Free SEO tools that run in your browser
Preview snippets, test robots.txt rules, audit heading structure and measure readability — without uploading anything to a server.
Why “client-side” matters here
You are about to paste unpublished page copy, a staging robots.txt, or HTML from a site you are not ready to talk about. Every tool on this site processes that input as plain JavaScript on your own machine. Nothing is uploaded, nothing is logged, and there is no request attached to the text you type.
All tools
Meta Tag Generator
Emits title, description, canonical, Open Graph and Twitter tags with live length warnings.
SERP Preview Tool
Renders your title and description at Google's desktop width, measures them in pixels, and marks the exact truncation point.
robots.txt Tester
Test any URL against any user-agent and see the exact rule that wins, quoted with its line number.
Heading Structure Analyzer
Paste HTML and get a clean H1–H6 outline plus a list of real problems: missing or duplicated H1, skipped levels, and overly long headings.
Keyword Density Checker
Word and phrase frequency with 150+ English stopwords removed, calibrated on 44 real homepages — median top phrase 2.
Readability Score Checker
Flesch Reading Ease, grade level and the sentences dragging you down — calibrated on 46 real homepages (median 57), plus when to ignore the score.
llms.txt Generator
Build a valid llms.
JSON-LD Schema Markup Generator
Generate valid JSON-LD for Article, FAQ, HowTo, Product and Organization — or one @graph that links them by @id.
UTM Link Builder
Build campaign URLs with correctly encoded utm_source, utm_medium and utm_campaign.
Open Graph Preview Tool
Preview the card LinkedIn, Facebook, X and Slack render for your link, plus the checks that matter: missing og:image dimensions, empty tags.
hreflang Tag Generator
Generate hreflang as HTML link tags, an HTTP Link header or sitemap entries — validating bad language codes, missing return tags and x-default.
Guides
Meta Description Length: What Gets Truncated
The number everyone quotes is 155 characters. The real rule is pixel width, and knowing the difference saves you from rewriting descriptions that were fine.
robots.txt Mistakes That Silently Deindex Pages
Five configuration errors that remove pages from Google without producing any error message anywhere, plus the symptom map that tells you which one you have.
Heading Structure: What H1–H6 Order Actually Does
Headings are document structure, not a ranking lever. Here is what they genuinely affect, and what is folklore.
JSON-LD @graph: Why One Block Beats Five
Most sites emit one JSON-LD block per schema type and never connect them. A single @graph with @id references fixes the duplication.
A Pre-Publish SEO Checklist for Any New Page
Nine checks that take under ten minutes and catch the mistakes that are invisible after publishing. Ordered so that the cheap ones come first.
What 71 Sites Actually Put in robots.txt
We fetched the robots.txt of 78 high-traffic sites. A quarter declare no sitemap at all, and five still ship a directive Google ignores.
What 61 Homepages Actually Ship in JSON-LD
We parsed the JSON-LD on 61 homepages. Half ship none in their HTML, and 14 still carry markup for a feature Google retired in 2024.
What 62 Homepages Actually Ship in Open Graph
We read the Open Graph tags on 62 homepages. 90% have some, only 23% declare image dimensions, and two sites ship an og:image tag that carries nothing.
What 70 robots.txt Files Say About AI Crawlers
We read 70 robots.txt files and checked 22 AI crawler tokens in each. 63% never mention one, and the most famous crawler is blocked least often.
What 60 Sites Actually Do With hreflang
We parsed hreflang on 60 high-traffic homepages. Less than half declare it, and a third skip x-default — the tag Google recommends but never requires.
What 55 Homepages Actually Do With Canonical
We fetched the homepage of 78 well-known domains and read 55. Four in five declare a canonical; one in five ships a homepage with none at all.
llms.txt Adoption: 22 of 78 Big Sites
Half of 78 well-known sites return a clean 404 for /llms.txt. Of the 22 that serve one, 11 hide behind a redirect and 4 break their own heading.
What 59 Homepages Put in Their SERP Snippet
We fetched 78 well-known homepages and read 59. Every one ships a title; the median is 35 characters, and a fifth of the descriptions run long.
Whatsmyserp Alternatives: Pick by Job, Not Price
Two different jobs hide behind the phrase 'Whatsmyserp alternative', and most lists ignore the difference. Here is what each tool is actually for.
Why Google Won't Index Your Page: A Checklist
Indexing problems get diagnosed in the wrong order, so the fixes don't work. Here is the order that separates a code fault from a trust gate.
Sitemaps in the Wild: 55 of 78 Sites
We pulled 251 URLs out of 55 real sitemaps and requested each one: 1 in 8 answers with a redirect, and 25 of the 55 sitemaps were not at /sitemap.xml.
Redirect Chains in the Wild: 78 Domains
We walked http://bare-domain for 78 well-known sites: 37 take two hops to reach their own homepage, and 28 of those could have done it in one.
Heading Structure in the Wild: 53 Homepages
We parsed 1,696 headings from 53 well-known homepages: 16 have no single visible H1, and 22 open with something other than an H1.
Favicons in the Wild: 61 Homepages
We fetched every icon declared by 61 well-known homepages: 248 tags, 6 sites with nothing larger than 32x32, and a .ico that is really a WebP.
Indexing Directives in the Wild: 59 Homepages
We read the robots meta tags and response headers of 59 well-known homepages: 25 declare anything, 12 of those change nothing, and one noindexes itself.
Link rel in the Wild: 54 Homepages
We read all 10,121 links on 54 well-known homepages: 5 sites put nofollow on an outbound link, 1 uses sponsored, and nobody uses ugc.
Resource Hints in the Wild: 63 Homepages
811 resource hints on 63 homepages: preload and preconnect do the work, prerender is gone, and 81% of preconnects warm origins the HTML never mentions.
Images in the Wild: 55 Homepages
2,418 images on 55 homepages: 39.6% declare themselves decorative, 5.8% have no alt at all, and the first image is lazy-loaded on 13 sites.
HTML lang, Charset & Viewport: 60 Sites
60 homepages: one has no lang at all, three declare charset past the 1024-byte window, and four block zoom outright.
Security Headers in the Wild: 60 Sites
60 homepages: 92% send HSTS but 7 ask for less than a year and one asks for zero; 62% send a CSP and 73% of those allow inline script.
Forms and Labels in the Wild: 60 Sites
60 homepages, 146 form controls, but only 74 a screen reader actually reaches — and 2 of those have no name at all.
HTML Weight and Render-Blocking Scripts
60 homepages weigh 51 MB. The median is 414 KB, 60% still block the parser on a script, and one site ships a single 12.8 MB JSON file inside its HTML.
URL Normalization in the Wild
62 of 69 major sites serve a byte-identical duplicate of at least one common URL variant. We probed 78 sites with 13 requests each.