Sepolia balance

main.go

package main

import (
	"context"
	"crypto/ecdsa"
	"fmt"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethclient"
	"os"
)

var ctx = context.Background()

func main() {
	privKey := getKey()

	pubKey := privKey.Public()

	addr := crypto.PubkeyToAddress(*pubKey.(*ecdsa.PublicKey))
	fmt.Printf("Your address is %v\n", addr)

	client, err := ethclient.Dial("https://rpc.sepolia.org/")
	check(err)

	b, err := client.PendingBalanceAt(ctx, addr)
	check(err)

	fmt.Printf("Balance is %v wei (wei is 10^-18 ETH)\n", b)
}

func getKey() *ecdsa.PrivateKey {
	const filename = "./private_key"

	privKey, err := crypto.LoadECDSA(filename)
	if err != nil {
		if os.IsNotExist(err) {
			privKey, err = crypto.GenerateKey()
			check(err)

			err = crypto.SaveECDSA(filename, privKey)
			check(err)
		} else {
			panic(err)
		}
	}

	return privKey
}

func check(err error) {
	if err != nil {
		panic(err)
	}
}