Favicon API

A free & self-hostable favicon API service built with TypeScript, Hono, and Bun. Fetch and serve website favicons with multiple format options, intelligent fallbacks, and proper HTTP caching.

Powered by Vemetric

Features

• Fast & Lightweight: Built on Bun runtime and Hono framework
• Smart Discovery: Automatically finds the best favicon from multiple sources
• Fallback API: Optional fallback to Google's favicon API when primary fetch fails due to bot protection (enabled by default)
• Format Support: PNG, JPG, ICO, WebP, SVG
• Image Processing: Resize and convert images on-the-fly
• Caching Ready: Sets proper HTTP cache headers for CDN/proxy integration
• Docker Ready: Easy deployment with Docker
• Fully Typed: Written in TypeScript with strict type checking

Quick Start

Local Development

# Install dependencies
bun install

# Start development server (with hot reload)
bun run dev

# The server will start on http://localhost:3000

Using Docker

Option 1: Use Pre-built Image from Docker Hub

# Run with default settings
docker run -d \
  -p 3000:3000 \
  --name favicon-api \
  --restart unless-stopped \
  vemetric/favicon-api

# Or run with custom configuration
docker run -d \
  -p 3000:3000 \
  --name favicon-api \
  --restart unless-stopped \
  -e PORT=3000 \
  -e DEFAULT_IMAGE_URL=https://example.com/default-favicon.png \
  -e USE_FALLBACK_API=true \
  -e CACHE_CONTROL_SUCCESS=604800 \
  -e CACHE_CONTROL_FALLBACK=604800 \
  -e CACHE_CONTROL_ERROR=604800 \
  -e REQUEST_TIMEOUT=5000 \
  -e MAX_IMAGE_SIZE=5242880 \
  -e ALLOWED_ORIGINS=* \
  -e BLOCK_PRIVATE_IPS=true \
  vemetric/favicon-api

# Check it's running
curl http://localhost:3000/health

Option 2: Build from Source

# Build the image
docker build -t favicon-api .

# Run the locally built image
docker run -d \
  -p 3000:3000 \
  --name favicon-api \
  --restart unless-stopped \
  favicon-api

API Usage

Single Endpoint

GET /<domain>&response=<json|image>&size=<number>&format=<png|jpg|webp>&default=<url>

Query Parameters

• size (optional): Desired image size in pixels (16-512)
• format (optional): Image Output format - png, jpg, webp
• response (optional): Response format - image (default) or json
• default (optional): Fallback image URL (overrides server config)

Examples

Get favicon as image:

curl "http://localhost:3000/github.com"

Get favicon metadata as JSON:

curl "http://localhost:3000/github.com&response=json"

Resize favicon to 64x64:

curl "http://localhost:3000/github.com&size=64"

Convert to PNG:

curl "http://localhost:3000/github.com&format=png&size=128"

With custom fallback:

curl "http://localhost:3000/example.com&default=https://mysite.com/fallback.png"

Configuration

Create a .env file (see .env.example):

• DEFAULT_IMAGE_URL unset: use the bundled default.svg fallback image
• DEFAULT_IMAGE_URL=https://example.com/default-favicon.png: use a custom fallback image
• DEFAULT_IMAGE_URL=none: disable the default fallback image and return 404 when no favicon is found
• CACHE_CONTROL_FALLBACK: cache time for fallback responses after favicon lookup fails, including default images and disabled-fallback 404 responses

Architecture

The application is a stateless processor with no built-in caching. It:

1. Processes requests and finds favicons
2. Sets proper HTTP cache headers
3. Returns images or JSON responses

For production, add a caching layer in front (CDN or reverse proxy):

• Cloudflare (free tier)
• BunnyCDN, KeyCDN (paid)
• Nginx/Caddy (self-hosted)

Development

# Install dependencies
bun install

# Run development server (with hot reload)
bun run dev

# Run tests
bun test

# Run tests in watch mode
bun test --watch

# Type check
bun run typecheck

# Lint
bun run lint

# Format code
bun run format

Deployment

Option 1: Docker (Recommended)

Using Pre-built Image:

# Pull and run from Docker Hub
docker run -d \
  -p 3000:3000 \
  --name favicon-api \
  --restart unless-stopped \
  vemetric/favicon-api

# Verify it's running
curl http://your-server-ip:3000/health

Building from Source:

git clone https://github.com/vemetric/favicon-api.git
cd favicon-api

# Build and run
docker build -t favicon-api .
docker run -d \
  -p 3000:3000 \
  --name favicon-api \
  --restart unless-stopped \
  favicon-api

# Verify it's running
curl http://your-server-ip:3000/health

Option 2: Direct with Bun (No Docker)

# Install Bun
curl -fsSL https://bun.sh/install | bash

# Clone and run
git clone your-repo
cd favicon-api
bun install
bun run start

With CDN (Recommended for Production)

Cloudflare Setup:

1. Add domain to Cloudflare
2. Point A record to your server IP
3. Enable "Proxy" mode (orange cloud)
4. Configure cache rules to respect origin headers

BunnyCDN Setup:

1. Create pull zone pointing to your origin
2. Enable "Respect Cache Headers"
3. Point CNAME to CDN hostname

Favicon Sources

The API searches multiple sources for favicons:

1. <link rel="icon"> tags
2. <link rel="apple-touch-icon"> tags
3. Web manifest files (manifest.json)
4. Common fallback locations (/favicon.ico, /apple-touch-icon.png)
5. Google's favicon API (optional fallback when primary sources fail due to bot protection or other issues)

Favicons are ranked by quality (size, format, source) and the best one is returned.

Fallback Strategy

When the primary favicon fetch fails (e.g., due to bot protection), the API can optionally fall back to Google's favicon service:

1. Primary fetch: Attempts to fetch favicon from the website's own sources
2. Fallback API (if enabled via USE_FALLBACK_API=true): Queries Google's favicon API
3. Default image: Returns the configured default fallback image, the bundled default.svg if no custom default is configured, or 404 when DEFAULT_IMAGE_URL=none

The Google API fallback is enabled by default and provides reliable results even for sites with strict bot protection. To disable it, set USE_FALLBACK_API=false in your environment configuration.

Used by

The following projects are using the Favicon API:

• Vemetric - Simple, yet actionable Web & Product Analytics
• Orshot - Scale your Marketing with Automated Visuals
• OpenPanel - Next Generation Web Hosting Panel
• MCP Use Inspector Modern MCP Inspector with Apps SDK Support

Are you using the Favicon API and wanna be listed here? Feel free to file a Pull Request!

Credits

This project was mainly coded using Claude Code. We're also using the following libraries:

• Bun - Fast JavaScript runtime
• Hono - Lightweight web framework
• Sharp - Image processing
• Cheerio - HTML parsing