How to Build an Intent-Based DEX Aggregator With Solver and Filler Networks

DEX aggregation is moving beyond conventional smart-order routing. Instead of asking users to approve a token, select a route, pay gas, and execute a swap themselves, newer trading architectures let users sign an intent describing the outcome they want while external solvers and fillers compete to execute it.

This shift is visible in protocols such as CoW Protocol and UniswapX, where execution is separated from the user's transaction flow. UniswapX, for example, uses signed orders and competitive fillers to source liquidity from AMMs and private inventory, while CoW Protocol uses batch auctions and solver competition to find execution paths.

For businesses evaluating a DEX Aggregator Development Company, this creates a fundamentally different architecture: the aggregator is no longer simply a routing engine. It becomes an intent auction, solver coordination, liquidity discovery, settlement, and MEV-management system.

What Is an Intent-Based DEX Aggregator?

A conventional DEX aggregator calculates a route such as:

USDC → Uniswap V3 → ETH

The user receives a transaction containing that route and submits it on-chain.

An intent-based aggregator changes the model to:

“Sell 10,000 USDC and receive at least 5.1 ETH before the deadline.”

The user signs the desired outcome rather than specifying how the swap should happen.

The protocol then distributes that intent to competing solvers or fillers. They determine whether the order should be executed against an AMM, another DEX, private inventory, an RFQ market maker, or even another user's opposing order.

CoW Protocol describes this as a two-stage optimization problem: solvers first determine optimal routing and then optimize their bid for the auction.

This distinction is critical when designing a modern DEX Aggregator Development Company solution. The core product is no longer “find the cheapest DEX route.” It is find and settle the best executable outcome.

Why Solver and Filler Networks Matter

The most important architectural change is separating order creation from order fulfillment.

A solver can examine:

• DEX liquidity
• Aggregator APIs
• RFQ liquidity
• Private market-maker inventory
• Cross-chain liquidity
• Coincidence-of-Wants opportunities
• Gas costs
• Slippage
• MEV exposure
• Settlement constraints

The solver then submits a proposed execution.

Fillers perform a closely related but execution-focused role. In UniswapX, fillers compete to satisfy signed orders using their own strategies and can use on-chain liquidity or private inventory.

For a DEX Aggregator Development Company, supporting both models creates a broader liquidity marketplace instead of depending on a single routing algorithm.

Core Architecture of an Intent-Based DEX Aggregator

A practical architecture should contain six major layers.

1. Intent Layer