Audit and guidance for implementing functional, user-friendly 404 error pages.

Install

mkdir -p .claude/skills/404-page && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/16102" && unzip -o skill.zip -d .claude/skills/404-page && rm skill.zip

Installs to .claude/skills/404-page

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

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.
193 chars✓ has a “when” trigger
Beginner

Key capabilities

  • Verify custom 404 error pages
  • Confirm HTTP 404 status codes are returned
  • Check for helpful navigation options on 404 pages
  • Ensure consistent branding on 404 pages
  • Review templates and rendered HTML for 404 page markup

How it works

The skill verifies that a custom 404 error page exists, includes navigation options, maintains branding, and returns an HTTP 404 status code.

Inputs & outputs

You give it
rendered HTML or templates for a 404 page
You get back
validation of 404 page markup and HTTP status code

When to use 404-page

  • Validating 404 page markup
  • Improving site UX
  • Fixing soft 404 errors

About this skill

Create a custom 404 error page

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

When not to use it

  • When the task is not related to 404 error pages
  • When only the source framework abstraction needs validation

Limitations

  • The skill focuses only on 404 error pages.
  • It validates the final browser-facing markup, not just the source framework abstraction.

How it compares

This skill validates the final browser-facing markup and HTTP status of 404 pages, unlike manual checks that might miss status code issues.

Compared to similar skills

404-page side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
404-page (this skill)02moNo flagsBeginner
mobile-android-design1012moNo flagsIntermediate
elegant-design215moReviewIntermediate
tailwind-design-system342moNo flagsIntermediate

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