Use WebP format with fallbacks

SkillMedia

webp-format is a skill for AI agents that reviews image assets, markup, and CDN or build transforms related to Use WebP format with fallbacks. It checks encoded size, rendered size, loading strategy, and above-the-fold impact together, so image format decisions are judged in context rather than in isolation.

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

Have an AI agent that can load skills.

Then ask your AI: use the Use WebP format with fallbacks skill

What your AI can do with it

  • Review image assets for WebP usage with proper fallbacks
  • Check markup and CDN or build transforms for image handling
  • Compare encoded size and rendered size of images
  • Evaluate loading strategy for images
  • Assess above-the-fold impact of image format choices

Getting started

  1. Have an AI agent that can load skills.
  2. Add the webp-format skill to the agent's available skills.
  3. Ask the agent to review the image assets, markup, or CDN and build transforms in question.
  4. Review the agent's findings on sizes, loading behavior, and above-the-fold impact.

What this skill tells your AI

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

WebP is smaller than JPEG and PNG at similar quality—using it reduces page weight by 25-35% for images, improving load times on all devices.

Quick Reference

  • WebP provides 25-35% better compression than JPEG/PNG
  • 97%+ browser support—nearly universal
  • Use picture element for older browser fallbacks
  • Supports transparency (like PNG) and animation (like GIF)

Check

Check if images are served in modern formats like WebP with fallbacks for older browsers.

Fix

Convert images to WebP format and implement proper fallback strategies.

Explain

Explain how WebP provides 25-35% better compression than JPEG and PNG.

Code Review

Review image assets, markup, and delivery configuration related to Use WebP format with fallbacks. Flag exact files or components where format choice, sizing, or loading behavior violates the rule, and describe how to confirm the fix in DevTools.


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

Rule page: https://frontendchecklist.io/en/rules/images/webp-format

Signals

GitHub stars
74k
Forks
7k
Last commit
Aug 2026

Questions

What does webp-format check?
It checks encoded size, rendered size, loading strategy, and above-the-fold impact together when reviewing whether images use WebP with proper fallbacks.
When should it be used?
Use it when reviewing image assets, markup, and CDN or build transforms related to WebP format with fallbacks.
Does it convert images to WebP?
The item describes review and checking of image assets and transforms; it does not state that the skill performs conversions itself.
Advanced
Item type
skill
Key
webp-format
Source
github.com/thedaviddias/front-end-checklist