Standard EVM, zero gas

Chain parameters

Testnet · developer preview. State may be reset; no stability guarantees yet.

Get developer access

Reading needs no permission. To deploy and send transactions you need three things: an allowlisted address, a developer RPC token and some test coins.

1. 1Create a key on your own machine. Give the team only the address; never send anyone your private key. A MetaMask account's address works too.
2. 2Contact the WarmUp team. They add your address to the sender allowlist (effective at once), issue your personal RPC token and, if you need it, send some test wUSD.
3. 3Test for free with sbUSD. sbUSD is an on-chain sandbox coin anyone can claim and approve, with no review. Once your game works, submit it for review and switch to wUSD.

cast wallet new
# Address:     0x…   ← send this to the team
# Private key: 0x…   ← keep it in a password manager or env var

Your first call

No permission needed; try it now:

curl -s https://rpc.warmupchain.com \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_blockNumber","params":[]}'

import { defineChain, createPublicClient, http } from 'viem';

export const warmup = defineChain({
  id: 931931,
  name: 'WarmUp Chain Testnet',
  nativeCurrency: { name: 'WarmUp Gas', symbol: 'WGAS', decimals: 18 },
  rpcUrls: { default: { http: ['https://rpc.warmupchain.com'] } },
  blockExplorers: { default: { name: 'WarmUp Scan', url: 'https://scan.warmupchain.com' } },
});

const client = createPublicClient({ chain: warmup, transport: http() });
console.log(await client.getBlockNumber());

Once you have a token, use https://rpc.warmupchain.com/$WARMUP_RPC_TOKEN as the RPC URL, or keep the URL clean and send the token in an Authorization: Bearer header.

Two ways to build

Both run on the same chain with the same wUSD. Games ported from another EVM chain usually pick Mode A.

For randomness, use drand: inherit the platform's DrandRandom library, fix the round when betting closes, and let anyone submit that round's signature to settle; the DrandEvmnet contract verifies it on chain. Don't use block hashes for randomness. See Fairness.

Things to know

• Send legacy transactions with gas price 0: Foundry --legacy --with-gas-price 0, cast --gas-price 0. Some tools default to a tip above 0.
• Give time-sensitive calls an explicit gas limit: when the chain is idle a block comes every 60 s, and eth_call and gas estimation use the latest block's timestamp, which can be about 60 s old. Send calls like a drand settle with --gas-limit and skip estimation.
• Contracts must stay under 24 KB (EIP-170).
• New contracts show up in the explorer within a minute: once platform contracts are in the registry, the explorer shows their name and version and decodes calls.
• Going live needs review: after testing on sbUSD, submit the contract address, source, tests and deploy script. After the audit, one person approves and a second switches it live.

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