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

This is the competitive intelligence layer.

Instead of maintaining one centralized routing algorithm, allow multiple independent solvers to submit solutions.

A solver should evaluate:

Route profitability = expected user surplus − gas − liquidity cost − protocol fee − execution risk

For example, a solver could determine that:

• 40% of a $500,000 USDC order should execute through Uniswap
• 35% through Curve
• 15% through private inventory
• 10% through an RFQ market maker

Another solver may provide a better price using a private inventory position.

The auction mechanism chooses the winning solution based on the protocol's settlement rules.

CoW's fair combinatorial auctions are particularly relevant because solvers can bid on individual orders or groups of orders, enabling batch-level optimization rather than isolated trade routing.

4. Filler Network

Fillers should be treated as professional execution providers rather than simply RPC-connected wallets.

A filler infrastructure can include: