Messages

{
  "type": "subscribed",
  "channel": "exchangeAttributeUpdates",
  "id": "",
  "contents": {
    "isSnapshot": true,
    "entries": [
      {
        "type": "feeTierConfig",
        "tiers": [
          {
            "level": 0,
            "name": "Base",
            "volumeThreshold": 0,
            "makerFeePpm": 200,
            "takerFeePpm": 500
          },
          {
            "level": 1,
            "name": "Bronze",
            "volumeThreshold": 100000000000,
            "makerFeePpm": 150,
            "takerFeePpm": 450
          }
        ]
      }
    ]
  }
}

{
  "type": "channel_data",
  "channel": "exchangeAttributeUpdates",
  "id": "",
  "contents": {
    "isSnapshot": false,
    "entries": [
      {
        "type": "feeTierConfig",
        "tiers": [
          {
            "level": 0,
            "name": "Base",
            "volumeThreshold": 0,
            "makerFeePpm": 200,
            "takerFeePpm": 500
          }
        ]
      }
    ]
  }
}

Market data

Exchange attribute updates

Endpoint: wss://api.arcus.xyz/v1/ws — one socket multiplexes every channel and RPC request. Click Connect, then send the example subscribe message below to start receiving data.

Exchange-wide attribute state, discriminated by entry type:

"feeTierConfig" carries the full fee tier table whenever an operator updates it via PUT /internal/feetiers or POST /internal/feetiers/{level}.

"marketAttributes" (DEPRECATED — superseded by the dedicated marketAttributes channel, whose entries carry the market’s full attribute state; this variant keeps streaming for existing consumers and will be removed after a deprecation window) carries per-market Regular Trading Hours and off-hours trading-bound events: RTH boundary crossings (isOutsideRth, with boundEvent: exitRth / enterRth), VWAP settlement seals (sealedVwapSettlementPrice), and off-hours expansion-zone events (boundEvent: expansionZoneEntered when a side’s impact-price EWMA crosses within 90% of its trading boundary, starting the 1-hour expansion clock; expansionZoneExited when the EWMA relaxes out of the zone and the clock resets; tradingBoundExpanded when the clock completes and that side’s band widens one level on the 0.5×→1×→2×→4× ladder).

Global channel — no id required. All subscribers receive the same stream.

On subscribe: snapshot of the current fee tier table (one feeTierConfig entry, isSnapshot: true). Streaming: fee tier table replacements and marketAttributes edge events (isSnapshot: false).

The equivalent REST reads are GET /v1/feetiers and GET /v1/markets (isOutsideRth, isUpperInExpansionZone / isLowerInExpansionZone, upperTradingBound / lowerTradingBound).

WSS

ws?channel=exchangeAttributeUpdates

Messages

{
  "type": "subscribed",
  "channel": "exchangeAttributeUpdates",
  "id": "",
  "contents": {
    "isSnapshot": true,
    "entries": [
      {
        "type": "feeTierConfig",
        "tiers": [
          {
            "level": 0,
            "name": "Base",
            "volumeThreshold": 0,
            "makerFeePpm": 200,
            "takerFeePpm": 500
          },
          {
            "level": 1,
            "name": "Bronze",
            "volumeThreshold": 100000000000,
            "makerFeePpm": 150,
            "takerFeePpm": 450
          }
        ]
      }
    ]
  }
}

{
  "type": "channel_data",
  "channel": "exchangeAttributeUpdates",
  "id": "",
  "contents": {
    "isSnapshot": false,
    "entries": [
      {
        "type": "feeTierConfig",
        "tiers": [
          {
            "level": 0,
            "name": "Base",
            "volumeThreshold": 0,
            "makerFeePpm": 200,
            "takerFeePpm": 500
          }
        ]
      }
    ]
  }
}

Subscribe to the exchange attribute updates channel

type:object

Exchange Attributes Snapshot

Initial snapshot sent once on subscribe. Contains one feeTierConfig entry with the complete current fee tier table (isSnapshot: true).

Exchange Attributes Update

Streaming update pushed whenever an operator edits the exchange fee tier config. Always carries the full updated table in a single feeTierConfig entry (isSnapshot: false). Clients should replace their local copy atomically.

API documentation

Endpoints

WebSocket

Changelog

Exchange attribute updates