Free SEO tools, sorted by the problem you have
Start from the thing that is actually worrying you rather than from a category. Every checker reads your live site with the same engine the full audit runs, and every generator runs in your browser.
A free SEO tool is useful for settling one observable fact about one live page. That is a genuinely narrow job and it covers most of what goes wrong: a directive nobody meant to ship, a canonical pointing at a redirect, a crawler quietly blocked, structured data that never parsed. What no free tool does is judge your business or crawl your whole site, and a list that implies otherwise is selling you something.
Which one do you need?
Find the sentence closest to your problem. Each one names the single check that settles it, and says what that check will and will not tell you before you run anything.
The two figures quoted above come from our own crawls, not from anybody's estimate: the crawler access number is from a sample of 1,048 sites, and the rendering one from 88 professional marketing sites that returned HTML to our fetcher. The two samples are not interchangeable. How often each check fails across all of them is in the technical SEO checklist, which is ordered by exactly that.
Checkers and generators are different jobs
Worth stating plainly, because for a long time we only did one of them. A checker reads a page you already have and reports what it found. A generator writes the artefact you do not have yet. Nineteen of the tools below are checkers, all running the same engine and leading with different parts of it. Three are generators, and those run entirely in your browser and send nothing anywhere.
robots.txt generator
Build the file from a form, with each AI crawler set separately in its own named group, and a resolved sitemap line.
Open generatorSchema markup generator
Valid JSON-LD for six types. Fields you leave blank are omitted rather than stubbed, so nothing describes what your page does not show.
Open generatorhreflang generator
Reciprocal tags for every locale in a set, as head tags or a sitemap, with the codes checked as you type.
Open generatorEvery checker, by what it reads
All nineteen run against a live URL and return a real result rather than an estimate. If you want all 36 checks in one report instead of one dimension at a time, that is what the full audit is.
Can AI assistants read and quote your site?
They read what an assistant actually gets: crawler access, the raw HTML before JavaScript runs, your structured data, and whether a passage can be lifted whole.
AI crawler checker
Check in one click whether GPTBot, ClaudeBot, PerplexityBot, Google-Extended and other AI bots are allowed to read your site.
Open toolllms.txt checker
llms.txt is the emerging manifest that points AI assistants at your most important, clean content. Check whether your site has one, and see the rest of your AI crawlability setup.
Open toolStructured data checker
AI and search engines use JSON-LD schema to understand who you are and cite you correctly. Check what structured data your page exposes and whether your Organization entity is defined.
Open toolJavaScript SEO checker
Most AI crawlers do not run JavaScript. If your content only appears after React or Vue hydrates, they see an almost empty page. This measures how much text is actually in your raw HTML.
Open toolAI content readiness
Assistants quote a passage, not a page. This measures whether yours can be lifted cleanly: sections a model can chunk on, answers in the first line, and someone named as the author.
Open toolContent freshness checker
Assistants and search engines weight recency, and an undated page reads as undated rather than as new. This checks whether your publish date, last modified date and a visible date are actually in the page.
Open toolIs your site being crawled and indexed?
They read the plumbing that decides whether a page is discovered, allowed into the index, and counted once rather than five times.
robots.txt checker
Fetch and parse your live robots.txt: whether it exists, whether it is valid, which crawlers it restricts and whether it points at your sitemap.
Open toolXML sitemap checker
Check whether your site serves an XML sitemap at the usual location, whether robots.txt points at it, and whether crawlers have a reliable list of your pages.
Open toolIndexability checker
The fastest way to find an accidental noindex. Checks the meta robots tag and the X-Robots-Tag header on your live page, plus what robots.txt allows.
Open toolCanonical tag checker
See whether your page declares a canonical URL, whether it points at itself, and where it points if it does not. The quiet cause of pages that will not rank.
Open toolhreflang checker
Check whether your page declares its language at all, and how many hreflang alternates it offers. The first thing to get right before any international rollout.
Open toolWhat does a search engine read on the page?
They read the tags and structure a search engine uses to work out what a page is about and how to display it.
