CSS

1. https://unsplash.com = 示例图片
2. https://uifaces.co = 示例用户面部图像
3. https://extract.pics/ = 从网站提取所有图像
4. https://color.adobe.com/ = 上传渐变图像并获取十六进制颜色代码
5. https://www.logo.wine/ = SVG 徽标
6. https://bennettfeely.com/clippy/ = 剪辑路径制作器
7. https://maketintsandshades.com/ = 色调和阴影生成器
8. https://coolors.co/contrast-checker/112a46-acc8e5 = 颜色对比度检查器

网络性能

1. https://pagespeed.web.dev/
2. https://www.webpagetest.org/
3. https://tools.pingdom.com/

执行JS：

1. https://runjs.app/play
2. https://jsbin.com/?html,输出
3. https://codepen.io
4. https://liveweave.com/
5. https://html-css-js.com/
6. https://jsfiddle.net/
7. https://onecompiler.com/html