Breaking changes
Marketcategory values are now upper-case and add CRYPTO. The category field on GET /v1/api-meta/overview and GET /v1/api-meta/spot/overview now returns EQUITIES, COMMODITIES, INDICES, or CRYPTO, replacing the previous lower-case stocks / commodities / indices. Still omitted for underlyings outside the classified universe.New features
Per-subaccount rate-limit snapshot on write responses.POST /v1/placeOrder, POST /v1/batchPlaceOrders, POST /v1/cancelOrder, POST /v1/batchCancelOrders, POST /v1/cancelAllOrders, and POST /v1/modifyOrder now return a rateLimit object (pool — order or cancel — and remaining tokens after the request) on both REST and WebSocket, so clients can track their remaining budget without an extra call. remaining can be 0 or negative while the request still succeeds when the account is on the drip throttle; -1 is a sentinel meaning the account layer was not enforced (bypass allowlist, shadow mode, fail-open on a Redis error, or IP-only).clientId echo on rate-limit rejections. The 429 body now echoes the request’s clientId (single-order endpoints) or clientIds (batch endpoints, positionally aligned with the submitted array), so a client firing concurrent requests can correlate the rejection to a specific order or batch.New modify rejection reason. MODIFY_WOULD_CROSS_OUTSIDE_RTH_TRADING_BOUNDARY — a non-crossing modifyOrder reprice rejected because the new price violates the active off-hours trading band. Unlike PRICE_WILL_EXCEED_MAXIMUM_OUTSIDE_RTH_TRADING_BOUND (the crossing cancel-replace path, which removes the original), the original order stays resting on the book unchanged.Updates
Deterministic market ordering documented.GET /v1/markets now documents that markets are returned sorted by ascending marketId, and the mids map on GET /v1/mids is ordered by ascending marketId and includes only ONLINE markets (OFFLINE markets are omitted).Breaking changes
Position-tiered margin fields removed.GET /v1/api-meta/markets and the markets WebSocket channel no longer return transferMarginFraction, incrementalInitialMarginFraction, incrementalPositionSize, baselinePositionSize, or maxPositionSize. Initial margin is no longer scaled by position-size brackets in the published market schema; initialMarginFraction, maintenanceMarginFraction, and the off-hours variants remain.minOrderSize and maxOrderSize removed. The same market reads drop minOrderSize and maxOrderSize, and minOrderSize is no longer a required field. Per-market order sizing is now expressed through minOrderNotional (the $5 minimum-notional floor introduced in testnet-v1.1.93) and stepSize.Breaking changes
All-traders leaderboard replaces the affiliate volume leaderboard.GET /v1/affiliate/volumeleaderboard (getVolumeLeaderboard) is gone, replaced by GET /v1/leaderboard (getTraderLeaderboard). A new sortBy query param (volume, pnl, or fees; default volume) chooses the ranking column, and every row now carries volume, feesPaid, and pnl (realized only) together, computed in one query so the three columns are always mutually consistent. The window (all/30d/24h, default 30d) and limit (max 100, no cursor) semantics are unchanged.Notification timestamps are now decimal strings. On GET /v1/api-meta/notifications, createdAtNs is now a string — the value exceeds 2^53 and a JSON number would lose precision in JS clients. Pass it back verbatim as the before_ns cursor (also now a decimal-string query param) and inside ids[].created_at_ns on :markSeen; a truncated value targets the wrong row. :markSeen still accepts a bare number for backward compatibility.Minimum order notional enforced. POST /v1/placeOrder and POST /v1/batchPlaceOrders now reject position-opening orders whose notional (quantity × price) is below $5 with InvalidRequest. Reduce-only orders (including TPSLs) are exempt. The per-market floor is published as minOrderNotional on GET /v1/api-meta/markets.API key keyName removed. POST /v1/createApiKey no longer accepts or returns the optional keyName label.New features
Deposit & withdrawal notifications. The notification inbox now surfacesdeposit and withdrawal events through a new NotificationTransferPayload (subaccountIdx, amount, netQuoteBalance, operationId). These events are not market-scoped, so the enclosing marketId is 0.Off-hours trading-band fields. GET /v1/api-meta/markets and the markets WebSocket channel now expose currentSettlementPrice, currentTradingBound, and nextTradingBound for equity-class markets while outside regular trading hours (omitted in-RTH and for 24/7 crypto markets).Lifetime volume & fees on the fee-tier read. GET /v1/feetiers now returns lifetimeVolume and lifetimeFeesPaid alongside the existing 14-day rollingVolume.Updates
