Best Keyword Research Tool for Affiliate Marketing

Website: https://ahrefs.com

Best for: Deep link and keyword data

Starting price: $129 per month

Free plan: No

Pros: Deep link index and keyword data; Clear keyword difficulty scores

Cons: No free plan and no free trial; Lite at $129 is expensive for a beginner

Ahrefs is the reference tool for keyword and link research. Lite costs $129 per month, or $107.50 per month on annual billing, with Starter at $29 and Standard at $249 per month. The keyword database is deep, difficulty scores are clear, and the link index shows which pages link to any rival, so an affiliate can judge whether a keyword is winnable before writing a word. Traffic estimates and content gaps round out the research workflow.

The price is the barrier. At $129 per month, Lite costs more than four times what Keysearch charges, and Ahrefs offers no free plan and no free trial, so a beginner must commit before testing the data. The Starter plan at $29 is cheaper, but it limits reports and rows. Ahrefs suits an affiliate who already earns and needs the best data; it is too much for a first site.

Website: https://semrush.com

Best for: All-in-one SEO toolkit

Starting price: $139.95 per month

Free plan: Yes

Pros: Broadest toolkit, from keywords to content and ads; Free account for basic checks

Cons: Pro at $139.95 is costly for a solo affiliate; The interface has a steep learning curve

Semrush is the broadest toolkit here, covering keyword research, site audits, content ideas, rank tracking and ad research in one subscription. Pro costs $139.95 per month, or $117.33 per month on annual billing, with Guru at $249.95 and Business at $499.95. The free account allows limited checks, around 10 queries per day, which is enough to test the keyword data before subscribing. For an affiliate who also runs content and technical checks, Semrush replaces several tools at once.

The cost and the learning curve are the drawbacks. Pro at $139.95 per month is the most expensive entry on this list, and the interface packs in so many modules that a beginner can spend weeks learning it. A solo affiliate who only needs keyword research will find Mangools or Keysearch cheaper and simpler. Choose Semrush when the work spans keywords, content and site health, not for keyword lists alone.

Website: https://moz.com

Best for: Simple difficulty scores

Starting price: $49 per month

Free plan: Free trial (7 days)

Pros: Lowest entry price among the big three; Simple keyword difficulty scores

Cons: Trial is on Standard and Medium, not Starter; Smaller keyword database than Ahrefs or Semrush

Moz Pro is the simplest of the big three SEO suites. Starter costs $49 per month, and Moz publishes no yearly Starter price, so the monthly figure is the one to budget for. Keyword Explorer gives clear difficulty scores and search volume, and the interface is easier to learn than Semrush. For an affiliate who wants a straightforward answer to "can I rank for this keyword", Moz gives it without the extra modules.

The trial rules need care. Moz offers a 7-day trial on Standard and Medium, but the Starter plan has no trial, so a buyer of the cheapest tier cannot test it first. The keyword database is also smaller than the ones Ahrefs and Semrush maintain, which means rarer long-tail keywords may show no data. Moz suits a beginner who values clarity over depth.

Website: https://mangools.com

Best for: Budget full suite

Starting price: $37.70 per month (billed annually)

Free plan: Yes

Pros: Cheapest full suite here on annual billing; Five tools in one bundle

Cons: Daily lookup limits on Basic; Rank tracking updates weekly on Basic

Mangools bundles five tools, KWFinder for keyword research, SERPChecker, SERPWatcher, LinkMiner and SiteProfiler, plus AI Search Watcher, in one subscription. Basic costs $37.70 per month on annual billing, or $61 per month billed monthly, with Premium at $52.70 and Agency at $97.70 on annual billing. The prices rose on 1 November 2026, so older guides that list $29.90 per month are out of date. A free account with limits lets a beginner try the tools before subscribing.

The limits are the trade-off. Basic allows 100 keyword lookups per day and tracks 200 keywords, with rank updates weekly, so a heavy research day can hit the cap. Premium raises the limits to 500 lookups per day and 700 tracked keywords. For an affiliate who researches in batches rather than all day, Basic is enough, and at $452.40 per year it is the cheapest full suite here.

Website: https://neilpatel.com/ubersuggest/

Best for: Beginners and lifetime value

Starting price: $29 per month

Free plan: Yes

Pros: Lifetime option from $290; Low yearly price at $16 per month

Cons: Promotional prices change often; Fewer features than Semrush or Ahrefs

Ubersuggest is the budget-friendly option from Neil Patel, built for solo operators and small businesses. Individual costs $29 per month, or $16 per month billed yearly at $192 per year, with Business at $49 and Enterprise at $99 per month. A lifetime option starts at $290 for Individual, which pays for itself in about ten months against the monthly price. The free plan allows a few searches per day, around 3, which is enough to test the data. Keyword ideas, content ideas, site audits and rank tracking are all included.

The pricing page runs frequent promotions, and at check time it showed $12 per month on a promotional rate, so the live price may differ from the $29 list price. Confirm the figure before buying. Ubersuggest also has fewer features than Semrush or Ahrefs, with no link index of the same depth. It suits a beginner who wants solid keyword data at a low price, especially on the lifetime option.

Website: https://keysearch.co

Best for: Cheapest monthly entry

Starting price: $24 per month

Free plan: Free trial (7 days)

Pros: Cheapest monthly price here at $24; Simple interface for beginners

Cons: No free plan, only a 7-day trial; Smaller database than the big three

Keysearch is the cheapest monthly entry on this list. Starter costs $24 per month, or $20 per month billed annually at $240 per year, with Pro at $48 per month. The interface is simple: enter a keyword, see difficulty, volume and related ideas, and move on. That focus suits an affiliate who wants fast answers without learning a suite. The pricing sits on the homepage itself, because the standalone pricing page returns a 404.

There is no free plan, only a 7-day trial, so a beginner must subscribe to keep using it. The database is also smaller than the ones Ahrefs, Semrush and Moz maintain, which means some niche keywords may show thin data. For a new affiliate site on a tight budget, Keysearch gives the essentials at the lowest monthly price here.

Website: https://lowfruits.io

Best for: Low-competition keywords

Starting price: $29.90 per month

Free plan: Yes

Pros: Finds low-competition keywords other tools miss; Pay-as-you-go packs suit occasional use

Cons: Credit limits cap monthly research; Narrower scope than an all-in-one suite

LowFruits takes a different approach: instead of showing every keyword, it finds the weak spots where a new site can rank. Standard costs $29.90 per month, or $20.75 per month billed annually at $249 per year, with 3,000 credits per month, and Premium costs $79.90 per month. Pay-as-you-go packs start at $25 for 2,000 credits, which expire after one year, so an affiliate who researches in bursts can skip the subscription. Free keyword-idea searches exist for trying the tool.

The limits are the drawback. Credits cap how much research a subscription allows each month, and LowFruits is narrower than an all-in-one suite, with less depth on site audits and link analysis. It works best as a specialist tool alongside a broader suite, or as the main tool for an affiliate who targets low-competition keywords and needs few credits to find them.

First-year costs use annual billing where the vendor publishes it. Ahrefs and Semrush cost more than $1,200 in year one, while Ubersuggest, Keysearch, LowFruits and Mangools all stay under $500. The gap is the real decision: the big suites cost three to five times more, and a new affiliate site rarely needs their depth in year one.