The Developer's Pre-Launch Checklist: 40 Things to Check Before Shipping

You built the feature. Tests pass. Staging looks good. Time to ship, right? Not so fast. I've shipped enough broken things to know that there's a gap between "it works" and "it's ready." This is my checklist — the things I verify before every launch. Not everything applies to every project. Skip what's irrelevant. But scan the whole list at least once. Performance [ ] Page loads in under 3 seconds on a throttled connection (Chrome DevTools → Network → Slow 3G) [ ] Images are optimized — use WebP/AVIF, lazy-load below-the-fold images, serve responsive sizes [ ] No render-blocking resources — CSS and JS that block first paint are deferred or inlined [ ] Bundle size is reasonable — run npx bundlephobia or check your framework's build output [ ] API responses are fast — P95 latency under 500ms for critical endpoints [ ] Caching headers are set — static assets have Cache-Control: public, max-age=31536000, immutable with hashed filenames SEO & Social Sharing [ ] Every page has a unique &