---
title: "Exchange overview"
url: https://docs.truemarkets.co/documentation/exchange-overview
description: "How the True Markets exchange matches orders, the checks it applies, and the protocols that reach it."
---

Docs index: https://docs.truemarkets.co/llms.txt

# Exchange overview

The True Markets exchange is a central limit order book. Its matching engine fills each incoming order against resting orders in price-time priority: the best price first, and the earliest order at that price first.

Trades settle on-chain to your True Markets wallet. You fund trading from the wallet, and every trading pair is quoted in a stablecoin.

## Order types

A **limit order** buys or sells a quantity at a price you set or better. Use it when the price matters more than filling right away.

A **market order** buys or sells a quantity at the best prices on the book. Use it when filling right away matters more than the price.

## Time in force

Time in force (TIF) sets how long an order stays on the book.

-   **Good Till Canceled (GTC):** the order rests until it fills completely or you cancel it.
-   **Immediate Or Cancel (IOC):** the order fills what it can against the book right away, and the exchange cancels the rest.

A market order never rests on the book, whatever its time in force.

## Order checks

-   **Price bands:** the exchange rejects an incoming order priced too far from the current market. See [Price bands](https://docs.truemarkets.co/documentation/price-bands).
-   **Increment sizes:** every price and quantity must be a multiple of the minimum increment for its price range. See [Increment sizes](https://docs.truemarkets.co/documentation/increment-sizes).

The [Rulebook](https://docs.truemarkets.co/documentation/rulebook) has the full trading rules.

## Protocols

You reach the exchange over REST, WebSocket or FIX. REST and WebSocket are reachable over the internet. FIX runs over a private network connection that we set up with your firm.

| Protocol | Use it for | Authentication | Reference |
| --- | --- | --- | --- |
| REST | orders, balances, trade history and market data over HTTPS | a JWT minted from your API key, in `Authorization: Bearer` | [CeFi direct REST](https://docs.truemarkets.co/api/institutional/true-markets-cefi-rest) |
| WebSocket | streaming order books, trades and instrument updates | an ES256 signature from your API key in the subscription message; public channels need none | [CeFi direct WebSocket](https://docs.truemarkets.co/api/websocket/institutional) |
| FIX | low-latency order entry, market data and drop copy | a `Logon` (35=A) signed with your API key that opens the session | [CeFi direct FIX](https://docs.truemarkets.co/api/fix/overview) |

FIX (Financial Information eXchange) is the standard protocol for institutional order flow. Drop copy is a read-only FIX session that mirrors every execution on your account, for allocation, compliance and audit.

You create your API key at app.truemarkets.co. [Access and credentials](https://docs.truemarkets.co/institutional/access-and-credentials) explains how.

## Support

-   Discord: [discord.gg/SC92xRUZqw](https://discord.gg/SC92xRUZqw), for general and integration questions.
-   Email: [support@truemarkets.co](mailto:support@truemarkets.co), for access, accounts and network setup.