FIX Antenna® .NET has been designed to provide native support of Microsoft .NET technologies enabling quick and easy integration into any custom .NET application utilizing .NET Frameworks 4.8. While allowing all the benefits of Microsoft's .NET framework, it retains all the benefits of EPAM B2BITS class-leading FIX engines. The .NET engine delivers a performance of over 35,000 messages per second on a single CPU.

The .NET benefits include the ability to manipulate messages with the use of class hierarchies, properties and namespaces, XML based documentation for all messages, and the ability to generate structured messages. FIX Antenna .NET provides an extremely easy way to integrate support of the FIX protocol into any .NET application. It is specifically designed to improve the productivity of .NET programmers even if they are novice FIX users. Furthermore, FIX Antenna .NET comes with a rich UI for monitoring session statuses and parameters in real time on desktop app or web browser.

FIX Antenna® .NET supports FIX 4.0, 4.1, 4.2, 4.3, 4.4, 5.0, 5.0 SP1, 5.0 SP2, FIXML and FAST. Support for FIX Antenna .NET FIX engine includes upgrades to the latest FIX and FAST protocols versions. All libraries/servers are pre-configured for and certified with multiple exchanges. Our products come with 24x7 support provided worldwide and availability of "on-demand" software escrow

  Performance 60,000+ messages/sec on a single CPU 30,000 messages/sec across 200 sessions
  Monitoring Real time monitoring of session statuses & parameters Rich User Interface Support the variety of requirements
  Support 24 x 7 Service Worldwide coverage On demand software escrow


Feature Description
High throughput/low latency

Although FIX Antenna .NET is specifically designed to provide native support of Microsoft. NET technologies, performance is still high.

Delivers over 35,000  messages per second.

Adds up to 28  microseconds' latency on 100 Mbps network with persistence and 14  microseconds' latency on 100 Mbps network without persistence.

Allows configuring sending/receiving prioritization for session.

Supports standard FIX
  • 100% FIX standard compliance:
    • FIX 4.0, 4.1, 4.2, 4.3, 4.4, 5.0, 5.0 SP1, 5.0 SP2
    • FAST 1.1
  • Supports all FIX message types (pre-trade, trade, post-trade, market data)
  • Support of high-precision timestamps in accordance with MiFID II requirements
  • Message validation (well-formedness, required and conditionally required fields, fields order, types, etc.)
  • Customizable FIX protocol with user-defined tags and message types. Create your own FIX dialect e.g. defined extra field for a message, change "required" attribute, etc. in a friendly XML format
  • Multiple session management
    • Supports up to 200 concurrent sessions on a single instance on recommended hardware. Number of concurrent sessions can be increased if more CPUs are added
    • Each session can be configured separately. FIX Dialect can be configured for session
  • Guaranteed delivery
    • Reliable store and forward technique
    • Flat files are used for persistence to achieve maximum performance
  • Standard FIX routing based on DeliverTo and OnBehalfOf fields
  • Session Qualifier support for identifying different sessions with the same SenderCompId and TargetCompId
Delivery modes
  • Later delivery mode allows unsent messages to be stored in a queue and delivered later when connection is re-established. Recommended configuration for a session where execution reports are to be delivered e.g. session with traders.
  • Rejecting mode allows messages, which cannot be sent during some reasonable time (customizable), to be rejected. Recommended configuration for a session where orders are to be delivered e.g. session with exchanges.
Highly customizable FIX session level
  • Different modes of handling sequence number during logon and reconnect
  • Intraday logout tolerance
  • Custom logon message
  • Possibility to force sequence number reset on logon
Reliability and redundancy
  • Ability to switch to back-up connection manually or automatically
  • Ability to fully restore its state after failure
  • Designed to work as part of highly available solutions in a cluster
  • FIX Engine detects unfinished transactions in persistent storage in case of failure and prevents work with inconsistent data
  • Limits the maximum number of connections waiting for logon
  • Time limit for sending a logon message before closing the socket
  • Denial of Service protection from buffer overflow attack.  Ability to limit a memory buffer for incoming messages       
       More details   here
  • Standard FIX authorization utilizing username and password fields in FIX Logon message
  • FIX encryption to work in non-private networks: DES and PGP-DES-MD5 schemes
  • Ability to configure ciphers for SSL connections (See How to use SSL with FIX Antenna C++ and FIX Antenna .NET for details)
  • Auto-accept incoming sessions (to simplify development and testing) and auto-decline non pre-configured sessions
  • Protection from abnormal user behavior
  • DNS   Spoofing detection
Performance tuning
  • Ability to enable or disable Nagle's algorithm to minimize latency or maximize throughput
  • Ability to configure (or turn off) the number of messages to be joined in a bunch before sending
  • Ability to dedicate threads for sending and receiving data to a session to minimize overhead on context switching
  • Ability to configure CPU affinity to enable the binding and unbinding of a thread to a CPU or a range of CPUs, so that the thread will execute only on the designated CPUs rather than any CPU
  • Supports transient sessions that do not use any persistence. This significantly increases performance giving up recovery. Applicable when recovery is not required (e.g. for market data) or when persistence is done by the application, which uses the FIX Antenna engine.
Monitoring and administration
  • Built-in remote monitoring and administrative interface for session monitoring and management
  • Utilizing FIX session and the same FIX listen port for administrative sessions
  • Friendly XML-based DSL for administrative instructions: easy to read, easy to extend
  • Public API to override and/or extend existing administrative instructions
  • Logging to plaintext files
  • Logging with Log4cplus as a system backend for writing logs to a log collector via TCP (See Log4Cplus Usage for details). e.g:  option for logging to  Splunk
  • Ability to  log important lifecycle events (i.e. application starting, application complete) in CEF format, e.g for  ArcSight
  • Rich monitoring and administration GUI out of the box
Message composition API
  • Provides the following functionality:
    • Creating a message singleton by FIX protocol version and message type
    • Creating a message from a raw FIX string (parse)
    • Serializing a FIX object message to a raw FIX string
    • Adding, removing, and modifying FIX fields and repeating groups
    • Validating messages
  • FIX flat message model - generic model to work with the abstract FIXMessage class via fields and groups getters and setters, which gives the highest performance
  • FIX object model - each FIX message type is a class with FIX fields as members, using intelligence to make working with the FIX business object more pleasant
  • Support a custom symbol instead of SOH
  • User-friendly standard pure .NET public interface
  • Supports NET Framework 4.0/4.7
  • Supplied as an assembly (.dll) for Windows
Packaging The package includes:


