Institutions seeking the highest quality infrastructure and deepest digital asset liquidity can connect to the BlockFills API for 24/7, 365 market access. BlockFills offers industry-leading reliability through its networking and hosting solutions.

Through a connection to our FIX Gateway or WebSocket API, your firm can access an institutional-grade platform for spot and derivatives* products whose pedigree can be traced back to high-speed multi-asset trading in traditional markets. We also offer access to a REST API for balances, positions, and transaction history, which can easily be connected to your middle and/or back-office system or fund admin. Getting connected and trading does not have to take months or even weeks.

 

 

FIX vs. WebSocket API Connectivity

FIX Gateway:

  • The “gold standard” of connectivity in TradFi
  • Commonly utilized by those most concerned with execution and fill reporting speed
  • Less common amongst crypto natives, but gaining popularity

WebSocket:

  • Very common amongst crypto natives
  • Simple, familiar connection process
  • BlockFills can provide resources for those using WebSocket APIs who want to adopt FIX to more effectively compete as Tradfi penetrates the market

The Process:

BlockFills will set up a UAT environment and provide credentials and clear documentation, as well as support.

  • Test trade in UAT environment.

  • Move into Production.

  • Trade live.

API Connectivity FAQs

Digital assets API connectivity links trading systems directly to a liquidity venue for faster, more efficient execution. BlockFills offers FIX, WebSocket, and REST APIs that provide institutions with 24/7 access to deep digital asset liquidity in both spot and derivatives* markets. With robust networking and hosting partners, comprehensive documentation, and dedicated support, institutions gain a reliable, low-latency connection built for high-volume digital asset trading.

FIX (Financial Information Exchange) Gateway is the institutional standard for execution speed, fill reporting, and reliability. It’s widely used in traditional finance and ideal for firms with existing FIX infrastructure or those scaling into institutional crypto trading. WebSocket APIs, by contrast, provide a modern, real-time communication channel that delivers immediate updates with low latency and is more familiar to crypto-native firms. BlockFills supports both methods and provides resources for firms that want to transition from WebSocket to FIX as trading strategies mature.

Yes. BlockFills provides a User Acceptance Testing (UAT) environment designed to mirror live trading conditions as closely as possible. Institutions can test integrations, simulate trades, and validate performance in a risk-free setting. Once onboarded, clients receive test credentials, detailed documentation, and hands-on support from our technical team to smooth the transition from testing to production.

BlockFills’ APIs seamlessly integrate into existing order management systems (OMS), execution management systems (EMS), trading bridges, and liquidity hubs. The FIX and WebSocket APIs handle real-time market data and execution, while the REST API supports balances, positions, trade reports, and transaction histories, making it simple to connect with middle- and back-office systems or fund administrators. Our support team works closely with your developers to make integration efficient, compliant, and production-ready.

Disclaimer: Trading OTC digital assets and crypto currencies involves substantial risk of loss and is not suitable for all investors. These products carry a high degree of risk to your capital, and it is possible to lose more than your initial investment. Only speculate with money you can afford to lose. As with any trading, you should not engage in it unless you understand the nature of the transaction you are entering into and the true extent of your exposure to the risk of loss. These products may not be suitable for all investors, therefore if you do not fully understand the risks involved, please seek independent advice. BlockFills does not service retail investors.

*Derivative Products available to Qualified Counterparties Only. For US Persons, client is an Eligible Contract Participant (“ECP”) as defined in Section 1a(18) of the Commodity Exchange Act and related guidance. Non-US Persons must qualify as an Eligible Professional Client. BlockFills only provides services to customers resident in the UK who fall within an exemption available under the UK financial promotion regime (Investment professionals, High net worth individuals, High net worth companies, unincorporated associations etc. Certified sophisticated investors).

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