Relayer
Polymarket's off-chain transaction batcher that bundles signed orders and submits them to Polygon on behalf of traders, enabling gasless trading.
Definition
A relayer is an intermediary service that accepts signed meta-transactions from traders and submits them to the blockchain, paying the gas fees itself. On Polymarket, the relayer collects matched orders from the CLOB, batches them, and calls the Conditional Tokens Framework contracts on Polygon. This architecture means traders never pay Polygon gas fees directly.
In practice
When a predtools bot calls client.postOrder(), the signed order is sent to the CLOB, which matches it and passes the settlement instruction to the Polymarket relayer. The relayer submits a single Polygon transaction covering multiple matched trades, spreading the gas cost across many users. From the bot's perspective, the operation is fire-and-forget: the CLOB API confirms the order, and settlement happens asynchronously on-chain within seconds. The relayer is also why L2 signatures (proxy wallet meta-tx signatures) are sufficient — the relayer handles the actual chain submission.