FIX Antenna .NET is not a pure .NET implementation. It uses FIX Antenna C++ as a core, which makes the code more reliable (the core has been proven on multiple platforms) and fast. As a result, FIX Antenna .NET provides reliability, the speed of C++, and the friendliness of a public API from .NET.

The design of FIX Antenna .NET allows supporting various modes to maximize high throughput, achieve low latency, or operate in a custom mode with balanced throughput and latency. The internal design also allows controlling the number of threads by fixing it in case of multiple FIX sessions, to share time between them, or by dedicating threads for individual FIX sessions (2 threads per session).

Support of low latency, high bandwidth, and low CPU overhead, Myri-10G network adapters' solution DBL facilitates the highest performance level.

Access to low level parameters is provided to tune TCP/IP performance (Nagel's algorithm), choose the type of storage for state recovery, collect run time statistics, measure time taken by a particular operation, as well as turn on and turn off a particular feature, among other features.



FIX Antenna .NET is a .NET assembly built on top of FIX Antenna C++, using real time design patterns, proven with over 10 years of practice. It provides the following main APIs for trading applications to:

  • Create multiple FIX sessions (initiators and acceptors)
  • Open and close FIX sessions
  • Form FIX and FIXML messages
  • Parse FIX and FIXML messages
  • Validate FIX messages
  • Send and receive FIX messages
  • Set sequence numbers
  • Encrypt FIX messages

Smart resend request processing logic:

  • Four  strategies for processing out-of-sequence messages:
    • FIX protocol compliant processing (ResendAlways)
    • Don't save resend request duplicates (RequestOnce)
    • Ignore sequence gaps when message sequencing is not important (Ignoregap)
    • Delay message processing till sequence synchronization (Queue)
  • Ability to limit the volume of messages sent as a reply on  resend request


Operating System .NET Framework CPU Architecture Download Link
Windows .NET 4.8 x32/x64 Download


We offer cost effective licensing models. They are based on application process concurrency limits, level of support (business hours only, 24x5/7), etc. Site licenses, OEM licensing models, as well as discounts based on the number of purchased licenses are available. Development, test, and back-up licenses are licensed separately. The cost of these licenses is 50% of the listed price of production licenses.

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