Example genesis file for a private Ethereum network

private.json

{
  "config": {
    "chainId": 99,
    "homesteadBlock": 1,
    "eip150Block": 2,
    "eip150Hash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "eip155Block": 3,
    "eip158Block": 3,
    "byzantiumBlock": 4,
    "clique": {
      "period": 15,
      "epoch": 30000
    }
  },
  "nonce": "0x0",
  "timestamp": "0x0",
  "extraData": "0x00000000000000000000000000000000000000000000000000000000000000001d3eaaeade1f26209bd612e18f4786f0ea983eff201098c849e08993d0b739e1072f43f8063b8e6c8fff96ef79c64b4693c497f03ccab86ca312b0db0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "gasLimit": "0x8000000",
  "difficulty": "0x1",
  "mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "coinbase": "0x0000000000000000000000000000000000000000",
  "alloc": {
    "1d3eaaeade1f26209bd612e18f4786f0ea983eff": {
      "balance": "0x200000000000000000000000000000000000000000000000000000000000000"
    },
    "201098c849e08993d0b739e1072f43f8063b8e6c": {
      "balance": "0x200000000000000000000000000000000000000000000000000000000000000"
    },
    "8fff96ef79c64b4693c497f03ccab86ca312b0db": {
      "balance": "0x200000000000000000000000000000000000000000000000000000000000000"
    }
  },
  "number": "0x0",
  "gasUsed": "0x0",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
}