Most developers treat SEO as "someone else's job" — a marketing concern that happens after the site ships. But a huge chunk of SEO is actually decided at the code level, long before a marketer ever touches the content. If you're building sites — for clients, for yourself, or as side projects — a few technical fundamentals can make or break how discoverable that work ever becomes.
Here's the technical SEO checklist I use when reviewing or building sites, from a digital marketing + web perspective. Core Web Vitals Aren't Optional Anymore
LCP (Largest Contentful Paint) — how fast the main content loads INP (Interaction to Next Paint) — how responsive the page feels to input CLS (Cumulative Layout Shift) — how visually stable the page is while loading
A site can have perfect content and still underperform in search if these numbers are bad. Common culprits: unoptimized images, render-blocking JS, and layout shifts from late-loading ads or fonts.
Lazy-load offscreen images Serve modern image formats (WebP/AVIF) Reserve space for dynamic content (ads, embeds) to avoid layout shift Defer non-critical JavaScript Structured Data Is a Developer Task, Not a Marketing One
Schema.org markup (JSON-LD is the recommended format) helps search engines — and increasingly AI-driven search summaries — understand what's actually on the page: is this a product, an article, a recipe, an FAQ?
Sites with well-implemented structured data are more likely to get rich results (star ratings, FAQ dropdowns, breadcrumbs) in search — which directly impacts click-through rate even without a ranking change.
If you're building a site and skip this step, you're leaving visibility on the table for something that's usually a few hours of implementation work. Rendering Strategy Affects Crawlability
Client-side rendered (CSR) React/Vue apps can still get indexed, but it's inconsistent and slower than server-rendered or statically generated pages. If SEO matters for the project:
Prefer SSR or SSG (Next.js, Nuxt, Astro, etc.) for public-facing, content-driven pages If CSR is unavoidable, make sure critical content isn't hidden behind JS that crawlers might not fully execute Test with actual crawler simulation tools, not just "it looks fine in the browser" Clean URL Structure and Internal Linking
This is often decided in routing/architecture decisions, not by marketers after the fact:
Descriptive, stable URLs (/blog/technical-seo-guide beats /post?id=8321) Logical hierarchy that mirrors site structure Internal links between related pages — this is one of the most underrated ranking factors, and it's basically free once the content exists Sitemaps and Robots.txt — Don't Ship Broken Defaults
A robots.txt accidentally blocking the whole site (extremely common on staging-to-production migrations) No XML sitemap, or one that's never updated Redirect chains left over from old URL structures
These take minutes to check and can be the difference between "indexed" and "invisible."
SEO isn't purely a content or marketing discipline — a meaningful part of it is architectural, decided in the codebase before any content strategy even starts. Developers who understand this end up building sites that are far easier for marketers (or themselves) to actually get found.
I work on the marketing/strategy side of this equation — SEO, performance marketing, and content — and write more at https://thenasim.com/. Always interested in the dev side of these conversations, so drop your take in the comments.