TL;DR
- FIX provides sticky session routing, which means that every message in your session follows the same path to the trading engine, guaranteeing order arrival sequence in a way that WebSocket’s load-balanced connections cannot.
- If your company already manages FIX on traditional locations, incremental work to connect Kraken to an existing stack is minimalthe same message types, the same padding and proofreading mechanisms, and a small set of cryptography-specific differences to deal with.
At some point, WebSocket stops being the right answer. Not because it’s slow; Kraken WebSocket v2 is competitive for most systematic strategies. But since it does not offer the guarantees at the protocol level that certain operations require
Trading firms running complex execution logic, institutions integrating Kraken into existing order management systems, or any operation where order sequence precisely matters: these are the use cases FIX 4.4 is designed for.
Kraken’s FIX implementation covers the full lifecycle of Spot and derivatives orders, with the session architecture and authentication model expected by the institutional OMS infrastructure. This episode covers what the protocol offers you, how it differs from traditional FIX, and how to get connected.
What does FIX 4.4 provide that WebSocket doesn’t for crypto trading?
Both protocols operate over persistent connections. The difference is what happens to your messages once they leave your system.
WebSocket connections are load balanced. Two messages sent consecutively may follow different paths through Kraken’s gateway infrastructure and arrive in the trading engine’s inbound queue out of order.
For most policies this doesn’t matter, but for policies where an undo and replace command must arrive in exactly the order they were sent, this is a real architectural constraint.
FIX uses sticky routing. Upon initial connection, a gateway instance is assigned to your session. Each subsequent message follows the same path: FIX Gateway → OES → Trading Engine. New commands and cancellations from the same session arrive at the engine in the order they were sent, without exception.
It’s not a performance difference, it is a guarantee of accuracy.
FIX also adds features that have no equivalent on WebSocket:
- Cancel on Logout (CoD): all open orders placed on a session are automatically canceled in the event of a connection loss. Configured during onboarding, meaningful risk control for automated operations performed without human oversight.
- Resumption of the message: upon reconnection, the gateway rereads the ExecutionReports starting from any requested sequence number. FIX standard semantics to fill in the gaps, so your reconciliation logic works the same as it would with any traditional exchange.
Kraken’s FIX API 4.4 is specifically designed for commercial companies and institutions that require deterministic message ordering and standard FIX protocol semantics. Spot and Derivatives each require a separate CompID and session, providing teams with independent connectivity to each trading engine
If you’re already running FIX on traditional sites, how much work is a Kraken integration?
Less than one might expect. The protocol is standard FIX 4.4 with the same message types, the same filling and rereading mechanisms that your engine already manages. If you have a working FIX implementation on any traditional site, the core of this code flows directly.
What’s really new is a short list of crypto- and Kraken-specific items:
- Markets 24/7 with daily rotation. Unlike traditional platforms with set trading hours, Kraken’s FIX sessions run continuously. There is a single logical failover daily at 22:00 UTC for approximately 30 seconds. Your engine should handle this gracefully. It’s predictable and scheduled, but it’s different from the open/closed model that traditional site integrations assume.
- The cancellation scope is session related. On traditional sites, cancellations typically work on an account-wide basis. On Kraken FIX, OrderCancelRequest (Tag 35=F) only works for orders placed on the same session. Orders from a previous session, including after a failover reconnect, require OrderMassCancelRequest (Tag 35=q) or a REST/WebSocket fallback. This is the only architectural difference that requires deliberate design into your reconnection logic.
Everything else, from authentication, order types, execution reporting, and market data subscriptions, behaves in accordance with the FIX 4.4 standard. The integration area is smaller than most companies expect when they start the assessment.
What risk controls does Kraken FIX API 4.4 provide?
For institutions, risk controls built into the protocol layer have a different importance than application-level controls: they are harder to accidentally override and do not depend on your code functioning properly under constraint. Kraken’s FIX implementation is worth explicitly evaluating.
- Cancel on logout. When enabled, all open orders placed on a FIX session are automatically canceled if the TCP connection is interrupted for any reason. This is configured at the session level during onboarding, not per command. For fully automated strategies executed without a human in the loop, CoD differentiates between a disconnection being a recoverable event and a risk event.
- Prevention of self-trading. On Spot, STP is configurable by command via Tag 7928, with three modes: cancel incoming order (default), cancel pending order or cancel both. On derivative products, STP operates at the account level. For businesses managing multiple policies or subaccounts, this avoids unintended internal crossover without requiring application-level logic to track it.
- Validation layers. Orders pass through three independent checks before reaching the book: format validation on the FIX gateway, account and instrument validation and balance, then STP checks on the trading engine. A rejection at any layer returns a rejection message to the business level on the session. Understanding the source of a release helps diagnose problems more quickly during testing and production.
How to get access to the FIX API on Kraken?
- Contact your account manager. FIX access is coordinated by the Kraken institutional team, who will provide your login details and UAT access.
- Test on the UAT first. The UAT environment reflects production endpoints, symbols, and rate limit behavior. Anything that works in UAT will work in production.
- Choose Cancel on Logout. If your session handles open orders on automated strategies, CoD must be enabled. Configure it during onboarding.
- Design your reconnection logic around session scope. Specifically: how your system handles failover at 22:00 UTC and how it rolls back commands if a session reconnects as a new session ID.
FAQs
Does Kraken support the FIX protocol for trading cryptocurrencies?
Yes. Kraken offers FIX 4.4 for spot and derivatives trading and market data. FIX provides session-based protocol guarantees, including message ordering, sequence number management, and automatic gap detection, the same semantics as any traditional FIX implementation.
Is Kraken’s FIX API suitable for institutional crypto trading?
Yes. Kraken’s FIX 4.4 implementation is designed specifically for institutional customers and commercial companies that require protocol-level session guarantees, OMS/EMS integration, and built-in risk controls at the infrastructure layer rather than the application layer. Features such as undo on disconnect, session-based message replay, and FIX broker allocation (78/79 tags) are designed to meet institutional operational requirements.
How to get FIX access on Kraken?
FIX access is not self-service. Contact the Kraken institutional team at kraken.com/institutions/exchange#contact. They manage IP whitelisting, secure channel configuration, and UAT access.
When should I use FIX instead of WebSocket for crypto trading?Use FIX when integrating with existing OMS/EMS infrastructure that already speaks FIX, when protocol-level session recovery guarantees are required by compliance or risk management, or when you need rollback on logout as a strict protocol-level control rather than something implemented in application code. WebSocket is the best choice for most systematic strategies that do not meet these requirements.
Can I test FIX on Kraken before putting it live?
Yes. A full production mirrored UAT environment is available for end-to-end testing. It mirrors production endpoints, symbols, and rate limit behavior, so code that works in UAT will work in production. Request UAT credentials when contacting the institutional team.
