we compared 8 online course platforms in common crawl's domain-level link graph. 27 non-platform domains link to all 8, while 78% of linking domains appear for only one subject.
how we pulled this
for each subject domain, we pulled the top 2,000 referring domains by authority from common crawl release Apr-Jun 2026 (cc-main-2026-apr-may-jun). we intersected those lists, then removed platform, cdn, social, and other non-editorial domains from the clean overlap counts.
the filter matters. hosting providers, cdns, url shorteners and the big social networks link to almost everything, so leaving them in would produce a universal list that is technically correct and useless for outreach. the counts below are after that filter unless a column says otherwise. everything here comes from the open common crawl webgraph, so you can reproduce it without a paid backlink tool.
subject domains
| domain | referring domains | cg authority |
|---|---|---|
| teachable.com | 30,940 | 64 |
| thinkific.com | 30,039 | 57 |
| kajabi.com | 15,015 | 53 |
| podia.com | 10,921 | 59 |
| learnworlds.com | 6,381 | 56 |
| gumroad.com | 48,751 | 63 |
| udemy.com | 52,998 | 63 |
| skillshare.com | 16,424 | 67 |
the overlap
across the 8 subjects, we found 11,435 unique linking domains. the clean universal set contains 27 domains.
| metric | value |
|---|---|
| unique linking domains | 11,435 |
| link to one subject | 78% |
| link to all 8 | 27 |
overlap distribution
| overlap | all domains | non-platform |
|---|---|---|
| link to all 8 | 33 | 27 |
| link to 7 | 36 | 28 |
| link to 6 | 61 | 55 |
| link to 5 | 128 | 124 |
| link to 4 | 244 | 239 |
| link to 3 | 579 | 569 |
| link to 2 | 1,382 | 1,373 |
| link to just 1 | 8,972 | 8,959 |
the distribution is the interesting part. most linking domains sit in the bottom row: they mention one product and never come back. the rows above it are where outreach lives, because a site that already covers several products in a category has an editorial reason to cover another one. a short universal list usually means the category is covered by a handful of directories, review sites and integration hubs rather than by a broad press base. a long one means the category has real editorial coverage, and the same sites are reachable for you.
the highest-authority sites linking to all of them are shopify.com, webflow.com and hubspot.com. those are the pages worth reading before you pitch anything, because they already decided this category is worth covering.
udemy.com carries the widest referring-domain profile of the set and learnworlds.com the narrowest, which is usually a function of age and press coverage rather than product quality. the gap between them is the practical opportunity: sites that cover the widest profile but not the narrowest are demonstrably willing to write about this category.
the category linkers
110 non-platform domains link to at least 6 of the 8 subjects. these repeat linkers are the sites most consistently connected to online course platforms.
highest-overlap category linkers
| domain | subjects | cg authority | links to |
|---|---|---|---|
| shopify.com | 8 | 80 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| webflow.com | 8 | 72 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| hubspot.com | 8 | 70 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| smallbiztrends.com | 8 | 67 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| podbean.com | 8 | 65 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| entrepreneur.com | 8 | 65 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| libsyn.com | 8 | 64 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| buzzsprout.com | 8 | 64 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| dev.to | 8 | 63 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| oberlo.com | 8 | 61 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| payhip.com | 8 | 61 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| mailerlite.com | 8 | 60 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| acast.com | 8 | 60 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| kit.com | 8 | 59 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| clickup.com | 8 | 59 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| activecampaign.com | 8 | 59 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| beehiiv.com | 8 | 58 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| thriveglobal.com | 8 | 57 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| influencermarketinghub.com | 8 | 57 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
| transistor.fm | 8 | 54 | teachable.com, thinkific.com, kajabi.com, podia.com, learnworlds.com, gumroad.com, udemy.com, skillshare.com |
the full data
download all 110 clean domains that link to at least 6 of the 8 subjects, ranked by overlap and authority.
check any of these domains
every domain in the tables above links to its full referring-domain profile. run your own domain to see who links to you.
run this for your own niche
pick your closest competitors, compare their referring domains, and keep the sites that link to several of them but not to you. sorting that gap by overlap and authority turns the same method into a specific outreach list.
the ordering is what makes it usable. a site that links to most of your competitors and not to you is a gap with an obvious pitch. the observed overlap gives you a specific reason to contact each site instead of relying on domain authority alone. work down from the top of the overlap column and stop when the reasons start feeling thin, because a pitch you cannot justify in one sentence is not worth sending.
one caveat worth stating plainly. common crawl is a sample of the web, not a census, so treat these counts as the shape of a link profile rather than an exact total. this study measures the Apr-Jun 2026 release, so rerun the comparison against later releases before treating any movement as a trend.
find the overlap in your market
run a backlink gap analysis on the same common crawl data used for this study.
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