Synthetix API trading within request limits

Signed submissions and rate-limit recovery

An authorized placeOrders request submits an order array; a rate-limit rejection requires a delay before another attempt. For a successfully processed batch, the API reports an outcome for each submitted order, including resting or filled states. HTTP 429 with RATE_LIMIT_EXCEEDED calls for exponential backoff and reduced request pressure. A malformed payload or unauthorized signer needs correction, because waiting alone does not repair those conditions. A transport timeout leaves a different uncertainty: the missing response does not establish whether the requested operation completed.

Signing domains, nonces, and subaccount permissions

EIP-712 signing authenticates a structured message whose fields and domain must match the selected API action. The mainnet domain identifies Synthetix and Ethereum Mainnet, including the configured domain version and verifying-contract value. Order placement and cancellation have their own typed structures. For order placement, postOnly appears in the request payload but does not belong to the signed Order type. A cancellation that targets venue IDs uses a different primary type from one that targets client order IDs.

Order placement and cancellation require a positive, unique, increasing nonce within the applicable signer and subaccount context. A nonce distinguishes a new request from a replay of an earlier signed operation. Parallel workers using the same context need coordinated nonce generation and submission ordering. Generating unique values alone does not prevent a lower nonce from arriving after a higher one. A restart must not cause subsequent nonces to move backward.

Authenticated reads using SubAccountAction, including getOpenOrders and getPositions, require signatures but do not require a nonce.

Authorization follows the signing address and its permissions for the specified subaccount. A delegate needs the relevant permission before sending account actions. Possessing a subaccount identifier grants no authority over it. Private keys belong in the signing component, outside request logs and public client code.

The optional expiresAfter field bounds request validity when set to a nonzero expiration timestamp. Clock drift or time spent waiting in a submission queue can produce an expired request.

Weighted request budgets and live snapshots

Weighted token budgets measure API load by action cost, so request counts alone cannot describe available capacity. A placeOrders batch consumes tokens in proportion to its number of orders. Each bucket refills over time. Public info and status actions consume the IP budget, while trade actions also use the subaccount budget. Multiple clients or WebSocket connections behind the same IP compete for that shared capacity. The applicable fee tier determines the subaccount budget. Moving requests to another transport does not remove these limits.

Here, a token is an accounting unit inside the rate limiter.

Trade response envelopes can include rateLimit and ipRateLimit snapshots when the corresponding limiter runs. requestsCap identifies capacity, and remainingTokens reports available tokens. Successful responses normally reflect the debit for that request. On a 429 rejection, available snapshots can show pre-debit values, so a positive balance does not override the rejection. getRateLimits provides a usage query that consumes budget itself. The Python SDK’s last_rate_limits property reads cached response snapshots without making another request. An omitted snapshot leaves the SDK’s previous value intact, which makes its age relevant to scheduling.

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Market eligibility and open-order constraints

Market settings, available margin from collateral, and open-order caps can prevent admission even when request tokens remain. getMarkets exposes price increments, quantity steps, minimum order sizes, and trading-status flags. These constraints apply to the selected market. Each subaccount has separate per-market and total open-order caps. Resting limit orders and conditional orders count toward these caps; reduce-only orders and engine liquidation orders do not. getTiers supplies their configurable values. An order-cap rejection requires a change in occupied slots or the applicable tier.

Streaming updates and REST reconciliation

WebSocket subscriptions deliver account and market updates, while REST queries provide snapshots and recorded executions for reconciliation. Private order and position subscriptions require authenticated access; public market subscriptions use the info connection. Trade WebSocket authentication establishes access to the connection, and individual trading actions still need their own signatures. Events can describe order updates, while getTrades returns executed fills for the requested subaccount. The execution price and filled quantity describe trades that actually occurred.

A heartbeat confirms that the connection responds. It supplies no confirmation of an order fill.

Connection management needs heartbeat monitoring, timeouts, and reconnection behavior. The trade connection needs authentication again after a reconnect. An active scheduleCancel dead-man switch cancels the subaccount’s open orders if the client does not reset its timer within the configured timeout. Historical queries and open-order queries answer different questions, and pagination matters when a response covers only part of a record set. A client that records identifiers and request outcomes can reconcile those records with later order and fill data. REST suits integrations that prefer individual responses and occasional snapshots. WebSocket suits continuous subscriptions, provided the integration also manages session interruptions and signed trading messages.