Raycast Favicons Service

A service used in the Raycast app to fetch and serve favicons from websites.

Setup

Create a .env file:

NODE_ENV=development
RAYCAST_IGNORE_CACHE=false # set to true to always look for favicons rather than using cache
REDIS_URL=redis://localhost:6379
AWS_ACCESS_KEY_ID=... # for S3
AWS_SECRET_ACCESS_KEY=... # for S3

Usage

Development:

bun dev # served at :3000. use `PORT=NNNN bun dev` to specify port

Load favicon:

curl http://localhost:3000/favicon?url={encoded URL}

Parameters:

• url: encoded URL (e.g. encoded with encodeURIComponent())
• size: supports favicon, 32 or 64
• dpr: pass the scale factor along with required size in points to get icons that look good at e.g. @2x or @3x

Implementation

• Uses RxJS to implement the concurrent behaviour of finding the best favicon from a given URL
• Looks for favicons from:
  • /favicon.ico (and /favicon.ico at any recursive subdomains)
  • <link /> tags found from loading the page at the given URL
  • The website's web application manifest (if it exists)
• Protection from abuse:
  • Utilises timeouts when loading all resources
  • Has data length limits for both images and other resources to prevent resource exhaustion attacks