Unsplash

A thick-colored, wallpaper-suitable free material website. High-quality free image library covering themes like nature, architecture, and people.

Pexels

An extremely large collection of free HD materials, personal and commercial use both allowed. The images are exquisite and stylish, with weekly featured images on the site; the search bar has 'Trending Topics' showing recently popular image keywords, and you can also filter resources by color and image size; downloadable/uploadable images available along with dedicated apps.

Pic58

Designer commonly used material library, provides free and VIP-exclusive resources.

Gratisography

Free high-resolution images, freely usable for personal or commercial purposes, updated weekly; the website’s color scheme and logo are unique, with creatively themed and angled images; direct download available without login registration.

Alibaba Vector Icon Library

The largest domestic free vector icon library, suitable for UI designers.

Icons8

Massive free vector icon library, providing multiple styles (flat, skeuomorphic, etc.) and format downloads.

Font Awesome

World's most popular free vector icon library, providing SVG, web font, and multiple format support.

Material Icons

Google official Material Design style icons, free for commercial use.

Iconmonstr

Over 4500+ free high-detail black-and-white icons, supports SVG/PSD formats, free commercial use.

SF Symbols

Apple's official 3000+ vector icon library, perfectly compatible with iOS/macOS systems, requires Xcode download.

Undraw

Free open-source illustration library, all images can be used commercially, supports online main color modification.

TinyPNG

Smart PNG/JPG compression tool, significantly reduces file size while maintaining image quality.