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

# Orderly Orderbook Design

> Learn how Orderly's central limit order book combines CEX-level performance with on-chain settlement.

Orderly is an omnichain decentralized orderbook protocol. It provides the matching engine, liquidity, and infrastructure for builders (DEXes) to offer perpetual futures trading without building it themselves.

## Orderbook design

Orderly uses a **central limit order book (CLOB)** -- the same type of system used
by major centralized exchanges. Orders are submitted and matched off-chain,
while matched trade data is uploaded for on-chain settlement.

* **Transparency:** The public orderbook shows aggregate prices and quantities.
  Matched trade data becomes publicly observable after it is included on
  Orderly L2.
* **Authentication:** Order requests are signed using a Trading Key, and the
  request signature is verified before matching.
* **Speed:** A high-performance off-chain matching engine provides low-latency execution.

## Omnichain approach

Unlike most DEXes that run separate order books per chain, Orderly brings all orders from all supported chains into a **single shared order book**. This unifies liquidity across chains.

The system has three layers:

**Asset Layer (Asset Vaults)** -- on each supported chain

* Where your funds reside. You interact with this layer when registering, depositing, and withdrawing.

**Settlement Layer (Orderly L2)** -- on a single chain

* A ledger that records settlement data on Orderly L2. Matched trade data
  becomes publicly observable after L2 inclusion. Users do not interact with
  this layer directly.

**Engine Layer (Orderbook)** -- order-related services

* Where trade execution happens. Includes the matching engine, risk engine, and other services. You interact with this layer when managing orders.

After orders are matched, matched trade data is batched and uploaded to Orderly
L2 (built with OP Stack). Each L2 batch or block publishes the corresponding
batch data to Ethereum as calldata or blob data, where it can be observed and
decoded. Cross-layer communication (deposits, withdrawals, balance updates) is
powered by LayerZero.

## Order and settlement visibility

Order submission, matching, and settlement have different visibility boundaries.

### Order submission

A client or broker sends the full order request to Orderly's off-chain
infrastructure. Orderly's operator and matching infrastructure can read the full
order content. The public resting orderbook displays only aggregate prices and
quantities, without account or individual order details. The order request is
not submitted to a public blockchain mempool before matching.

### Matching

The matching engine processes full order details off-chain using price-time
priority. Matching does not depend on ordering a user transaction in a public
blockchain mempool. This does not mean the order is hidden from Orderly's
operator or matching infrastructure.

### Batch upload

Only matched trade data is included in the settlement batch. Unmatched and
canceled orders are not included. The batch is created after matching, and its
matched trade data becomes publicly observable after inclusion on Orderly L2.
The pre-match public-mempool guarantee does not extend to this post-match stage.

### On-chain settlement

Each Orderly L2 batch or block is published to Ethereum as calldata or blob data
that public observers can inspect and decode once the L1 publication is
available. This visibility occurs after matching and L2 inclusion. No guarantee
is made that post-match settlement data remains private.

## MEV protection

For this order flow, MEV protection specifically refers to public-mempool
front-running before matching. Because order submission and matching happen
off-chain, a public blockchain observer cannot inspect an order-submission
transaction in a public mempool and place a blockchain transaction ahead of it.

This guarantee is limited to that pre-match public-mempool scenario. Orderly's
operator and matching infrastructure can see full order details before matching,
and matching follows price-time priority. After matching, settlement data becomes
publicly observable as described above. Off-chain matching should therefore not
be interpreted as making post-match settlement data private or as eliminating
every form of MEV.