Guide · website error checklist
Check Website for Errors: A Free Real-Browser Checklist (2026)
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To check website for errors, look for 404s and broken links, JavaScript console errors, failed requests, broken forms and sign-up, mobile overflow, missing analytics, slow pages and accessibility basics. A real browser on the live URL is reliable for visitor-visible behavior because it loads the deployed code, requests and layout that visitors receive; pair that evidence with manual checks where a browser run cannot verify the result.
Have a site ready to check? Test my site free. 10 browser runs a month after sign-up, without AI review. Add your URL and review a test plan before starting a run. See a sample report first.
First published · Facts checked
Free website error checklist
| Error type | How to spot by hand | Free tool | What Sybqa checks |
|---|---|---|---|
| 404s and broken links | Open important links and confirm the intended page appears instead of a 404 or error screen. | A link checker; DevTools Network for the returned status. | Page checks record HTTP errors and error screens on routes in the reviewed plan. It is not a whole-site crawler. |
| JavaScript console errors | Open DevTools Console, reload, and repeat the important journey. Separate errors from warnings. | Chrome or Firefox DevTools. | Records page and console errors encountered during the reviewed browser run. |
| Failed requests | In DevTools Network, reload and filter failed or 4xx/5xx requests. Inspect only non-sensitive request details. | Chrome or Firefox DevTools. | Records failed network requests encountered during the reviewed browser run. It does not prove backend correctness. |
| Broken forms and sign-up | Try empty, invalid and approved synthetic valid input; confirm clear errors and the expected visible result. | DevTools plus a fresh browser profile. | Runs form or sign-up steps and visible assertions that you approve in a journey. Email delivery, database writes and payment settlement need separate evidence. |
| Mobile overflow | Use a 320 px viewport and look for sideways scrolling, clipped text, overlap and covered controls. | DevTools device mode. | Checks reviewed pages at 1440 px, 390 px and 320 px, including overflow and overlap rules. |
| Missing analytics | Use the analytics provider’s live or debug view on the published domain and confirm consent behavior. | Provider debug view and DevTools Network. | Not checked. Sybqa does not verify analytics installation or event delivery. |
| Slow pages | Run the published URL, review lab results, then compare field data when available. | Lighthouse or PageSpeed Insights. | Does not produce Lighthouse, performance or Core Web Vitals scores. |
| Accessibility basics | Navigate by keyboard, inspect visible focus, labels and alternatives, then review automated findings. | Lighthouse and the W3C Nu HTML Checker. | Runs axe-core rules in the page and measures checks such as contrast during journey steps. Automated results do not establish accessibility conformance. |
| Invalid HTML | Validate key URLs, then review errors that can affect parsing, labels or layout. | W3C Nu HTML Checker. | Not checked as HTML conformance. Browser observations may expose resulting layout or journey failures. |
Start with the main visitor journey, then check the website launch checklist for the wider release inventory. For a smaller repeatable release pass, use the published-site smoke test.
Why check the live URL in a real browser?
Source code and builder previews do not show every deployment problem. The published site can have different environment settings, redirects, cached assets, API endpoints and responsive behavior. A fresh browser loads that deployed surface and lets you retain the route, viewport, steps and observed result.
Browser evidence has limits. A visible success message does not prove that an email arrived, an analytics event was stored, a payment settled or a database permission rule is safe. Keep those checks separate and use the system that owns each result.
For layout-specific steps, use the mobile-friendly testing guide. The sample website QA report shows how passed, failed, blocked and not-run results stay distinct.
Errors AI-built sites commonly ship
Sites built with Lovable, Bolt, v0 or Cursor can look complete in a preview while the published URL still breaks. These are practical checks, not claims that every builder or generated site has each problem.
- Preview-only configuration. A production API URL, environment value or auth redirect is missing or still points to the preview.
- Routes that work only through in-app clicks. Refreshing a nested published route returns a 404 because hosting rewrites are incomplete.
- Generated forms without a complete result. Validation appears, but valid submission fails, loops or shows success without evidence of the intended outcome.
- Desktop-first sections. Fixed widths, wide tables, sticky bars and dialogs overflow or cover controls at phone widths.
- Placeholder and error-state leaks. Template tokens,
undefined,NaN, loading states or raw request errors reach visible copy.
Use the AI-built website testing guide for a pre-launch sequence. Lovable users can also follow the published Lovable site guide for a fix-brief and retest workflow.
Common questions
How can I check my website for errors for free?
Open the published URL in a fresh browser, complete the main journey, inspect DevTools Console and Network, check links and forms, resize to 320 px, run Lighthouse or PageSpeed Insights, validate key pages with the W3C Nu HTML Checker, and test keyboard access. Record blocked and not-run checks separately.
What website errors should I check first?
Start with errors that stop the main visitor action: a page that does not load, a broken link, a failed request, a form or sign-up that cannot finish, or a control hidden by mobile overflow. Then review performance, analytics and accessibility basics with the appropriate tools.
Does Sybqa check every page on a website?
No. Sybqa checks routes and journeys in the plan you review. It records browser evidence for that scope, including encountered page, console and request errors, but it is not a whole-site crawler and does not turn blocked or not-run checks into passes.
Can a browser test prove analytics, email or payments work?
Not by itself. A browser can record the visible journey and requests, but analytics storage, email delivery, payment settlement and database changes need evidence from the systems that own those outcomes. Use test-mode services and synthetic data where consequential flows are approved.
Sources
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Try Sybqa on your site
Explore bugs, UI consistency and user journeys from a reviewed plan. Inspect browser evidence and visual review leads in the report. The free plan gives 10 runs a month without AI review after you sign up. See pricing.
Add your site link here and it will be waiting in the console after you create an account. Then describe one journey to check and review the test plan before any run starts.