The Complete On-Page SEO Checklist (45 Checks, Free Tools Included)

On-page SEO is the part of ranking you actually control. You can’t make other sites link to you on demand, but you can make sure every page tells search engines exactly what it’s about and gives them no reason to bury it. This is the checklist we run on every page — 45 checks across nine areas — with a free, no-signup tool for each one.

Want it done in one pass instead of by hand? Paste a URL into the SEO Analyzer and it runs all of these at once, scores them 0–100, and hands you a prioritized fix list. The rest of this guide explains why each check matters so the score means something.

1. Meta tags

Your title tag is still one of the strongest on-page signals and the single biggest lever on click-through from search results.

• Title: unique per page, 50–60 characters, primary keyword near the front. Longer than ~580px and Google rewrites it for you — usually into something worse.
• Meta description: not a ranking factor, but it’s the ad copy for your search result. One clear sentence, under ~155 characters.
• Canonical: every page should declare a self-referencing canonical unless it’s intentionally a duplicate.
• Robots meta: make sure you’re not accidentally shipping noindex on a page you want ranked — it’s the most common “why isn’t this in Google” cause.

Check any page’s tags with the Meta Tag Analyzer, or generate fresh ones with the Meta Tag Generator.

2. Heading structure

Headings are how both readers and crawlers parse a page’s outline.

• Exactly one <h1> per page, closely matching the title.
• Don’t skip levels (<h2> → <h4>). A clean hierarchy is an accessibility win as much as an SEO one.
• Work your primary topic into the H1 and at least one H2 naturally — not stuffed.

Audit the full heading tree of any URL with the Heading Structure Checker.

3. Content signals

Thin pages rank poorly. There’s no magic word count, but a page with 150 words of body text rarely competes with one that genuinely answers the query.

• Cover the topic completely enough that a reader doesn’t need a second tab.
• Avoid keyword stuffing — modern ranking is about topical coverage, not hitting a density percentage.
• Keep content fresh; a “last updated” date and real revisions matter for competitive queries.

Sanity-check your term distribution with the Keyword Density Analyzer — use it to catch over-optimization, not to chase a number.

4. Links

• Internal links: every important page should be reachable in a few clicks and linked from related content with descriptive anchor text (“click here” tells Google nothing).
• External links: linking out to authoritative sources is fine and often helpful.
• Broken links and redirect chains: every dead link wastes crawl budget and every extra redirect hop leaks a little link equity.

Map a page’s internal and external links with the Link Analyzer, and trace any redirect path with the Redirect Checker.

5. Image SEO

• Every non-decorative image needs descriptive alt text — it’s the only way crawlers understand the image, and it’s an accessibility requirement.
• Set explicit width and height (or aspect-ratio) so images don’t cause layout shift.
• Use modern formats (WebP/AVIF) and lazy-load below-the-fold images.

The Image SEO Checker lists every image on a page with pass/fail status for alt text and dimensions.

6. Open Graph & social tags

When someone shares your page, og: tags decide whether it looks like a polished card or a bare URL.

• og:title, og:description, and a 1200×630 og:image at minimum.
• twitter:card set to summary_large_image for a full-width preview.

Preview exactly how a page will look when shared with the OG / Social Card Preview.

7. Structured data (JSON-LD)

Structured data is how you become eligible for rich results — FAQs, breadcrumbs, articles, products — in Google Search.

• Use JSON-LD (Google’s preferred format), not microdata.
• Include every required field for the type, or the rich result silently won’t show.
• Keep the markup in sync with what’s visible on the page.

Validate what’s already on a page with the Structured Data Validator, and build new markup with the Schema Markup Generator.

8. Core Web Vitals

Core Web Vitals are a confirmed ranking signal and a real user-experience one. The three thresholds (measured at the 75th percentile of real users):

• LCP (Largest Contentful Paint) — load speed — should be ≤ 2.5s.
• INP (Interaction to Next Paint) — responsiveness, which replaced FID in 2024 — should be ≤ 200ms.
• CLS (Cumulative Layout Shift) — visual stability — should be ≤ 0.1.

We go deep on what causes each failure and how to fix it in Core Web Vitals Explained. The SEO Analyzer pulls your scores from the PageSpeed Insights API on demand.

9. Security headers & crawlability

The often-skipped technical layer that most free SEO tools ignore entirely:

• HTTPS everywhere, with Strict-Transport-Security (HSTS).
• A Content-Security-Policy and X-Frame-Options (or CSP frame-ancestors) to prevent clickjacking.
• A valid robots.txt that doesn’t accidentally block what you want crawled, and an XML sitemap referenced from it.

Grade a site’s headers with the HTTP Header Analyzer, and generate a clean robots.txt or sitemap.

The checklist, condensed

1. Unique title, 50–60 chars, keyword near the front
2. Meta description under ~155 chars
3. Self-referencing canonical
4. No accidental noindex
5. Exactly one H1, no skipped heading levels
6. Substantive, complete content (no thin pages)
7. Descriptive internal links; no broken links
8. Short redirect chains (ideally zero)
9. Alt text on every meaningful image
10. Explicit image dimensions (no layout shift)
11. Open Graph + Twitter Card tags with a real image
12. Valid JSON-LD with all required fields
13. LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1
14. HTTPS + HSTS + CSP + clickjacking protection
15. Valid robots.txt + sitemap

Work top to bottom, or skip the manual pass entirely: run the SEO Analyzer, fix what it flags as critical first, and re-run. Technical SEO won’t rank a thin page — but leaving these broken will keep a great page from ranking.