This guide compares six website audit tools for small business owners. It is written for readers weighing a free Semrush alternative, an Ahrefs alternative, or pricing before committing to a paid platform. A website audit tool is software that scans a website and reports on issues affecting search rankings, performance, accessibility, and user trust. The six most widely used tools in 2026 are Google Lighthouse, Semrush, Ahrefs, Woorank, GTmetrix, and Stackra. Full disclosure: this comparison is written by the founder of Stackra, one of the six tools covered here. That means you should weigh the Stackra section with that in mind. What it also means is that I have spent considerable time studying what each of these tools actually does well and where they fall short. The goal is to give you an honest, structured breakdown of each tool: what it measures, who it is designed for, and where it has limits, so you can pick the one that fits your situation.

Six tools at a glance

The summary table below shows what each tool covers, who it is built for, and where it falls on the price scale. Detailed write-ups for each tool follow.

Comparison of the six most widely used website audit tools in 2026
ToolPriceBest forScopeOutput format
Google LighthouseFreeSingle-page technical baselineOne URL at a timeIssue list with category scores
SemrushFrom $117/moAgencies managing multiple sitesFull-site crawl + keywords + backlinksSeverity-grouped issues
AhrefsPaid (multi-tier)Backlink and competitor researchFull-site crawl + link indexErrors, warnings, notices
WoorankFrom $80/moNon-technical owners wanting a simple reportSingle-page summaryPlain-language report
GTmetrixFree + paidDiagnosing slow load timesSingle-page speed onlyWaterfall chart + tips
StackraFreeSmall business owners wanting business-focused recsUp to 20 pages, three pillarsScored report + prioritized action plan

Prices reflect the entry-level paid plan as listed on each vendor's site at time of writing. Free tiers and trials may exist at different limits.

Google Lighthouse

Lighthouse is a free, open-source tool built into Chrome DevTools and available as a command-line tool or via Google PageSpeed Insights. It measures performance, accessibility, SEO, and best practices for a single page. It is widely used because it is free, fast, built into Chrome, and closely aligned with how Google evaluates pages in its own tools. The main limitation is scope: it tests one URL at a time, does not track changes over time, and gives you a list of issues without telling you what to fix first.

Semrush

Semrush is an enterprise SEO platform with a site audit module. It crawls your entire site and flags technical issues: broken links, duplicate content, missing tags, redirect chains. It also covers keyword research, backlink analysis, and competitor tracking in the same subscription. It is the most popular choice among agencies managing multiple client sites. Paid plans start around $117 per month billed annually, or about $140 month-to-month. Issues are grouped by severity, but the total volume can be large and the interface takes time to learn for smaller teams.

Ahrefs

Ahrefs is best known for its backlink index, one of the largest in the industry. Its Site Audit tool crawls your pages and segments findings into errors, warnings, and notices. Where Ahrefs stands out is in competitive research: you can see exactly what keywords competitors rank for and which pages earn the most backlinks. Ahrefs Webmaster Tools is a free option for site owners who want basic audit access without a subscription. Paid plans are available at several tiers; the platform is priced for teams that need ongoing SEO and competitive data, not one-time assessments.

Woorank

Woorank is designed for non-technical users. Enter a URL and get a structured report covering SEO basics, mobile usability, security, and social signals. The interface is cleaner and simpler than Semrush or Ahrefs, which makes it a reasonable starting point for business owners who need a quick read without navigating a complex platform. It does not go as deep as dedicated SEO tools on technical crawl analysis or backlink data. Plans start around $80 per month.

GTmetrix

GTmetrix is a pure performance tool. It measures how fast your page loads, shows a waterfall chart of every resource request, and breaks down the largest contributors to slow load time. It is not a full-site SEO audit tool. Use GTmetrix when you already know your site is slow and need to diagnose exactly which files, scripts, or third-party requests are causing the problem. A free plan is available with limited test frequency; paid plans add more test locations and scheduled monitoring.

Stackra

Stackra crawls up to 20 pages and produces a scored report across three pillars: Conversion & Trust (marketing and trust), Search Visibility (SEO), and Technical Confidence (performance and security). Each pillar is reviewed by an AI persona for that specialty: a CMO, an SEO expert, and a CTO. The report includes a scored summary and a prioritized action plan. Stackra is free. It is aimed at small business owners and marketing teams rather than agencies managing large volumes of sites.

How to choose

Use Lighthouse when you want a free, fast technical baseline for a single page. Use GTmetrix when you need to diagnose slow load times specifically. Use Semrush or Ahrefs when you are managing SEO at scale across multiple sites or clients and need keyword and backlink data alongside technical audits. Use Woorank when you want a simpler interface without a steep learning curve. Use Stackra when you want a full-site assessment with business-focused recommendations and a clear starting point for improvement.