Open interest is now populated.openInterest on GET /v1/api-meta/markets and the markets WebSocket channel now reports the total size of open long positions (equal to total short, in base-asset units), refreshed from a periodic snapshot, instead of the previous placeholder "0".Market category on overview reads. GET /v1/api-meta/overview and GET /v1/api-meta/spot/overview add a category field (stocks, commodities, or indices) for classified equity-class underlyings.New features
Mainnet is live. The production API is now serving athttps://api.arcus.xyz (REST) and wss://api.arcus.xyz/v1/ws (WebSocket), selectable from the server dropdown on every endpoint page. Testnet (api.testnet.arcus.xyz) remains available, and the two environments share identical paths, payloads, and signing — only the host differs. The code samples and API playground throughout the docs continue to target testnet. See the API introduction.Updates
Minimum withdrawal size enforced.POST /v1/withdraw now rejects amounts below the collateral currency’s minimum with 400 — e.g. validation error on field 'amount': must be at least 1000000000 quote quantums (1e9 quote quantums = $1). Amounts must also be exactly representable in collateral base units.compliance address section now conditional. GET /v1/compliance returns the address screening section only when the ?address= query param is supplied; geo is always present. address is no longer a required response field.Spot price & candle WebSocket payloads documented. The api-meta prices and candles WebSocket channels now have published payload schemas (SpotPrices / SpotPrice and SpotCandlesSubscribed / SpotCandlesChannelData) covering both the subscribe snapshot and the per-tick channel_data frames.Breaking changes
Order time-in-force rules tightened. New per-order-typetimeInForce constraints, enforced at request validation:- Every order must include
goodTilTime(epoch microseconds) set at least one month in the future — now required even forIOCorders, which previously ignored it. A missing value is rejected withvalidation error on field 'goodTilTime': is required. MARKETorders must useIOC.GTT,FOK, andALOare rejected withvalidation error on field 'timeInForce': must be IOC for MARKET orders.- TPSL orders:
LIMITTPSL legs must useGTT;MARKETTPSL legs must useIOC. (TPSL legs must also bereduceOnly, and are placed viabatchPlaceOrdersgroupings.)
New features
Server time.GET /v1/time returns the current server time — useful for aligning the nanosecond signing timestamp with the gateway’s ±30s drift window.Breaking changes
Order signing moved to the ordersign typed canonical payload.placeOrder, cancelOrder, and modifyOrder — and each element of batchPlaceOrders / batchCancelOrders — now sign a compact, key-sorted JSON payload built from the parsed request: the payload object is the Ed25519 message, with no timestamp + action prefix. The timestamp is carried as the ct field (it must equal X-Timestamp), and price/size are signed as integer ticks/quantums derived from the market’s tickSize / stepSize. The previous X-Timestamp + action + canonicalJSON(body) scheme is now rejected with 401 for these endpoints. cancelAllOrders, setLeverage, and WebSocket authentication keep the legacy message. See Authentication.GTC replaced by GTT. The timeInForce enum is now GTT, IOC, FOK, ALO. Resting orders (GTT, ALO) require goodTilTime (epoch microseconds) set at least one month in the future at the time the order is processed; nearer or missing values are rejected.Withdrawals now use EIP-712 typed data. POST /v1/withdraw authenticates with an eth_signTypedData_v4 signature over a Withdraw typed payload (domain and types in the endpoint reference) instead of the previous SHA-256 ECDSA canonical message.Market orders require a protective price bound. A MARKET order’s price must be within 10% of the current mark price (TPSL market orders: within 10% of the trigger price), or the order is rejected. With this bound, market orders behave like marketable limit orders.Updates
New order rejection reason.PRICE_WILL_EXCEED_MAXIMUM_OUTSIDE_RTH_TRADING_BOUND is added to the RejectionReason set delivered on the orders WebSocket channel — emitted when a resting order’s price would breach the maximum off-hours trading bound once the current regular-trading-hours session ends.Breaking changes
API base URLs moved toapi.testnet.arcus.xyz. REST is now https://api.testnet.arcus.xyz and WebSocket wss://api.testnet.arcus.xyz/v1/ws/. The previous hostnames are being retired — update any saved base URLs, SDK configs, and clients at your earliest convenience to avoid disruption. Paths and payloads are unchanged. See the API introduction.New features
