A dialer which will reach clearnet, onion, and I2P sites, and an HTTP Client which has specific TLS behavior for Onion and I2P domains.
go get github.com/go-i2p/go-meta-dialer
package main
import (
    "fmt"
    "io/ioutil"
    "net/http"
    
    metadialer "github.com/go-i2p/go-meta-dialer"
)
func main() {
    // IMPORTANT: Close the dialers when done to prevent SAM/Tor session leaks
    defer metadialer.Garlic.Close()
    defer metadialer.Onion.Close()
    
    // Use the dialer directly
    conn, err := metadialer.Dial("tcp", "example.i2p:80")
    if err != nil {
        panic(err)
    }
    defer conn.Close()
    
    // Do something with the connection...
}
package main
import (
    "fmt"
    "io/ioutil"
    
    metadialer "github.com/go-i2p/go-meta-dialer"
)
func main() {
    // IMPORTANT: Close the dialers when done
    defer metadialer.Garlic.Close()
    defer metadialer.Onion.Close()
    
    // Create a new HTTP client
    client := metadialer.NewMetaHTTPClient(nil)
    
    // Make requests to any network
    resp, err := client.Get("https://example.com")           // Normal website
    // resp, err := client.Get("http://example.onion")       // Tor onion service
    // resp, err := client.Get("http://example.i2p")         // I2P site
    
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()
    
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        panic(err)
    }
    
    fmt.Println(string(body))
}
// Set the MetaHTTPClient as the default for all HTTP requests
client := metadialer.NewMetaHTTPClient(nil)
http.DefaultClient = client.HTTPClient()
metadialer.ANON = true: (Default) Routes all non-I2P connections through Tormetadialer.ANON = false: Only routes .onion domains through Tor, direct connection for regular domains