An open source IP geolocation API that provides detailed information about IP addresses, including geographic location, ISP details, and network information. Compatible with ipinfo.io response format.

• 🌍 Geographic Location: City, region, country, postal code, timezone
• 🏢 ISP Information: Organization name with human-readable mappings
• 🔍 Hostname Resolution: Reverse DNS lookup with timeout
• 🚫 Bogon Detection: Identifies private, reserved, and special-use IP addresses
• 🔄 Auto-updating Databases: Hourly checks for MaxMind GeoLite2 database updates
• ⚡ Fast Response: Optimized for speed with concurrent operations

1. Clone and run:

   git clone https://github.com/tristandevs/ipinfo-api cd ipinfo-api go run main.go

2. Server starts on port 8080

curl http://localhost:8080/

curl http://localhost:8080/208.67.222.222

{ "ip": "208.67.222.222", "city": "San Francisco", "region": "California", "country": "US", "loc": "37.764200,-122.399300", "org": "AS36692 CISCO-UMBRELLA", "postal": "94107", "timezone": "America/Los_Angeles" }

{ "ip": "192.168.1.1", "bogon": true }

{ "status": 404, "error": { "title": "Wrong ip", "message": "Please provide a valid IP address" } }

The API automatically detects client IP from these headers:

• X-Forwarded-For
• X-Real-IP
• CF-Connecting-IP (Cloudflare)

The service automatically:

• Downloads GeoLite2 databases on first run
• Checks for updates every hour
• Uses atomic file replacement to prevent corruption
• Compares Last-Modified headers for efficient updates

Database sources:

• GeoLite2-ASN.mmdb
• GeoLite2-City.mmdb
• GeoLite2-Country.mmdb

• DNS lookup: 40ms context timeout, 50ms total timeout
• Database update checks: 10s
• Database downloads: 60s

The service includes human-readable mappings for major ISPs including:

• Cloud providers (AWS, Google Cloud, Microsoft Azure)
• CDNs (Cloudflare, Fastly)
• Major ISPs (Comcast, Verizon, AT&T, Charter)
• Hosting providers (DigitalOcean, Linode, Rackspace)

• Go 1.19+
• Internet connection for database updates
• ~100MB disk space for databases

Contributions welcome! Please feel free to submit issues and pull requests.