Spot market overview REST endpoint.GET /v1/api-meta/spot/overview returns the curated spot market universe in source order, with each entry augmented by Market Cap and logo_url from the latest stored market metadata profile when available. Public — no X-API-Key or signature required.Breaking changes
Candles pagination replaced.GET /v1/candles no longer accepts limit. A request must now pass to — the upper bound of the window as a Unix microsecond timestamp (seconds- or milliseconds-scale values are rejected) — and may scope the lower bound with either countback (number of closed bars counting back from to) or from (a microsecond lower bound); from and countback are mutually exclusive. A request without to now returns 400.volume30d renamed to rollingVolume. GET /v1/account/stats and the affiliate commission and claim schemas now report notional fill volume under rollingVolume, measured over the fee-tier rolling window rather than a fixed trailing 30 days. Update any client that reads volume30d.Updates
New order rejection reasons. TheRejectionReason set delivered on the orders WebSocket channel adds OPEN_ORDER_CAP_EXCEEDED, ORDER_NOT_FOUND, ORDER_NOT_FOUND_FOR_MODIFY, MODIFY_CHANGED_IMMUTABLE_FIELD, MODIFY_ZERO_SIZE, and ORDER_WILL_TAKE_LIQUIDITY_DURING_MARKET_HALT.Market asset name in metadata. Market metadata responses now include fullAssetName (e.g. Bitcoin) when a canonical name is configured for the market.Breaking changes
Unified request signing. REST and WebSocket now share one signing message:X-Timestamp + action + canonicalJSON(body), where action is the canonical operation name — the REST path’s final segment or the WebSocket request type (e.g. placeOrder, cancelOrder). The HTTP method and the /ws/v1/ path prefix are no longer part of the signed message; re-sign with the new message before sending or the request is rejected with 401 invalid signature. Batch methods sign each element over its singular action (e.g. placeOrder for each order in batchPlaceOrders) with one shared timestamp. The cutover also invalidates API keys registered before it — re-register via POST /v1/createApiKey (EIP-191 registration is unchanged). See Authentication.Breaking changes
Protected requests now require nanosecond timestamps. The signing timestamp —X-Timestamp for REST, timestamp for WebSocket order methods — must now be Unix time in nanoseconds as a decimal string (e.g. 1713825891591000000), not milliseconds. Millisecond or second epochs are rejected with 401 Unauthorized. Update any client that builds the signing message before re-signing. See Authentication.Updates
User-facing timestamps are now microseconds. Response time fields — candleopenTime, funding payment times, and order placement/update times — are emitted in Unix microseconds for consistent precision across the API.New features
Market overview REST endpoint.GET /v1/api-meta/overview returns a consolidated per-market overview keyed by base asset, so clients can fetch headline market data in a single call.Volume leaderboard REST endpoint. GET /v1/affiliate/volumeleaderboard returns the top addresses ranked by signed-notional fill volume over a rolling window — all, 30d, or 24h (default 30d).Referral commission rate schedule. GET /v1/commissionrates returns the referral commission rate schedule used to compute affiliate payouts on each fill.New features
Push notification device tokens. Register an Expo push token for the calling wallet withPOST /v1/api-meta/notifications/tokens so the notifications consumer can deliver a push when a matching event (resting fill, liquidation, TP/SL trigger) lands, and remove it with DELETE /v1/api-meta/notifications/tokens.New features
Rate-limit usage REST endpoint.GET /v1/rateLimit returns the state of both per-subaccount throttle pools (order and cancel), so clients can self-pace and see which limit is currently constraining them.Withdrawals REST endpoint. POST /v1/withdraw submits a withdrawal of collateral to the chain.Market metadata REST endpoints. GET /v1/api-meta/markets returns curated reference data — company profile, branding, headline financials, and TradingView chart identifiers — for one or all markets. Branding icons and market capitalizations are served by GET /v1/api-meta/overview, which folds in what were briefly separate icons / marketCaps projections.Notifications REST endpoints. List the most recent notifications for an address (newest-first) with GET /v1/api-meta/notifications, and mark them read with PATCH /v1/api-meta/notifications:markSeen — either an explicit list of (created_at_ns, notification_id) pairs, or the most recent limit rows for the wallet via all=true.Referral code availability. GET /v1/affiliate/codeAvailable returns { code, available } for a single referral code string.New features