Title tag checker
Read the actual title tag on your live page and its length, and see whether it will be truncated in search results. The single most important on page signal.
Open toolMeta description checker
See the meta description your page actually serves, its length, and whether it is missing entirely. The snippet decides the click after the ranking is already won.
Open toolH1 and heading checker
Count the H1s on your page, see the full heading outline, and find the level jumps and empty headings that break the structure a crawler reads.
Open toolOpen Graph checker
See what your page looks like when it is shared: og:title, og:description, og:image and the Twitter card tag, read from your live HTML.
Open toolImage alt text checker
Count how many images on your page are missing alt text, and see samples of the ones that are. Accessibility and image search read the same attribute.
Open toolHow fast and how hardened is the response?
They measure how fast the page answers, how heavy the document is, and what the response headers say about it.
Core Web Vitals checker
Real Lighthouse and field data from Google PageSpeed Insights for your live URL: performance score, LCP, INP and CLS, with your server response time measured separately.
Open toolPage speed checker
Measure what actually slows the page down: server response time, the size of the HTML document itself, and the scripts and stylesheets blocking the first paint.
Open toolSecurity headers checker
Check the five response headers that harden a site in the browser, plus any mixed content loading over plain http from an https page.
Open toolWhat a free tool cannot tell you
Anything that needs more than one URL. Duplicate titles across a template, a canonical pattern applied to two hundred pages, a redirect chain, whether an hreflang set is reciprocal. Those are properties of a site rather than of a page, and a single URL check cannot see any of them by construction. Each tool page says where its own check stops, which is the section worth reading before you trust a green result.
Whether anything is true. We can tell you that your structured data parses and declares a Product with a price. We cannot tell you the page shows that price, and that is the version with a policy attached. Same for alt text: a tool can confirm the attribute exists and not that it describes the image.
What any ranking system is doing. Googlepublished guidance in June 2026saying that no third-party tool has access to its internal ranking or AI systems. That applies to every score in this category including ours. These are models of what is observable from outside, which is useful for finding what is broken and is not a reading from inside anybody's index.
Questions people ask about free SEO tools
What are the best free SEO tools?
The honest answer is that it depends entirely on which question you have. Free tools are strong at settling a specific technical fact about a live page: whether it is indexable, what its canonical points at, whether its structured data parses, whether a crawler is allowed in. They are weak at anything requiring a crawl of a whole site or a judgement about your business.
Are free SEO tools accurate?
For observable facts about a page, yes, and you can verify most of them yourself with a browser and a terminal. For scores and difficulty ratings, treat every one of them, ours included, as a model of the outside of a system. Google published guidance in June 2026 stating plainly that no third-party tool has access to its internal ranking or AI systems.
How many free tools do you run?
Twenty two: nineteen checkers that read a live URL and three generators that build a file for you. The checkers all run on the same audit engine and lead with different parts of it, which is worth knowing before you run several expecting different opinions. The full audit runs all 36 checks at once.
Do I need an account?
Not for the generators, which run entirely in your browser and send nothing anywhere. The checkers fetch your live site, so a free account exists to keep the report attached to somebody and to stop the endpoint being used as an open crawler. There is no card and no trial.
What can a free tool not tell me?
Anything that needs more than one URL. Duplicate titles across a template, a canonical pattern applied to two hundred pages, a redirect chain, whether your hreflang set is reciprocal: all of those are properties of a site rather than of a page, and a single URL check cannot see any of them by construction.
Which check should I run first?
Whichever matches the symptom you actually have, which is what the table near the top of this page is for. If you have no specific symptom, start with crawler access and indexability, because they are close to binary and nothing else you fix matters while either is failing.
Related reading: the technical SEO checklist, ordered by what actually fails, what a canonical tag is and when it is ignored, which redirect to use and when, robots.txt examples from real websites, the SEO report template, in Word, Excel and CSV, how to run a content audit, keyword rank tracking with the SERP context, SEO tips ranked by how often the thing is broken, schema markup examples that validate, and why your Core Web Vitals score keeps moving.