SEO Checker: Fix What It Finds

An SEO checker scans a page or a whole site and hands you a list of problems: missing titles, slow loads, broken links, thin content, and more. The scan is the easy part. This guide explains what a good checker actually inspects, which free tools do the job well, and how to fix each category of issue it flags without guessing.

What an SEO checker inspects

Behind the single "Check my SEO" button sits a crawler that requests your pages the way a search engine would, then compares what it finds against a checklist of known ranking and usability factors. The checks fall into three groups. On-page checks look at each page's title tag, meta description, heading structure, content length, image alt text, and internal links. Technical checks look at status codes, redirects, canonical tags, robots directives, XML sitemaps, mobile friendliness, HTTPS, and page speed. Off-page checks estimate authority, mostly through backlinks, which free tools can only partly see.

None of this is secret. Google's SEO starter guide lays out the same fundamentals a checker measures against. The tool simply automates the comparison so you do not have to inspect every page by hand. For the strategy behind the checklist, see our complete guide to SEO.

The free tools that actually do the job

There is no need to pay for a first audit. These free tools, used together, cover almost everything a paid suite reports:

• Google Search Console. Free and authoritative because the data comes straight from Google. It shows which pages are indexed, which have errors, your Core Web Vitals status, mobile usability, and the queries you rank for.
• Google PageSpeed Insights. Free, no login. It measures Core Web Vitals for a single URL using both lab and real-world field data, then lists specific speed fixes.
• Screaming Frog SEO Spider. A desktop crawler whose free tier audits up to 500 URLs per crawl, which is enough for most small sites. It surfaces broken links, redirect chains, duplicate titles, and missing metadata in one pass.
• Ahrefs Webmaster Tools. Free after verifying your site. Its Site Audit checks for over 170 technical and SEO issues, and its Site Explorer shows a sample of your backlinks.
• Bing Webmaster Tools. Free, and its built-in SEO analyser flags on-page issues Google's tools do not phrase as plainly.

For a focused look at the audit workflow, our SEO audit guide and the Search Console walkthrough go step by step.

Fixing on-page issues

On-page problems are usually the quickest wins because you control the content directly. Work through the common flags:

• Missing or duplicate title tags. Every page needs one unique, descriptive title, ideally under about 60 characters so it does not truncate in results. Put the main phrase near the front.
• Missing meta descriptions. Write a unique 140 to 160 character summary per page. It is not a direct ranking factor, but a compelling one lifts click-through rate.
• Broken heading structure. Use one H1 per page and nest H2s and H3s logically. Do not skip levels for styling.
• Thin content. If a page has a few dozen words, either expand it to genuinely answer the query or merge it into a stronger page.
• Missing image alt text. Describe each meaningful image in plain language for accessibility and image search.

For the tag-level detail, our meta tags guide covers titles, descriptions, and robots meta in one place.

Fixing technical issues

Technical flags are where a checker earns its keep, because these problems are invisible when you browse your own site. The high-impact ones:

1. Broken links and 404s. A checker lists every internal link that returns a 404. Fix each by correcting the URL, restoring the page, or redirecting it to the best live equivalent. Our guide to broken links covers the full repair process.
2. Redirect chains. A link that hops through two or three redirects wastes crawl budget and slows users. Point the original link straight at the final destination and prefer a single 301 for permanent moves.
3. Canonical conflicts. When several URLs show the same content, a canonical tag tells Google which is the master. A checker flags pages that canonicalise to the wrong URL or to a redirect.
4. Robots and indexing blocks. A stray "noindex" tag or a robots.txt rule can hide pages you want ranked. Confirm every important page is actually indexable.
5. Missing or stale sitemap. Keep an accurate XML sitemap and submit it in Search Console so new pages are found quickly.

Core Web Vitals and page speed

Speed and stability are part of the ranking picture, and a checker will grade them. The three Core Web Vitals, as defined on web.dev, have clear targets: Largest Contentful Paint should happen within 2.5 seconds, Interaction to Next Paint should be 200 milliseconds or less, and Cumulative Layout Shift should stay at 0.1 or below, all measured at the 75th percentile of visits.

When PageSpeed Insights flags a poor score, the common fixes are: compress and correctly size images, serve modern formats like WebP, defer non-critical JavaScript, reserve space for images and ads so the layout does not jump, and enable caching. Our Core Web Vitals guide explains each metric and its fixes in depth.

Off-page signals a free checker can only glimpse

The third layer, authority, is largely about who links to you. Free tools show a sample of your backlink profile rather than the full picture, but that sample is enough to spot two things: whether you have any quality links at all, and whether you have obviously spammy ones. Google treats a link as a signal of trust, so a handful of relevant, reputable links outweighs hundreds of low-quality ones.

To review your links, use the free backlink views in Search Console and Ahrefs Webmaster Tools, then read our complete guide to backlinks to understand what you are looking at. Building those links is a content and outreach job, not something a checker can do for you.

Turning a report into an action plan

A raw export of 300 warnings is paralysing. Convert it into a short, prioritised plan:

1. Triage by severity. Group issues into "blocks indexing", "hurts users", and "cosmetic". Handle them in that order.
2. Batch similar fixes. If forty pages share a duplicate title pattern, fix the template once rather than page by page.
3. Log what you changed and when. SEO effects take days to weeks to appear, so a change log stops you second-guessing.
4. Re-scan after each batch. Confirm the issue is gone and that you did not introduce a new one.
5. Schedule a monthly recheck. Sites drift: new broken links, new slow pages. A short monthly audit keeps small problems small.

Pair this with strong keyword targeting from our keyword research tool guide, and the checker becomes a maintenance routine rather than a fire drill.

Frequently asked questions

Is there a genuinely free SEO checker?

Yes. Google Search Console and PageSpeed Insights are free from Google, Bing Webmaster Tools is free from Microsoft, Screaming Frog offers a free tier for up to 500 URLs, and Ahrefs Webmaster Tools runs a free Site Audit after you verify your site. Used together they cover nearly everything a paid suite reports.

How often should I run an SEO check?

Run a full audit when you launch or redesign, then a lighter check monthly. Sites accumulate broken links, slow pages, and indexing drift over time, so a short monthly pass catches problems while they are still small and cheap to fix.

What should I fix first when a checker finds dozens of issues?

Fix anything that blocks indexing first, such as accidental noindex tags or robots.txt blocks, then Core Web Vitals and broken links that hurt users, and only then cosmetic warnings. Prioritising by impact prevents you from spending hours on issues that barely move rankings.

Can a free SEO checker see all my backlinks?

No. Free tools show a sample of your backlink profile rather than the complete set, because full link indexes are expensive to maintain. The sample is still enough to judge overall link quality and to spot obviously spammy links, which is what matters for most site owners.

Do I need a perfect score to rank well?

No. Real sites rarely score 100 on every check, and they do not need to. A "good" Core Web Vitals grade and clean indexing matter far more than chasing a flawless number. Focus on issues that affect users and search engines, and treat minor warnings as optional polish.