Create a custom 404 error page

SkillWeb & browsing

Lets your agent review and validate the HTML markup of a custom 404 error page against front-end best practices.

Available today. Use it from your connected AI after setup.

Connect ahel once, and every AI you use reads what you have installed.

Then ask your AI: use the Create a custom 404 error page skill

About this capability

Use when reviewing templates, rendered HTML, or shared components related to Create a custom 404 error page. Validate the final browser-facing markup, not just the source framework abstraction.

What this skill tells your AI

The instructions your AI receives, as published by thedaviddias/front-end-checklist in skills/404-page/SKILL.md and read by ahel’s review.

A generic browser 404 page causes users to leave immediately—a well-designed custom page provides recovery paths and keeps users engaged with your site.

Quick Reference

  • Custom 404 pages retain users who encounter broken or moved links
  • Include search, navigation, and links to popular content
  • Maintain consistent branding and site design
  • Track 404 errors to identify and fix broken links
  • Return a real HTTP 404 so the page is not treated as a soft 404

Check

Verify that this website has a custom 404 error page with helpful navigation options. Confirm the route returns HTTP 404 and not a branded page with a 200 response.

Fix

Create a user-friendly 404 page with search functionality and links to important pages. Ensure the server or framework returns status code 404 so the page does not become a soft 404.

Explain

Explain how custom 404 pages help retain users who encounter broken links and why returning 200 for missing pages creates soft-404 indexing problems.

Code Review

Review templates, server-rendered HTML, and shared components that output markup related to Create a custom 404 error page. Flag exact elements, attributes, and routes where the rendered HTML violates the rule.


For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/en/rules/html/404-page

Signals

GitHub stars
74k
Forks
7k
Last commit
Aug 2026
Advanced
Catalog kind
skill
Gateway key
x-404-page
Source
github.com/thedaviddias/front-end-checklist