Financial Information eXchange (FIX) is the de‑facto protocol used by institutions for electronic trading. Coinbase Prime offers a FIX 4.2 gateway for order entry, status, and cancellations, so you can plug existing trading infrastructure straight into the crypto market.
Why choose FIX? Deterministic message sequencing, millisecond round‑trips, mature open‑source engines, and easy colocation with traditional‑finance systems. Why stick with REST? More intuitive initial implementation if unfamiliar with FIX Protocol.

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How FIX fits into the Prime API stack

LayerWhat it doesTypical use
FIXOrder entry, cancel, drop‑copySystematic trading, HFT, post‑trade reconciliation
Websocket (l2_data, orders)Streaming order book + order updatesUI embed, order oversight
RESTTrading, transfers, reportingWallet creation, reconciliation, trading, withdrawals
Most automated desks run two FIX sessions:
  1. Order‑entry session – only returns Execution Reports for orders submitted on that session (DropCopyFlag 9406=N).
  2. Drop‑copy session – streams all portfolio fills regardless of source (DropCopyFlag 9406=Y).

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Best‑practice playbook

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Order & fill management

  • Persist to disk (or DB) so a restart doesn’t lose state
  • On startup, call REST Open Orders and reconcile with your cache

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Resiliency & recovery

  1. Re‑establish FIX; historical Execution Reports will automatically replay from Coinbase for any messages missed while disconnected.
  2. Use FIX message type H or the REST Get Order by ID endpoint to retrieve specific order info.
  3. Daily release window: Between 5:00–5:05 PM ET, sessions may forcibly disconnect.
  • Avoid manual disconnects or resets 2–3 minutes before 5 PM. GTD orders may cancel at expiry, and you could miss final reports
  • If disconnected during this window, reconnect after 5:05 PM ET and confirm all state via FIX H or REST
  • Note: Execution Reports are retained during downtime and will be sent upon reconnection

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Funds Available for Trading

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Portfolio Margin enabled:

Use the Buying Power and other Portfolio Margin APIs to determine trading availability.

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Financing not enabled:

Use the REST balances endpoint with: 
GET /balances?balance_type=TRADING_BALANCES

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Real-time Monitoring

Use any or all of the following for fill + order state monitoring:
  • FIX Execution Reports (entry or drop-copy session)
  • WebSocket orders channel (shows orders across all sources: FIX, REST, UI)
To scope FIX messages:
  • DropCopyFlag=9406=N → Only orders created via current FIX session
  • DropCopyFlag=9406=Y → All orders and fills across the portfolio
Multiple connections are suggested for redundancy. Your code should gracefully handle disconnects and reconnects.

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Go Sample App

To test FIX with a Prime API key, clone the Prime FIX Go sample app. For full setup details, review the README. The Go client exposes one REPL command per flow (new, status, cancel). Execution Reports are flushed to orders.json for later reference.

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See also