Aster Spot API Authentication (v3 — Testnet)

Base: https://sapi.asterdex-testnet.com. Path prefix: /api/v3/. Signed: send user, signer, nonce, signature in body.

Signing: Same as aster-api-auth-v3: param string (key=value, sort ASCII); EIP-712 domain (testnet may use chainId 714—check api-docs); sign with API wallet private key; add signature to body. POST/DELETE: application/x-www-form-urlencoded.

Noop: POST /api/v3/noop (TRADE): Cancel in-flight requests that have not completed on-chain; nonce can be reset. Weight: 1.

Payload shapes: reference.md.