SEO Toolbox Online

Single-check SEO tools

62 free, single-purpose checks: enter a URL, get one answer with the fix. Every one of them also runs inside the full SEO audit; use these for a quick spot-check of one thing.

On-Page SEO Checkers

Article Publish Date

Finds the published date in Article schema, meta tags or a <time> element.

Canonical Tag Checker

Checks for a canonical tag and that it resolves to an absolute URL.

H1 Checker

Checks the page has an H1 heading and flags pages that use more than one.

Header Tag Checker

Checks the H1–H6 hierarchy is sequential and no heading is empty.

HTML Lang Attribute Checker

Checks <html> declares a valid lang attribute.

Image Alt Tag Checker

Scans every image on the page for a missing alt attribute.

Keyword Density & Consistency Tool

Shows how your top keywords are distributed across title, meta and headings.

Meta Description Checker

Checks a meta description is present and within the recommended length.

SERP Preview Tool

Shows how the page may appear in search results.

Title Tag Checker

Checks the title tag exists and is within the recommended length.

Website Word Count Tool

Counts the visible words on a page and flags pages with very little text.

Structured Data & Social Tag Checkers

Hreflang Checker

Validates hreflang annotations and checks for a self-referencing entry.

Identity Schema Checker

Looks for Organization or Person markup naming who is behind the site.

Local Business Schema Checker

Checks for LocalBusiness structured data on pages that look local.

Open Graph Tags Checker

Checks Open Graph tags are present and og:image is an absolute URL.

Schema.org Checker

Detects Schema.org structured data and validates every JSON-LD block.

Social Media Links Checker

Looks for links to your Facebook, X, Instagram, LinkedIn and YouTube profiles.

X (Twitter) Cards Checker

Checks for X Card tags that control how the page looks when shared on X.

Indexing & AI Crawler Checkers

AI Crawler Blocked Checker

Reads robots.txt and reports whether GPTBot, ClaudeBot, PerplexityBot and other AI crawlers are allowed in.

Crawlability Test

Checks status code, robots.txt, and noindex tag/header together — everything that decides whether a crawler can index the page.

llms.txt Checker

Checks whether the site publishes an llms.txt file at its root and, if it does, that it has a title and markdown links.

Googlebot Simulator

Strips the page to title, headings, readable text and links — what a basic crawler extracts.

Noindex Checker

Checks the meta robots tag and the X-Robots-Tag header for noindex, and says whether the page can be indexed.

Robots.txt Checker

Checks robots.txt exists, returns 200, and does not block this page.

URL Status Code & Redirect Checker

Reports the HTTP status code and the full redirect chain for the URL, however the redirects are configured.

XML Sitemap Checker

Checks for a valid XML sitemap, declared in robots.txt or at /sitemap.xml.

Page Weight & HTML Code Checkers

Deprecated HTML Tags Checker

Scans for obsolete HTML elements like <center>, <font> and <marquee>.

GZIP Compression Test

Checks the HTML response is served with gzip, brotli or deflate compression.

Image Optimization Checker

Checks images declare width/height and use lazy-loading below the fold.

Inline CSS Checker

Counts elements using a style="" attribute instead of a stylesheet.

Google AMP Tester

Reports whether the page is itself an AMP page or declares an amphtml alternate.

Webpage File Size Checker

Total download size of the rendered page, broken down by resource type.

Webpage JavaScript Error Checker

Loads the page in a real browser and reports any JavaScript errors thrown.

Mobile Usability & Accessibility Tests

Favicon Checker

Checks the page declares a favicon, the icon browsers and Google search results show.

Webpage iFrame Test

Detects embedded iframes and checks each has a descriptive title.

Meta Viewport Tag Checker

Checks the page specifies a viewport tag matching the device width.

Webpage Tap Target Size Tester

Checks links and buttons are large enough to tap accurately on a touchscreen.

Font Size and Legibility Checker

Checks rendered text is not too small to read comfortably on mobile.

Mobile Responsiveness Tester

Checks the viewport tag, tap targets, font size and horizontal scroll together.

SSL, HTTPS & Email Security Checkers

Clear-Text Email Checker

Scans the page for email addresses exposed in plain text.

DMARC Record Tool

Checks the domain publishes a valid DMARC record and reports its policy.

HTTPS (SSL) Redirect Checker

Checks the HTTP version of the URL redirects to HTTPS.

SPF Record Tool

Checks the domain publishes an SPF record listing who may send its email.

SSL Checker

Checks the TLS certificate is valid and reports its expiry.

Server, DNS & Technology Checkers

Facebook Pixel Checker

Detects a Facebook Pixel (and other tracking pixels) on the page.

Analytics Checker

Detects Google Analytics or another web-analytics tool on the page.

Built With Checker

Detects the CMS, frameworks, CDN and other technology a site is built with.

Character Encoding Checker

Reports the charset the page declares.

Website DNS Lookup

Resolves the A, AAAA and NS records for a domain to show where it points.

Website IP Address Finder

Finds the IPv4 and IPv6 addresses a domain resolves to.

Web Server Checker

Identifies the web server software and CDN powering a site.

HTTP/2 Usage Checker

Checks whether the origin negotiates HTTP/2 (or HTTP/3) via ALPN.

ads.txt Validator

Checks each line of ads.txt has the required domain, account id and relationship fields.

Ping Tester

Queries the site and reports whether it responded and how long it took.

Domain Age Checker

Looks up when the domain was registered via RDAP (the public WHOIS successor).

Link, Anchor Text & URL Checkers

Anchor Text Checker

Flags generic anchor text ("click here", "read more") on this page’s links.

Internal Link Checker

Counts internal vs external links on the page and their follow/nofollow mix.

SEO Friendly URL Checker

Checks the URL is readable — lowercase, hyphenated, no long parameter strings.

Core Web Vitals & Page Speed Tests

Core Web Vitals Test

Lab LCP and CLS, plus Total Blocking Time as a lab stand-in for INP, from a real Chromium render.

LCP Test

Lab Largest Contentful Paint against the Core Web Vitals thresholds.

CLS Test

Lab Cumulative Layout Shift against the Core Web Vitals thresholds.

Page Request Checker

Counts the network requests needed to load the page.