SEO tools help you understand and improve how a website performs in search results. The main jobs are keyword research, backlink analysis, rank tracking, technical site audits and content optimization, and most tools also report on competitors' rankings and estimated traffic.
The figures they show, such as search volume, traffic and keyword difficulty, are estimates from each vendor's own models, so use them to compare options rather than to forecast. All-in-one suites cover most of these jobs in one subscription, while specialist tools go deeper on one, such as crawling a site for technical errors or optimizing a single page. Check what an extra user costs before choosing a suite: Ahrefs and Semrush charge $40 to $100 a month for each one and Moz $49, and projects and reports are often capped by plan.
At a glance
| Tool | Best for | Starting price | Free trial |
|---|---|---|---|
 Ahrefs | Best for SEO teams and agencies that research competitors' backlinks and keywords | Free plan | No |
 Screaming Frog | Best for technical SEOs who audit large or JavaScript-heavy sites from their own computer | Free plan | No |
 Surfer SEO | Best for content teams that brief writers and check each article against the search results | $49/mo | 7 days |
 Semrush | Best for marketing teams that want daily rank tracking and competitor research in one login | Free plan | 7 days |
 Moz Pro | Best for in-house marketers tracking a few sites' rankings and crawl issues week to week | Free plan | Yes |
5 of 5 tools
The ranking
In order, with what each tool is for and what it costs. Use the filters above to narrow the list.
Best for SEO teams and agencies that research competitors' backlinks and keywords
Ahrefs is an SEO platform for marketers and agencies that research backlinks, keywords and competitors on any website. Starter and Lite charge a credit for each report opened or filter applied, while Standard and higher give every user unlimited credits.
Free plan
paid from $29/mo
Best for technical SEOs who audit large or JavaScript-heavy sites from their own computer
Screaming Frog SEO Spider is a desktop crawler for Windows, macOS and Linux that audits websites for technical SEO issues. The free version stops at 500 URLs per crawl, and a paid license costs $279 per user a year.
Free plan
paid from $23.25/mo
Best for content teams that brief writers and check each article against the search results
Surfer is a content optimization platform for teams that publish articles regularly, scoring drafts against top-ranking pages as they're written. Plans are sized by documents, where each Content Editor counts as one, and Keyword Research starts on Standard.
$49/mo
7-day free trial
Best for marketing teams that want daily rank tracking and competitor research in one login
Semrush is an online marketing platform for in-house teams and agencies, combining keyword, competitor and backlink research with daily rank tracking and site audits. Each plan includes one user, and extra users cost $45 to $100 a month.
Free plan
paid from $117.33/mo
Best for in-house marketers tracking a few sites' rankings and crawl issues week to week
Moz Pro is an SEO suite for in-house marketers and small agencies, with keyword research, link data, weekly rank tracking and site crawls. Each Campaign tracks one site and three competitors, and Moz doesn't say what yearly plans cost after year one.
Free plan
paid from $49/mo
Head to head
Feature-by-feature matchups between leading SEO Tools tools, with a clear verdict.
Methodology
We compare the tools on this page using what can be checked from the outside: published pricing and plan limits, documented features, and each vendor's own security, compliance and support documentation. This is desk research, not hands-on testing. Where something can only be judged by using a product, we say so rather than imply we measured it.
What we weigh here:
How the order is set:
Buyer's guide
Search volume isn't a count of real searches. Surfer, for example, reports 12-month averages from data partners, and Ahrefs adds third-party keyword data to its own crawls. Use the numbers to decide which keyword is bigger than which, not to forecast traffic.
Headline prices cover one user. An extra seat costs $45 to $100 a month on Semrush, $40 to $80 on Ahrefs' Lite, Standard and Advanced plans and $49 on Moz Pro, and each Screaming Frog license covers one person. Count everyone who needs a login and price that, because a $139-a-month plan for four people means three extra seats.
Ahrefs is built around Site Explorer, which shows any domain's backlinks and organic and paid keywords. Semrush tracks rankings daily and sells local, content and advertising toolkits on top. Moz Pro bundles weekly rankings, crawls and on-page grades for a site and three competitors. Screaming Frog crawls sites from your own computer for $279 per user a year, and Surfer scores drafts against top-ranking pages as they're written.
Nearly every plan meters something: a credit for each report or filter on Ahrefs Starter and Lite, 150 Keyword Explorer queries a month on Moz Pro Standard, documents on Surfer, and one set of limits shared by every user on a Semrush account. Estimate a busy month rather than an average one, then buy the tier that covers it.
FAQ
On monthly billing, Moz Pro Standard costs $99 a month, Surfer Standard $119, Ahrefs Lite $129, Semrush's SEO plan $139 and Ahrefs Standard $249. Paying yearly brings Semrush's SEO plan to $117.33 a month, Surfer Standard to $99 and Moz Pro Standard to $79 a month for the first year. Screaming Frog's SEO Spider costs $279 per user a year. Extra seats add $40 to $100 a month on the suites, so price your whole team, not one login.
Choose Semrush if you report rankings daily, and Ahrefs if link and competitor research is the core of the work. Semrush's Position Tracking updates daily, and its SEO plan costs $139 a month, or $117.33 a month billed yearly. Ahrefs updates rankings weekly, but Site Explorer shows any domain's backlinks and organic and paid keywords, and API access starts on Lite at $129 a month. See Ahrefs vs Semrush.
They're estimates, not counts of real searches. Surfer, for example, reports 12-month averages from its data partners, and Ahrefs adds third-party keyword data to its own crawls. Use the figures to compare keywords with each other, not to forecast traffic.
Often, because the tools split the work. Ahrefs, Semrush and Moz Pro each cover keyword research, backlinks, rank tracking and site audits, so one of them usually handles research. Screaming Frog adds a desktop crawler with JavaScript rendering and custom extraction for $279 per user a year, and Surfer adds draft scoring for writers. Two suites mostly duplicate each other, and Ahrefs and Semrush both include paid search data.
Domain Authority is a 1-to-100 score Moz built to predict how likely a site is to rank compared with its competitors, mainly from backlink data. Moz says it isn't a Google ranking factor and has no effect on search results, and calls it a relative metric. Use it to compare sites, for example when prioritizing link building, not as a goal. Moz notes that raising a score from 20 to 30 is easier than from 70 to 80.
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