On-page SEO is everything you control inside a single page's HTML. Get it right and search engines understand your page instantly; get it wrong and even great content struggles to rank. This is the checklist I run on every page — the same signals the SEO Inspector extension surfaces in one click.
Title & meta description
The <title> is still one of the strongest on-page signals and the headline users see in search results. Aim for roughly 50–60 characters (about 580px) so it isn't truncated — title tag optimization covers length, format and Google's rewrites in depth — put the primary keyword near the front, and make every title unique across the site.
The meta description doesn't directly affect ranking, but it's your ad copy in the SERP. Keep it around 140–160 characters, describe the page honestly, and include the terms people actually search for. If it's missing, Google will generate one from the page — usually worse than what you'd write.
Headings (H1–H6)
Use exactly one H1 per page that states what the page is about. Then structure the rest with H2s and H3s in a logical order — don't skip levels (H2 → H4) just for styling — the heading structure guide walks through getting H1–H6 right. A clean heading outline helps both readers scanning the page and crawlers building a content map.
If you can't understand a page from its headings alone, neither can a search engine.
Canonical & robots
The canonical tag tells search engines which URL is the "real" one when the same content is reachable at multiple addresses (trailing slashes, query params, http/https). Point it at the clean, preferred URL (full details in canonical tags and duplicate content) — usually self-referencing.
Check the robots meta tag and the X-Robots-Tag HTTP header: a stray noindex is the single most common reason a page silently disappears from Google. Make sure pages you want indexed say index, follow.
Images
Every meaningful image needs a descriptive alt attribute — it's an accessibility requirement and helps image search. Beyond that: serve modern formats (WebP/AVIF) — see the image SEO guide — size images to their display dimensions instead of shipping a 4000px photo into a 400px slot, and add loading="lazy" to below-the-fold images.
Links
Internal links spread authority and help crawlers discover pages — use descriptive anchor text, not "click here" (the internal linking guide covers structure, anchors and orphan pages). Audit for broken links (404s) and unnecessary redirect chains (each hop wastes crawl budget and slows users). Add rel="nofollow" or sponsored where appropriate on paid or untrusted outbound links.
Structured data
JSON-LD structured data (Schema.org) unlocks rich results — star ratings, FAQs, breadcrumbs, product info. Add the type that matches your content (Article, Product, FAQPage…) and validate it so all required fields are present. Even a basic WebSite + Organization markup helps.
Performance
Core Web Vitals are a ranking factor. Watch LCP (loading), CLS (visual stability) and INP (responsiveness). The usual wins: compress and lazy-load images, defer non-critical JavaScript, reserve space for images/ads to avoid layout shift, and cache aggressively.
Putting it together
You don't need to memorise all of this — you need a repeatable pass. Open a page, check the title and description lengths, confirm a single H1 and a sane heading outline, verify canonical/robots, scan images for missing alt, look for broken links, and glance at Web Vitals. That's a 60-second audit that catches 90% of on-page problems.
If you'd rather not do it by hand, SEO Inspector runs this exact checklist in your browser and flags anything missing with colour-coded warnings — free, and nothing leaves your machine.