The best tool is the one whose output you will actually act on.

Frequently asked questions

Common questions about choosing and using website audit tools, with answers that apply across the six tools above.

What is a website audit tool?

A website audit tool is software that scans a website and reports on issues affecting search rankings, performance, accessibility, and user trust. Most tools fall into one of three groups: pure performance testers (Lighthouse, GTmetrix), enterprise SEO platforms (Semrush, Ahrefs), and SMB-focused scoring tools (Woorank, Stackra). Choose the category first based on what you need to learn, then pick the specific tool based on price and team size.

What is the best free website audit tool?

For a single-page technical baseline, Google Lighthouse and PageSpeed Insights are the most widely used free tools and are the closest to how Google itself evaluates pages. For a full-site audit with prioritized recommendations, Stackra is free and covers up to 20 pages. Ahrefs Webmaster Tools is also free for verified site owners and is best when you specifically want backlink data. The best free tool depends on whether you need depth on one page (Lighthouse), full-site coverage (Stackra), or backlink visibility (Ahrefs Webmaster Tools).

Is Lighthouse a website audit tool?

Yes. Lighthouse is Google's open-source auditing tool, available in Chrome DevTools, as a command-line tool, and through Google PageSpeed Insights. It tests a single URL across performance, accessibility, SEO, and best practices, and gives each category a score out of 100. Lighthouse is the technical baseline that most other audit tools either embed, reference, or compete with. It is free to use with no account required.

How is Stackra different from Semrush?

Semrush is an enterprise SEO platform built for agencies and in-house teams managing multiple client sites at scale. It bundles keyword research, backlink analysis, competitor tracking, and a full-site technical audit module into the same paid subscription. Stackra is a free, single-site audit aimed at small business owners and marketing teams who want a scored Growth Readiness report with a prioritized action plan, not a multi-tool platform. Semrush is broader and deeper for ongoing SEO work; Stackra is faster and more focused for one-time and quarterly assessments.

What is the best free Semrush alternative?

Honestly, no free tool replaces Semrush end to end. Semrush bundles a paid keyword database, a backlink index, rank tracking, and a full-site crawler in one platform. Free options cover individual slices, not the platform itself. By slice:

  • Keyword volume: Google Keyword Planner (free with a Google Ads account, returns ranges not exact figures)
  • Backlinks on your own site: Ahrefs Webmaster Tools (free for verified site owners)
  • Search position for your own pages: Google Search Console (free, shows queries you already rank for)
  • Technical audit: Google Lighthouse for a single page, or Stackra for a full site up to 20 pages (no keyword or backlink data)

What is the best free Ahrefs alternative?

Same honest answer: no free tool replaces Ahrefs end to end. Ahrefs is paid because it runs one of the largest backlink indexes in the industry, and that data has no free equivalent. Free options cover specific tasks:

  • Backlinks on your own site: Ahrefs Webmaster Tools (free for verified site owners only)
  • Search position for your own pages: Google Search Console (free)
  • Keyword volume estimates: Google Keyword Planner (free with a Google Ads account)
  • Technical audit: Google Lighthouse for a single page, or Stackra for a full site up to 20 pages (no backlink or competitive data)

How does Ahrefs pricing compare to free alternatives?

Ahrefs paid plans are tiered by user seats and project limits, built for teams running ongoing SEO and competitive research. Free options exist for slices, not the platform. Pricing in context:

  • Semrush: from $117 per month
  • Woorank: from $80 per month
  • Ahrefs: multi-tier paid plans, with Webmaster Tools as the only free option (verified site owners only)
  • Free combination: Google Search Console plus Lighthouse plus a free audit tool, scoped to your own site

How often should I run a website audit?

A full audit every quarter is a good baseline for most small business websites. Run an additional audit before and after any major change: a redesign, a platform migration, a new product or service launch, or a significant content update. If you are running active marketing campaigns, monthly checks on speed, broken links, and form functionality help catch problems before they cost you leads. Most tools listed above can be re-run on demand.

Do website audit tools fix issues automatically?

No. Every tool listed above only finds and reports issues. The fixes are still up to you, your developer, or your platform settings. The exceptions are issue-specific managed services (image-compression apps on Shopify, caching plugins on WordPress) that automate one narrow area, not the audit itself. When choosing a tool, weight the report quality and the prioritization of recommendations more heavily than the raw issue count, because the work to fix issues is what actually moves the score.