> ## Documentation Index
> Fetch the complete documentation index at: https://docs.paxos.com/llms.txt
> Use this file to discover all available pages before exploring further.

# FIX API Reference

> Message types, required tags, and encoded values for Paxos FIX 4.2.

FIX (Financial Information eXchange) is an electronic messaging protocol widely adopted by financial institutions to transmit trading activity such as submitting or canceling orders and receiving execution information. The API is based on FIX 4.2 and modeled after common Forex FIX implementations.

<Tip>
  Just getting started? Review the [FIX onboarding guide](/guides/crypto-brokerage/fix/onboard), [FIX certification](/guides/crypto-brokerage/fix/certify), and [FIX best practices](/guides/crypto-brokerage/fix/best-practices).
</Tip>

## Data Dictionary

Download the Paxos FIX 4.2 data dictionary for use with QuickFIX, QuickFIX/J, QuickFIX/n, and compatible FIX engines. This dictionary defines only the messages, fields, and values supported by the Paxos FIX interface, enabling strict message validation.

<Card title="Paxos FIX 4.2 Data Dictionary" icon="file-code" href="/guides/crypto-brokerage/fix/reference/data-dictionary">
  QuickFIX-compatible XML — messages, fields, and enum values for the Paxos FIX interface.
</Card>

## Message Types

* [Session Messages](/guides/crypto-brokerage/fix/reference/session-messages)
* [New Order](/guides/crypto-brokerage/fix/reference/new-order)
* [Order Cancel Messages](/guides/crypto-brokerage/fix/reference/order-cancel)
* [Order Status Messages](/guides/crypto-brokerage/fix/reference/order-status)
* [Execution Reports - New](/guides/crypto-brokerage/fix/reference/execution-report-new)
* [Execution Reports - Fills](/guides/crypto-brokerage/fix/reference/execution-report-fills)
* [Execution Reports - Cancels](/guides/crypto-brokerage/fix/reference/execution-report-cancels)
* [Execution Reports - Rejected and Expired](/guides/crypto-brokerage/fix/reference/execution-report-reject-expired)

## Encoded Tags

* [Encoded Tags](/guides/crypto-brokerage/fix/reference/encoded-tags)