React Doctor
makeplane/plane
Scans React code for lint, accessibility, bundle size and architecture issues, reports a health score and checks that changes do not lower it.
A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web.
Install Image Optimization
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install thedaviddias/Front-End-Checklist image-optimization --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/image-optimization .claude/skills/image-optimization && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .claude/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimizationType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install thedaviddias/Front-End-Checklist image-optimization --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/image-optimization .agents/skills/image-optimization && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .agents/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install thedaviddias/Front-End-Checklist image-optimization --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/image-optimization .cursor/skills/image-optimization && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .cursor/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/thedaviddias/Front-End-Checklist.git --path skills/image-optimization--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install thedaviddias/Front-End-Checklist image-optimization --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/image-optimization .gemini/skills/image-optimization && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .gemini/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install thedaviddias/Front-End-Checklist image-optimizationInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/image-optimization .github/skills/image-optimization && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .github/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install thedaviddias/Front-End-Checklist image-optimization --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/image-optimization .opencode/skills/image-optimization && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "image-optimization" agent skill from https://github.com/thedaviddias/Front-End-Checklist/tree/main/skills/image-optimization into .opencode/skills/image-optimization/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "image-optimization", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
image-optimization- GitHub stars
- 74k
- Token cost
- ~715 tokens
- SKILL.md length
- 339 words
- Files
- 2 (incl. references)
- Skills in repo
- 390
- Repo updated
- First seen
- Licence
- MIT
At a glance
A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web.
- Reviewing image assets
- SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Build transforms related to Optimize all images for web
What it does
Image Optimization is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.
Its SKILL.md is about 720 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).
It sits in Frontend & Design, covering Web performance. The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.
When your agent uses it
- Reviewing image assets
- Build transforms related to Optimize all images for web
Example prompts
- “/image-optimization”
What it can do on your machine
Read from SKILL.md and the folder at commit e8d14d0. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
frontendchecklist.io
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Image Optimization loads about 715 tokens when it runs, and up to ~2.9k if it reads all its reference files. Until then it costs about 54 tokens; SKILL.md has 339 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 339 words, ~715 tokens.
Download SKILL.mdSave it as
.claude/skills/image-optimization/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.- name
- image-optimization
- description
- Use when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.
- metadata.category
- images
- metadata.priority
- high
- metadata.difficulty
- intermediate
- metadata.estimatedTime
- 20
- metadata.source
- frontendchecklist.io
- metadata.url
- https://frontendchecklist.io/rules/images/image-optimization
Optimize all images for web
Images typically account for 50%+ of page weight. Unoptimized images cause slow load times, wasted bandwidth, poor Core Web Vitals scores, and frustrated users—especially on mobile networks.
Quick Reference
- Use modern formats: AVIF > WebP > JPEG/PNG
- Compress images to 80% quality for photos
- Always provide responsive srcset for different screen sizes
- Use
<picture>element for format fallbacks
Check
Scan this codebase for all image assets and <img> elements. For each image, verify: 1) Format is appropriate (WebP/AVIF for photos, SVG for icons, PNG only for transparency). 2) Responsive srcset and sizes attributes exist for images > 100px wide. 3) width/height attributes are present to prevent layout shift. 4) loading='lazy' is set for below-fold images. 5) File sizes are reasonable (< 200KB for photos, < 50KB for graphics). Report issues grouped by severity with file paths.
Fix
For each image optimization issue found: 1) Convert JPEG/PNG photos to WebP with AVIF fallback using <picture> element. 2) Add srcset with 400w, 800w, 1200w, 1600w variants and appropriate sizes attribute. 3) Add explicit width/height attributes matching aspect ratio. 4) Add loading='lazy' to images below the fold, keep priority images without lazy loading. 5) Compress images to 80% quality for photos, 60% for AVIF. 6) Use SVG for icons and logos. Show the corrected HTML with optimized image markup.
Explain
Explain the impact of image optimization on Core Web Vitals, specifically how unoptimized images affect Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS). Cover the compression differences between AVIF, WebP, and JPEG formats, when to use each, and browser support considerations. Describe how srcset and sizes work together to serve appropriately-sized images, and why width/height attributes prevent layout shift. Include bandwidth savings calculations and loading performance improvements.
Code Review
Review image assets, markup, and delivery configuration related to Optimize all images for web. 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/rules/images/image-optimization
© thedaviddias, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 1 other file (references) in skills/image-optimization of thedaviddias/Front-End-Checklist.
- SKILL.md
- references/rule.md
Open the folder on GitHubat commit e8d14d0
Compare with similar skills
Image Optimization next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Image Optimization this skillthedaviddias/Front-End-Checklist | 74k | — | ~715 | Automated safety check: Pass | MIT | |
| React Doctormakeplane/plane | 60k | 12 repos | ~657 | Automated safety check: Pass | AGPL-3.0 | |
| Fixing Motion Performanceibelick/ui-skills | 9.4k | 5 repos | ~1.4k | Automated safety check: Pass | MIT | |
| GSAP Performance Tuninggreensock/gsap-skills | 16k | 4 repos | ~1k | Automated safety check: Pass | MIT | |
| React Frontend Development Guidelinesdiet103/claude-code-infrastructure-showcase | 10k | 2 repos | ~2.9k | Automated safety check: Pass | MIT | |
| Web Quality Auditaddyosmani/web-quality-skills | 2.9k | — | ~2.6k | Automated safety check: Pass | MIT |
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Google SEO APIs: Search Console (Search Analytics, URL Inspection, Sitemaps), PageSpeed Insights v5, CrUX field data with 25-week history, Indexing API v3, and GA4 organic traffic.
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Related
Categories
Questions about Image Optimization
What does Image Optimization do?
A skill your agent uses when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web. Image Optimization is an agent skill from thedaviddias/Front-End-Checklist. Use when reviewing image assets, markup, and CDN or build transforms related to Optimize all images for web.
When should I use Image Optimization?
Image Optimization fits situations like: reviewing image assets; build transforms related to Optimize all images for web.
How do I install Image Optimization in Claude Code?
Run `npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a claude-code`. Or copy the skill folder (skills/image-optimization in thedaviddias/Front-End-Checklist) into .claude/skills/image-optimization in your project. Claude Code loads it when a task matches its description.
How do I install Image Optimization in Codex?
Run `npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a codex`. Or copy the skill folder (skills/image-optimization in thedaviddias/Front-End-Checklist) into .agents/skills/image-optimization in your project. Codex loads it when a task matches its description.
Can I use Image Optimization in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add thedaviddias/Front-End-Checklist --skill image-optimization -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/image-optimization, .gemini/skills/image-optimization, .github/skills/image-optimization and .opencode/skills/image-optimization in your project.
What does Image Optimization need to run?
SKILL.md names no scripts, command-line tools or credentials: Image Optimization is instructions for the agent only.
Does Image Optimization access the network?
SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.
Is Image Optimization safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Image Optimization use?
Image Optimization is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Image Optimization use?
About 715 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2.2k tokens, read only when the agent opens those files.
What are the alternatives to Image Optimization?
Skills that share tags, products or a category with Image Optimization: React Doctor (makeplane/plane, 60k stars), Fixing Motion Performance (ibelick/ui-skills, 9.4k stars), GSAP Performance Tuning (greensock/gsap-skills, 16k stars) and React Frontend Development Guidelines (diet103/claude-code-infrastructure-showcase, 10k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Image Optimization?
thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,388 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.
Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.