Comparison
Free backlink checker sites, side by side
A directory owner needs two things from a checker: a quick look at one tool, and a way to score the whole list. Few sites do both, so compare them on that.
SEO Tools AI research team ·
Four options, six questions
| Question | Ahrefs | Moz | Majestic | Our API |
|---|---|---|---|---|
| Quick look at one domain | Free checker page | Link Explorer, limited free use | Site Explorer, limited free use | Free domain and overview calls |
| Own score name | Domain Rating | Domain Authority | Trust Flow, Citation Flow | DR, public formula |
| Scripting | API units inside a subscription | API plans available | API plans available | Prepaid credit, from $0.10 per 1,000 calls |
| Bulk scoring | By plan | By plan | By plan | 2,000 domains per bulk_dr call |
| Keywords and rank tracking | Yes, a full suite | Yes | Not the focus | No |
| Data freshness | Crawled continuously | Varies by product | Varies by product | Roughly monthly refresh |
What the table does not say
Ahrefs sells API units inside subscriptions, from $129 a month for 200,000 units, with at least 50 units per request. That is fine for an agency. It is awkward for a directory that scores 3,000 domains once a month and then sits idle.
For keywords, rank tracking and a crawl that is fresh every day, Ahrefs or Semrush is the fuller product, and we say so plainly. Our API does one narrow job: link data at a low per-call price.
Two scores for the same domain will differ. That is normal. Each vendor measures its own graph, so pick one metric for the whole directory and keep it for every listing, otherwise your sort order mixes apples and pears.
A column that shows Moz DA for some rows and DR for others is not a ranking. If you must cite another vendor, add it as a separate labelled column.
How to test a checker in ten minutes
Pick five domains you know well: a giant, a mid-sized SaaS, a niche tool, a brand-new site and your own. Run each through every checker you are considering.
Do not expect equal numbers. Look at the order instead. If all checkers put the giant first and the new site last, they agree on the shape, and the details are vendor noise.
Then look beyond the score. Referring domains and anchors are the parts a reader can verify, so a checker that hides them is asking for blind trust. See the glossary if a term is unfamiliar, and the sync recipe when you are ready to batch.
A short decision tree
If you list fewer than 50 tools, use any free checker by hand and skip the engineering.
If you list 50 to 300 and want a score on each, call bulk_dr from a spreadsheet script once a month.
If you also sell keyword research or rank tracking, you probably already pay for a suite, and the suite API may be enough for you.
If you run a comparison site with thousands of pages, the per-call price is what matters, so work out your monthly call count first. The budget walkthrough does exactly that.
Checker questions
Which backlink checker sites are really free?
Several offer a limited free lookup, usually one domain at a time with capped rows. That suits a single check. Our domain, overview, stats and suggest actions are free with no key, but heavier actions use credits from your balance.
Can I use two checkers for the same listing?
You can, as long as each stays in its own labelled column. Showing both a DR and a DA invites readers to cross-check, which is healthy. Mixing them in one sort order is the mistake to avoid.