The Developer's SEO Checklist: 20 Things to Ship Before Launch

Why: The title tag is the strongest on-page ranking signal. Duplicate or missing titles waste it.

Fix: Set a unique title under 60 characters on every public page, with the primary keyword near the front.

// app/pricing/page.tsx
export const metadata: Metadata = {
  title: "Pricing", // renders as "Pricing | YourProduct" via template
}

Why: Descriptions appear in search results and influence click-through rate. Missing ones get auto-generated (usually badly).

Fix: Write a unique description under 160 characters for every public page. Write it like ad copy.

Why: Without canonicals, search engines may treat URL variants (with/without trailing slash, query params) as duplicate content.

Fix: Add alternates.canonical to every page's metadata export.

export const metadata: Metadata = {
  alternates: { canonical: "/pricing" },
}

Why: Without robots.txt, crawlers have no guidance. Some will index your dashboard or API routes.

Fix: Create app/robots.ts that allows / and disallows /dashboard/ and /api/.

// app/robots.ts
export default function robots(): MetadataRoute.Robots {
  return {
    rules: { userAgent: "*", allow: "/", disallow: ["/dashboard/", "/api/"] },
    sitemap: `${process.env.NEXT_PUBLIC_SITE_URL}/sitemap.xml`,
  }
}

Why: Sitemaps tell search engines which pages exist. Without one, discovery relies on crawling links, which is slower.

Fix: Create app/sitemap.ts. Submit the URL in Google Search Console.

// app/sitemap.ts
export default function sitemap(): MetadataRoute.Sitemap {
  return [
    { url: "https://yoursite.com", priority: 1.0 },
    { url: "https://yoursite.com/pricing", priority: 0.8 },
    { url: "https://yoursite.com/blog", priority: 0.7 },
  ]
}

Why: HTTP pages get a ranking penalty and browsers show security warnings. Mixed content (HTTP resources on HTTPS pages) triggers warnings too.

Fix: Serve everything over HTTPS. Search your HTML for http:// src or href attributes and replace them.

Why: Broken links waste crawl budget and frustrate users. Search engines penalize sites with many 404s.

Fix: Run a crawl or scan to find all internal links returning 404. Fix or remove them.

Why: The H1 is the strongest heading signal. Multiple H1s dilute it. No H1 wastes it entirely.

Fix: Ensure exactly one <h1> on every page with the target keyword inside it.

Why: Skipping levels (H1 then H4) confuses both search engines and screen readers.

Fix: Audit your headings. Use H2 for major sections, H3 for subsections. Never skip a level.

Why: Search engines cannot see images. Alt text is how they index visual content. It also powers accessibility.

Fix: Add alt text to every <img> and next/image. Describe what the image shows, not the filename.

Why: OG tags control how your pages look when shared on social media and in messaging apps. Missing ones show blank previews.

Fix: Add og:title, og:description, and og:image (1200x630px minimum) to every public page.

export const metadata: Metadata = {
  openGraph: {
    title: "Your Page Title",
    description: "One clear sentence.",
    images: [{ url: "/og-image.png", width: 1200, height: 630 }],
  },
}

Why: Structured data helps search engines understand your content type and can trigger rich results (FAQ snippets, product cards, etc).

Fix: Add SoftwareApplication schema to your landing page, BlogPosting to articles, FAQPage to FAQ sections.

Why: Clean URLs rank better and get more clicks. /blog/seo-checklist is better than /blog?id=42&ref=xyz.

Fix: Use lowercase, hyphenated slugs under 100 characters. Remove query params from canonical URLs.

Why: Client-side rendered pages may not be indexed by search engines. Googlebot handles JS, but not always completely.

Fix: Use SSG or SSR for every page you want indexed. Dashboard pages behind auth can stay client-rendered.

Why: Largest Contentful Paint is a Core Web Vital and a direct ranking factor. Slow LCP means lower rankings.

Fix: Add priority to above-fold images, use next/font, avoid layout shifts from web fonts loading late.

<Image
  src="/hero.png"
  alt="Product screenshot"
  width={1200}
  height={630}
  priority // preloads the image for faster LCP
/>

Why: Scripts in <head> without async or defer block rendering and hurt all Core Web Vitals.

Fix: Move scripts to the bottom of the body, or add async/defer. Use next/script with strategy='afterInteractive'.

Why: PNG and JPEG are 2-5x larger than WebP/AVIF at the same quality. Smaller images mean faster pages.

Fix: Use next/image (auto-converts to WebP). For static assets, convert manually with squoosh.app or sharp.

Why: Without the viewport tag, mobile browsers render pages at desktop width. Google's mobile-first index will penalize this.

Fix: Next.js adds this automatically. If you are using a custom layout, add it to your <head>.

<meta name="viewport" content="width=device-width, initial-scale=1" />

Why: AI search engines (ChatGPT, Perplexity) use llms.txt to understand your site without crawling every page.

Fix: Create a public/llms.txt with your product name, description, pricing, and key links.

Why: Many default robots.txt configs block all bots including AI search. Your content becomes invisible to ChatGPT and Perplexity.

Fix: Allow ChatGPT-User and PerplexityBot in robots.txt. Block training bots (GPTBot, CCBot) separately if desired.