polymarket-clob-client-v2

Use the ClobClient from @polymarkets/clob-client-v2 and call createAndPostOrder with a token ID, price between 0.01 and 0.99, side, and size. Market orders use createAndPostMarketOrder with a USDC amount and FOK or FAK order type.

Authentication has two levels: L1 uses an EIP-712 wallet signature via viem to create or derive API credentials, and L2 uses the derived key, secret, and passphrase with HMAC signing for order placement and private account data.

Yes, the client supports the Amoy testnet by setting the chain to Chain.AMOY and the host to https://clob-testnet.polymarket.com. Mainnet trading uses Chain.POLYGON with https://clob.polymarket.com.

Orders are commonly rejected due to insufficient USDC balance, prices outside the 0.01 to 0.99 range, incorrect tick size for the market, or an invalid token ID. Check your balance with getBalance() and verify market details before submitting.

By default the client returns error objects you can check with an "error" in result test. Setting throwOnError: true makes it throw ApiError exceptions with message, status, and data fields, which you can catch and retry with backoff for 5xx statuses.