Quote led pricing aimed at content teams with budget, looks inward more than at named rivals' keyword lists, value depends on connecting your analytics and Search Console data
#7Frase
Best for: Turning a gap into a brief for one article4.8/5 on
G2 (311 reviews, checked Oct 2026)
Visit frase.io
Starting price$49/month
Free planNo
Frase operates at the sharp end of gap analysis: a single article. Give it the keyword you want to win and it reads the pages currently ranking, extracts the headings, topics and questions they all cover, and shows you what your draft is missing against them. For a writer, that page level gap is more actionable than a domain report, because it lands directly in the outline.
It is a complement, not a competitor, to the suites above. Frase holds no index and cannot tell you which keywords to target in the first place; it assumes the gap has already been chosen, by Ahrefs, Semrush or SpyFu, and then helps you close it. At $49 a month for that final step, content teams publishing weekly will recover the cost in briefing time alone.
What we like- Pulls the top ranking pages for a keyword and maps their shared topics, headings and questions, the gap becomes an outline and brief in the same session, AI drafting inside the brief speeds the writing step, priced for individuals and small teams
Watch out for- Works one keyword at a time, so it cannot map a whole domain gap, no backlink or index data of its own, document limits on entry plans meter heavy use
How we chose
A tool qualified by offering a direct domain against domain comparison, a named gap feature, or an inventory analysis that surfaces missing topics with evidence. Index depth was weighted heavily, because a gap report can only find what the crawl has seen. Prices were checked on vendor pages in October 2026, and entries say See website where the vendor sells by quote or has recently restructured its plans, rather than printing a figure that may already be wrong. Tools that merely list your own keywords, with no comparison against anyone, were left out.
How to run a gap analysis that produces work, not a spreadsheet
Filter before you export. Restrict rivals to the positions that matter, usually the top twenty, set a volume floor your business can feel, and remove brand terms and topics outside your offer. A list of three hundred plausible articles beats a list of thirty thousand keywords every time, because a human has to choose from it.
Score the gaps by more than volume. Check what the ranking pages look like: a gap filled by thin forum posts and outdated guides is open ground, while a gap filled by a rival's flagship research is a campaign, not an article. SpyFu's ad history adds a commercial test, since a keyword competitors pay for year after year is one that makes money.
Close the loop in your tracker. Tag every article you publish from the analysis, then re-run the same comparison in a quarter. The second report, showing which gaps closed and which new ones opened, is the document that justifies the tool's subscription and the team's time.
Frequently asked questions
What is a content gap analysis?
It is a comparison between your site and competitors that lists the keywords, topics and pages they have and you lack. Tools run it by comparing ranking data across domains. The output is a work list for content planning, ordered by the size of the opportunity and how hard each topic is likely to be to win.
How many competitors should I compare against?
Three is the working number for most sites: your closest rival, the biggest player in the niche and one fast riser. Comparing against one gives a narrow list; comparing against ten produces noise and topics that belong to businesses unlike yours. Ahrefs and Semrush both let you intersect several rivals to find gaps every one of them covers.
Are keyword gaps and topic gaps the same thing?
No. A keyword gap is a specific search term a rival ranks for that you do not. A topic gap is a subject your site has not covered, or covers too thinly to compete, which MarketMuse style inventory analysis finds. Good planning uses both: topics set the calendar, keywords shape each article.
Can I run a content gap analysis for free?
Partly. Ahrefs and Semrush free accounts show samples of their gap reports, and SpyFu's free searches preview its comparisons. A full export needs a paid plan at one of them. The cheapest full route here is SpyFu at $39 a month, which you can cancel once the quarterly analysis is done.
How often should I repeat a gap analysis?
Quarterly suits most teams: often enough to catch a rival's new push, rare enough that the previous list got written. Re-run sooner after a site restructure, a new competitor entering the market, or a sharp traffic change you cannot explain from your own changes.
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Is your product missing or out of date?
We review this list regularly. Vendors can request a listing, send updated pricing or ask about featured placement.
Shihab Mia · Founder, Rankite
Shihab has 5+ years in B2B and SaaS SEO. He writes Rankite's software buying guides from pricing pages, documentation and public user reviews. More about Shihab.