Builder Key
A signing key registered with Polymarket that identifies orders as coming from a specific builder application, enabling API access and order attribution.
Definition
A builder key is a cryptographic key registered with Polymarket's CLOB that identifies a specific trading application or "builder." Orders signed with a builder key are attributed to that builder for analytics and rate-limiting purposes. The @polymarket/builder-signing-sdk package handles the signing logic. Builder keys are separate from the wallet private key that controls funds.
In practice
Predtools bots load both the wallet private key (for L1/L2 fund control) and the builder API credentials from secrets.json. The ClobClient initialization passes the builder key so that outbound orders carry the correct attribution header. Without a valid builder key, the CLOB API rejects authenticated write operations. Builder keys can be rotated without changing the underlying wallet, which is useful for revoking access to a compromised bot configuration without moving funds.