1inch 1inch is a DEX aggregator that routes swaps across liquidity
1inch is a swap-finding service that compares decentralized trading pools and builds a route for exchanging one crypto token for a different digital asset. Its Pathfinder algorithm searches prices across decentralized exchanges, then may divide one order among several pools when that combination improves the quoted return after gas. The user keeps custody through a connected wallet, reviews the route, and authorizes execution on the chosen blockchain.
Bottom line: A split route earns its keep only when the added output exceeds its extra gas and pool-fee burden.
Should you use Classic, Fusion, or Fusion+?
The 1inch Swap API presents 3 execution modes for different settlement jobs: Classic for direct swaps, Fusion for same-chain intents, and Fusion+ for cross-chain intents.
Classic builds an on-chain transaction that your wallet broadcasts, so you pay gas in the network’s native asset and receive immediate execution or a revert. Fusion turns the exchange request into a signed order with a Dutch-auction price curve. Resolvers compete to fill it, cover the on-chain gas, and include that expense in their economics. Fusion+ links source-chain and destination-chain escrows, allowing a resolver to settle value across supported networks without a conventional bridge transfer or messaging protocol. The user signs an intent, while resolvers submit the required source-chain and destination-chain transactions.
Mode choice matters because each quote reaches settlement through different contracts, timing rules, and cost allocation.
Consider a wallet holding USDC on Base. A same-chain WETH purchase favors Classic when immediate submission and route control matter; Fusion fits when direct gas payment and transaction-ordering effects matter more. Moving that value to Arbitrum makes Fusion+ the relevant mode. None of the three removes market impact, so compare the destination amount, minimum return, and execution path before signing a Base-to-Arbitrum Fusion+ order.
The cost stack behind a quoted return
A 1inch quote combines pool pricing, price impact, routing gas, network gas, and any interface or integrator fee into one execution decision.
Across 1inch interfaces, infrastructure fees run from 0 to 5 basis points for stable pairs and from 0 to 30 basis points for non-stable pairs. One basis point equals 0.01%, making those upper bounds 0.05% and 0.30%. The Classic Swap API also accepts a partner fee from 0% to 3%. Those defined ranges sit beside the fee that the chosen pool charges, which follows that venue’s own rules rather than a universal aggregator rate.
Classic execution also spends native network gas, even when the route touches more than one liquidity source. Fusion shifts the direct gas payment to a resolver, although the auction price still reflects execution cost. The Classic API permits slippage settings from 0% through 50%, or a manually specified minimum return, but that broad technical range isn’t a recommendation. A useful quote balances output against pool depth, the trade’s price impact, and the gas consumed by a Classic route on Ethereum.
Which wallets and networks fit the route?
1inch works with self-custody wallets on supported networks, and the wallet must hold the source asset on the exact chain selected for execution.
Network identifiers prevent similarly named assets from becoming interchangeable. Ethereum uses chain ID 1, Optimism uses 10, BNB Chain uses 56, Gnosis uses 100, Polygon uses 137, Base uses 8453, Arbitrum uses 42161, and Avalanche uses 43114. Those numbers identify networks, not token balances. Solana uses chain ID 501 in the 1inch API, where intent-based and cross-chain flows cover swaps while Classic remains an EVM route.
Wallet compatibility includes MetaMask, Coinbase Wallet, Ledger through Ledger Live, Phantom for Solana, and connections using WalletConnect. Injected EVM wallets that implement EIP-6963 also appear in the interface. A wallet connection shares an address and signing capability; it doesn’t transfer custody or make a quote executable by itself.
Before confirming, match the network, source-token contract, and destination-token contract. Keep ETH for Classic gas on Ethereum, Base, Optimism, and Arbitrum.
Five stages from quote to settlement
A 1inch Classic swap moves through 5 visible stages: quote, allowance, route review, wallet confirmation, and on-chain settlement.
| Stage | Main failure mode |
|---|---|
| Quote | No executable route for the chosen pair and chain |
| Allowance | Router allowance remains below the input amount |
| Route review | The minimum received no longer suits the trade |
| Wallet confirmation | The wallet rejects the request or stays on another chain |
| Settlement | On-chain pricing moves beyond the minimum return |
An ERC-20 token requires the router to have sufficient allowance before Classic execution. With no existing allowance, the ordinary flow produces 2 on-chain transactions: 1 approval and 1 swap. A sufficient prior allowance reduces that sequence to 1 swap transaction. EIP-2612 permits and Uniswap Permit2 offer signature-based approval paths for compatible integrations, although token support and the chosen route determine whether either path applies.
The quote remains informational until the wallet signs. Once broadcast, validators process the transaction, the router calls the selected liquidity sources, and the minimum-return condition decides whether state changes settle. A revert leaves the exchange uncompleted while consuming the gas used by the attempted Ethereum call.
How does Pathfinder split a swap?
Pathfinder compares candidate paths, divides a 1inch order across pools when useful, and merges compatible route legs to improve the net quoted return.
Pathfinder v6.1 evaluates direct pools, connector-token paths, and different market depths inside one protocol. Familiar liquidity sources include Uniswap, Curve, Balancer, SushiSwap, and PancakeSwap on networks where their contracts and pools operate. Wrapped Ether, or WETH, also serves as a connector because its ERC-20 behavior fits token-to-token paths more directly than native ETH.
