Start a backlink-tool comparison with the question you're trying to answer. You might need to analyze a large set of links, understand a site's history, or find publishers to approach. Check whether the data and available operations support that job, alongside the advertised index size.
Imagine your backlink total goes up. To understand why, you need the referring pages and collection dates. If you want a similar link from one of those publishers, you'll also need to read the page and find out how businesses get included.
OppAlerts publishes this guide and is included in it. We haven't measured the indexes against one another. Vendor details come from September 2026 research.
Check what each allowance lets you do
The researched Ahrefs plans at $129, $249, and $449 include 100,000, 500,000, and 1.5 million crawl credits. Those credits cover site crawling, so they don't tell you how many stored backlinks you can analyze. API and MCP access start at Lite. Additional users cost $40, $60, or $80 monthly by tier.
Majestic measures analyzable backlinks with allowances of one million, 20 million, and 100 million AnalysisResUnits. Its Fresh Index can be checked several times daily and is separate from its Historic Index. Those allowances are relevant when your task involves large numbers of link records.
Semrush's researched $139 to $549 range, SE Ranking's dated $129 and $279 packages, and Serpstat's plans from $50 combine backlink research with keyword tracking and audits. Serpstat lists 100, 500, 1,000, and 5,000 daily site, keyword, and link research searches. Work out whether you need searches, crawled pages, or analyzed links before comparing the totals.
Choose the history your research needs
The researched Ahrefs plans include six months, two years, and five years of history. Majestic separates fresh and historical data. Several reviewed platform pages didn't specify retention, so ask what remains available if you downgrade before relying on it for long-term research.
OppAlerts provides monthly PageRank records and charts from July 2017 where data is available. The charts show Domain and Host series. Host uses the larger available bare-host or www-host value each month. These measurements describe the link graph rather than counting backlinks.
Two sites can have the same value this month and very different histories. Open the series to see what you'd like to investigate further. PageRank history and PRoT explains the monthly values and how they're added into an accumulated measure.
Follow the link into a possible opportunity
Semrush, Ahrefs, and OppAlerts offer link-gap comparisons with selected competitors. Each uses its own records, matching rules, and host handling, so try the same sites in each tool. The guide to choosing competitors explains how that selection changes what you find.
If a resource page links to a competitor, open it to see whether it accepts relevant additions. Ahrefs Brand Radar also offers web-mention tracking and prospecting. If you already use it, try those functions as part of the task.
OppAlerts Site Info provides collected contact pages, emails, phone numbers, and social profiles, without verifying whether they still work. Its Prospect Index searches opportunity types such as contributions, resource lists, podcasts, directories, awards, and speaking submissions. You can use it to find prospects beyond the links already recorded for your competitors.
Read the current resource page to check its subject and inclusion requirements. OppAlerts doesn't audit sites or claim a larger index, and its API and MCP operations are read-only. Test bulk analysis with the data operations you need, and publisher research through to the actual page. The prospecting comparison covers that next step.
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