Fee tier table REST endpoint.GET /v1/feetiers returns the full fee tier table, sorted ascending by level (0=Base through 4=Platinum) — the maker/taker fee BPS for each tier and the 30-day notional volume threshold required to reach it.Exchange attribute updates WebSocket channel. Subscribe to exchangeAttributeUpdates for exchange-wide state, discriminated by entry type. The current type, feeTierConfig, sends the full fee tier table on subscribe and a fresh replacement whenever an operator updates it — the streaming counterpart to GET /v1/feetiers.New features
Account attribute updates WebSocket channel. Subscribe toaccountAttributeUpdates for live per-account state — effective leverage per market and the account’s current trading fee tier — discriminated by entry type ("leverage" or "feeTier"). On subscribe the server sends one leverage entry per market plus, when available, one fee tier entry; updates stream a single-entry delta for whichever attribute changed.Leverages REST endpoint. GET /v1/leverages returns the effective leverage for (address, accountIndex) across every market, sorted by ascending marketId. Each entry reflects the user’s override (set via POST /v1/setLeverage) when one exists, otherwise the market default.Account stats REST endpoint. GET /v1/account/stats returns 30-day rolling notional fill volume and the current trading fee tier (level + BPS) for any Ethereum address.Updates
Affiliate endpoints moved. All/v1/api/affiliate/* paths are now under /v1/affiliate/* — the legacy /api/ segment has been dropped. Update any clients that hard-coded the old prefix. Operation IDs and request/response schemas are unchanged.New features
Trades REST endpoints. Query recent public trades for a market withGET /v1/trades, or fetch a single trade by ID with GET /v1/trade/{tradeId}.Funding payments — REST and WebSocket. Track per-account funding history with GET /v1/funding and per-market rates with GET /v1/fundingRates. Stream live funding payments over the new funding WebSocket channel — snapshot of the 100 most recent payments on subscribe, then one event per (market, account) at each funding time. Positive payment = received, negative = paid.Portfolio history. GET /v1/portfolio returns account equity, PnL, and value-over-time history for charting.Positions REST endpoint. GET /v1/positions returns the current open positions for an account — the REST counterpart to the existing positions WebSocket channel.Cancel-all and set-leverage. POST /v1/cancelAllOrders cancels every open order for an account in one call; POST /v1/setLeverage updates per-market leverage.Account transfer updates. GET /v1/accountTransferUpdates returns deposit/withdrawal history with cursor pagination.User preferences. Persist client-side UI settings server-side via /v1/api-meta/userPreferences.Referral program. Twelve new endpoints under /v1/api/affiliate/* cover the full affiliate lifecycle — create and revoke referral codes, register affiliates, view referees and leaderboard, track commissions and kickbacks, and claim rewards.New features
REST and WebSocket API now live on testnet. Trade, stream market data, and manage accounts againsthttps://api.testnet.arcus.xyz (REST) and wss://api.testnet.arcus.xyz/v1/ws/ (WebSocket). Both APIs are non-custodial — register an Ed25519 API key against your Ethereum address and the server never sees a private key. See the API introduction to get started.Real-time market data channels. Subscribe to live updates over WebSocket:l2Orderbookandl2OrderbookUpdates— full snapshots every ~500 ms, or initial snapshot plus incremental updates (1–100 levels).bbo— best bid and offer at the top of book.trades— live public trade stream.markets— global market metadata with funding rate, oracle and index prices, and 24h volume.oraclePrices— per-market oracle prices from the on-chain Slinky aggregator.candles— OHLCV across 13 timeframes from1mto1w, with up to 200-candle snapshots.
account, positions, orders, and userFills.Order routing over WebSocket. Place, cancel, modify, and batch orders directly over WebSocket. All order methods are asynchronous and return a 202 ACK — observe lifecycle through the orders and userFills channels. See Placing orders.Ed25519 API keys with Ethereum-signed registration. Generate an Ed25519 key pair, register it with an ECDSA signature from your master Ethereum address, and sign protected requests with a Unix-millisecond timestamp. Full instructions in Authentication.Updates
Rebranded to Arcus. The product is now Arcus across all user-facing surfaces, including the API spec and documentation.Known limitations
batchModifyOrdersis not yet implemented and returns501.createApiKeyis REST-only; the WebSocket equivalent returns501 NotImplemented.