A USDC-to-WETH request might have a strong direct pool, yet another path through DAI could offer better pricing for part of the order. Pathfinder compares the combined destination amount with the extra gas from additional calls. It then constructs calldata for the aggregation router, which executes the selected proportions as one user-authorized transaction rather than asking the wallet to sign each pool interaction.
More splits don’t automatically improve execution. Every extra leg adds contract calls and gas, while shallow reserves increase price impact. The winning route therefore reflects both liquidity and computation, with the actual pool exchange occurring on Curve or Uniswap.
Where aggregation earns its place
Crucially, 1inch aggregation earns its place when liquidity fragments across venues, a direct pool lacks enough depth, or a connector token opens a stronger path. It serves same-chain token conversion, price-sensitive larger swaps, stablecoin routing, and cross-chain intent settlement. Small, liquid trades still deserve a quote comparison because a longer route may spend more gas than it saves. The clearest benefit appears when one order draws efficiently from named sources such as Curve and Uniswap, as documented in 1inch rewards.
Trade-offs, 1INCH, and named alternatives
The main 1inch trade-offs are route complexity, allowance scope, changing quotes, and the extra settlement assumptions introduced by resolver-based modes.
A multi-source route touches more contracts than a single-pool exchange, widening the set of contract behaviors involved. Classic gas remains spent when execution reverts. A quote also ages as reserves change, while its minimum return creates the hard boundary for settlement. Token approvals persist independently of the quote; an unlimited allowance stays active until the wallet lowers or revokes it. Fusion and Fusion+ replace immediate broadcast with signed orders, resolver competition, auction timing, and, for cross-chain execution, linked escrows. Cross-chain settlement also relies on timelocks and secret-linked escrows to complete or unwind the exchange. The matching explanation appears in 1inch overview.
The 1INCH token launched with a total issuance of 1.5 billion units. The ERC-20 token supports governance and utility within the ecosystem, but holding it isn’t required for an ordinary swap. Gas payment follows the selected chain and execution mode rather than the 1INCH balance.
Named alternatives make the decision boundary clearer. Uniswap offers direct interaction with its own pools and concentrated-liquidity positions. CoW Swap uses signed intents and batch-auction settlement on supported EVM networks. Matcha aggregates liquidity through 0x infrastructure, while Jupiter focuses on Solana-native routing. Choose by chain coverage, custody model, order type, and the final quoted return; a Solana-first route points naturally toward Jupiter.
1inch - common questions
Does 1inch hold my tokens during a Classic swap?
1inch doesn’t take custody of tokens during a Classic swap. Your wallet authorizes an allowance, then signs a transaction calling the aggregation router and selected liquidity sources. Assets move through that confirmed on-chain transaction, while the interface prepares route data. Until you approve and sign, the quote alone can’t move funds. A failed transaction leaves the swap uncompleted, although network gas remains spent.
What happens if a Fusion order expires without a fill?
An unfilled Fusion order reaches its expiry without executing the intended exchange. Because the user signs an off-chain intent and a resolver supplies the settlement transaction, the user doesn’t spend network gas merely to place the order. Any token allowance associated with the order remains a separate on-chain permission until its amount changes or it is revoked. The sensible next action is to request a fresh quote, because liquidity, gas, and the auction curve have moved.
What is the difference between price impact and slippage on 1inch?
Price impact describes how the trade moves through pool liquidity, while slippage tolerance sets the execution boundary relative to the quote. A larger order against shallow reserves creates more price impact before confirmation. Reserve changes after the quote create slippage risk. In Classic mode, the minimum return enforces the boundary; if execution would deliver less, the transaction reverts rather than settling below that amount.
How long does a 1inch quote remain usable?
A 1inch quote is a point-in-time route rather than a fixed-duration price promise. Pool reserves, token prices, and network gas change continuously, so the usable window ends when on-chain simulation or the minimum-return condition no longer passes. Reopening the confirmation screen requests updated route data. For Classic execution, slow wallet confirmation raises the chance that the prepared call reverts; Fusion handles timing through its auction and order-expiry parameters instead, rather than waiting on a prebuilt transaction alone.
Which token standards does 1inch handle?
1inch handles ERC-20 tokens on supported Ethereum Virtual Machine networks and SPL tokens through its Solana intent flow. Native assets such as ETH and SOL also receive handling, with wrapping or resolver logic applied where required. Compatibility belongs to the specific mode and chain: Classic and intent support aren’t identical, and a listed token needs liquidity before an executable quote exists for that pair.
Does 1inch support limit orders alongside swaps?
1inch includes limit-order functionality alongside immediate and intent-based swaps. A limit order expresses a token exchange at specified terms and waits for a counterparty or resolver to fill it, so execution isn’t assured merely because the order exists. The wallet signs the order data, and any required token allowance remains relevant. This suits a target-price instruction, while Classic mode suits a swap that should submit to the chain immediately under current liquidity and resolver availability.
When a Classic swap reverts, which costs remain?
A reverted Classic transaction consumes gas used by its attempted execution. Validators process the call even when state changes roll back, so that fee isn’t refunded. Source tokens remain with the wallet because the exchange didn’t settle, while an earlier approval remains separate. Before trying again, refresh the quote, check minimum received, confirm the chain, and ensure the wallet has enough native gas.