--- title: "Backlink gap analysis tool for AI agents | SEO Skill" description: "Find the sites that link to two or more of your competitors but not to you, sorted by Domain Rating, from your own DataForSEO or Ahrefs key." canonical: "https://seoskill.dev/features/backlink-gap" language: "en" --- # Backlink gap analysis Ask your agent which sites link to two or more of your competitors and not to you. It compares up to 5 competitors from your own DataForSEO or Ahrefs account and lists the gap, highest Domain Rating first. Run it in a terminal, then sign in with Google. Or run it on your machine Installs the CLI, signs you in and adds the skill to your agents. Site crawls and Bing data run this way, on your own machine. A crawl fetches many pages, and Bing blocks our hosted server. ## What a backlink gap analysis finds A backlink gap analysis lists the websites that link to your competitors but not to you. Those sites already link out on your topic, so they are the warmest link building prospects you have. SEO Skill counts a site as part of the gap when it links to at least two of your competitors. One competitor's link can be a friendship, a sponsorship or chance. Two or more is a pattern, such as a comparison post, a tools list or a community that covers the whole category. Ahrefs' own [backlink gap guide](https://ahrefs.com/blog/backlink-gap-analysis/) draws the same line: sites that link to every competitor are high priority, and sites that link to two are next. ## Run a backlink gap in your agent in 3 steps 1. Add the hosted MCP server to Claude Code, Codex, Cursor, ChatGPT or any client with remote MCP, and sign in with Google. The commands are at the top of this page. 2. Save a [DataForSEO or Ahrefs key](https://seoskill.dev/docs/keys) on your account page. The provider bills you directly, and SEO Skill adds nothing on top. 3. Name your site and 2 to 5 competitors: ``` Run a backlink gap for example.com against example.org, example.net and example.io ``` The agent reads each site's referring domains, keeps the sites that link to two or more competitors and not to you, and sorts them by Domain Rating. A run with DataForSEO says what it cost: about $0.24 for a site and 3 competitors in November 2026. With Ahrefs it uses your API units. Prefer a terminal? `npm i -g seo` then `seo start` gives you the same gap as a command, with the key kept on your machine: ``` seo research link_gap --target example.com --competitors example.org,example.net,example.io ``` ## Pick competitors that win the searches you want A backlink gap is only as good as the competitors you compare. Pick the sites that rank for the searches you want, not the companies you meet in sales calls. If you are not sure who they are, ask first: ``` Which domains share the most keywords with example.com? Then show the top 10 for "invoice software" with each site's Domain Rating ``` Competitors lists the domains that rank for the same keywords as you, and a SERP shows who holds page one for one search. Sites a little stronger than yours make the best comparison. A gap against a site with 50 times your links tends to fill up with prospects that would never look at you (big publishers rarely link to the newcomer). The [SEO competitor analysis](https://seoskill.dev/features/seo-competitor-analysis) page walks through finding and grouping them. ## A real backlink gap: Umami against 3 analytics rivals We ran the gap for Umami, the open source web analytics tool, against Plausible, Fathom and Simple Analytics in November 2026, with DataForSEO and Domain Rating by [Ahrefs](https://ahrefs.com/). It found 90 sites that link to at least two of the three rivals and not to umami.is. The run cost $0.24. Of the 90 sites, 29 link to all three rivals, 14 have a Domain Rating of 50 or more, and 8 are both. Those 8 are where we would start. The top of the list: | Linking site | Domain Rating (links to) | | --- | --- | | iubenda.com | 94 (all 3) | | ycombinator.com | 91 (Plausible, Simple Analytics) | | beehiiv.com | 91 (all 3) | | kinsta.com | 89 (Plausible, Fathom) | | discourse.org | 83 (Plausible, Fathom) | | indiehackers.com | 82 (Plausible, Simple Analytics) | | spreadprivacy.com | 77 (all 3) | | sdf.org | 77 (all 3) | The other end matters too. 48 of the 90 sites have a Domain Rating under 10. Going by their names, many are tool directories and "alternatives to" lists. Some are worth a two-minute submission. Few are worth an outreach email. Then we swapped the roles. With Plausible as the target and Umami, Fathom and Simple Analytics as competitors, the gap was 13 sites. Most strong sites that link to two of Plausible's rivals already link to Plausible, which is what a category leader's link profile looks like. A short gap is still a finding. ## Read the gap by overlap first, then Domain Rating Each row names the linking site, its Domain Rating and which of your competitors it links to. A site that links to all your competitors covers the category on purpose, so it is the likeliest to add you. Ask your agent to put those first: ``` From that backlink gap, list the sites that link to every competitor, then the ones with Domain Rating 50 or more, and tell me what each site is ``` Domain Rating tells you how strong a site's own links are, not whether it would link to you. In the Umami gap, a cookie consent company and Y Combinator sit at the top. Whether either is a real prospect depends on the page that carries the link, so open the site before you write to it. URL shorteners, link lists, and coupon or site-stats directories link to almost every site, so the gap leaves them out and names each one. The Umami run left out one, a subdomain finder. ## See which competitor pages earn the links The gap names sites. Two more research actions show what earned the links. Backlinks lists a competitor's referring domains, strongest first, with how many links each one sends and when it first linked. Pages by backlinks lists the competitor pages that most sites link to: ``` Which pages on example.org have the most referring domains, and which sites link to example.org most often? ``` If a competitor's most linked page is a free tool, a pricing study or an open dataset, that is the kind of page the sites in your gap link to. A page like it on your site gives you something to point them at. ## SEO Skill and the Semrush Backlink Gap tool compared The [Semrush Backlink Gap tool](https://www.semrush.com/kb/773-backlink-gap) compares up to five domains at once, yours included, and its Best tab shows the domains that link to all your competitors but not to you. It is part of Semrush's SEO toolkit, with daily limits set by your plan. | Question | SEO Skill | | --- | --- | | How many sites? | Yours and 2 to 5 competitors. | | Which sites count? | Sites that link to two or more competitors and not to you. | | Sorted by | Domain Rating by Ahrefs, highest first. | | Where it runs | In your agent, or as a command in your terminal. | | What it costs | Your own DataForSEO or Ahrefs usage, about $0.24 a run with DataForSEO. | If you already pay for Semrush and work in its interface, its tool does the job. SEO Skill suits you if you want the gap inside the agent that writes your outreach list, next to your own Search Console data. ## What a capped backlink list cannot prove The gap reads each site's top 1,000 referring domains, strongest first. When a site has more than that, the gap stops at the lowest authority it read and says so, instead of guessing below it. Both analytics runs stopped there, because at least one of the four sites has more than 1,000 referring domains. So a site missing from the gap may still link to a competitor below that line, and a site in the gap may link to you somewhere the provider has not crawled. Link counts and Domain Rating are provider estimates, and no outside index sees every link Google sees. The gap also compares whole domains and names the linking site. To find the page that carries the link, open the site or ask your agent to search it. ## Read more [ ### seo research Every research action, including the link gap, with its inputs and CLI flags. seo research docs](https://seoskill.dev/docs/research)[ ### API keys Add a DataForSEO or Ahrefs key to the hosted MCP or the CLI. API keys docs](https://seoskill.dev/docs/keys)[ ### Backlink checker See who links to any domain or page in your browser, with no account. Free tool](https://seoskill.dev/tools/backlink-checker)[ ### Domain Rating checker Check the Domain Rating of up to 10 sites at once, for free. Free tool](https://seoskill.dev/tools/domain-rating-checker)[ ### AI keyword research tool Find the competitors that win your searches before you compare their links. Keyword research](https://seoskill.dev/features/keyword-research)