Encyclopedia DeFi · Entry 56
Swap routing and aggregators: selecting a path through liquidity
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Multiple hops | A route can exchange A for an intermediate token before B. | [1] |
| Split execution | Routing can divide an input across several pools. | [1] |
| Permission | The spender authorized for routing is a specific contract. | [3] |
Think of pools as possible paths
A direct A-to-B pool is one path. An A-to-C pool followed by C-to-B is another. Splitting the input can also reduce how far any one pool moves along its curve, at the cost of more contract work.
Uniswap’s September 2021 Auto Router announcement is a dated example: it describes split routing and considering gas when choosing a path. It does not establish which routes, venues or cost estimates any current aggregator uses.
Compare like-for-like output
Imagine route one delivers 1,000 quote-token units with an execution cost valued at 2 of those units. Route two delivers 1,003 but costs 7. The illustrative net amounts are 998 and 996 respectively, before any extra interface charges or uncertainty.
This comparison depends on valuing the gas asset in the same unit and at the same time. A longer path can win for a large swap and lose for a small one. An off-chain route search is an estimate until the encoded transaction executes.
Inspect the transaction behind the quote
The route, permitted spender, recipient, input and final minimum output are concrete parts of the request. An attractive displayed price does not justify an unrelated approval or a different recipient.
An aggregator searches its supported venues and assumptions; it cannot prove that no better executable trade exists anywhere. Quotes may expire as state changes, and a route can fail if any required operation or final bound fails.
Direct answers
Questions people ask
Does an aggregator always choose the best trade?
It can compare the venues and routes it supports using its own cost estimates. That is not a guarantee of the best executable result across all markets or future states.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
A swap router executes a path through one or more pools. An aggregator compares available paths or liquidity sources and may split a trade. The most useful comparison includes fees and execution costs; a route with the largest gross token output can still have a lower net result.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimMultiple hops: A route can exchange A for an intermediate token before B.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimSplit execution: Routing can divide an input across several pools.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimPermission: The spender authorized for routing is a specific contract.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimRevision history
- — First publication after primary-source research and independent automated verification.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- Introducing the Auto RouterUniswap Labs
A dated implementation example of routing across pools with gas-aware optimization.
Locator: Split Routes; Gas Cost Awareness · Version / scope: 2021-09-16 announcement · Retrieved: 2026-10-02Open source - Uniswap v2 pricingUniswap
Reserve-dependent quotes, trade bounds and external price observations.
Locator: Pricing Trades; Exact Input; Exact Output · Version / scope: Uniswap v2 · Retrieved: 2026-10-02Open source - ERC-20: Token StandardEthereum Improvement Proposals
The token spending allowance is separate from a website connection.
Locator: Methods: approve, allowance, transferFrom · Version / scope: ERC-20 final · Retrieved: 2026-10-02Open source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees of Satoshi editorial project. “Swap routing and aggregators: selecting a path through liquidity.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/swap-routing-and-aggregators/