Slippage vs a signed limit price
Both models enforce a minimum output. The differences are how orders are submitted, who chooses the route, and how execution and failure costs are handled.
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The short version: router minimum-output bounds and signed limits both enforce the minimum you authorize. Ophis adds offchain order submission, solver routing and uniform batch prices per token pair. The solver's settlement can still be public; the slippage band is not a guarantee of execution at the reference quote.
What is slippage in crypto trading?
Slippage is the difference between the price you were quoted and the price you actually get. It exists because time passes between quoting and execution: other trades land first, pools move, and your transaction executes against whatever state it finds. A slippage tolerance is the worst version of that outcome you agree to accept in advance.
Why do router DEXes need a slippage tolerance?
Because a router swap fixes its route at signing time and executes later on-chain. If the pool has moved by more than the tolerance when the transaction lands, the swap reverts and you pay gas for nothing, so the tolerance exists to keep trades from failing constantly. The price of that convenience is pre-authorizing a worse fill every single time.
What does a slippage tolerance actually cost?
It is a standing offer to accept up to that much less, and in adversarial conditions the offer gets taken: a sandwich attacker can harvest up to the full tolerance, and ordinary price movement inside the tolerance is simply yours to absorb. Set it tight and trades revert; set it loose and you fund the attack. That dilemma is built into the tolerance model itself.
How is a signed limit price different?
Both a router minimum-output bound and an Ophis signed limit are contract-enforced. Ophis converts your quote and slippage setting into a signed order limit, then lets solvers find a route within it. Standard ERC-20 orders are submitted offchain and clear in batches; router swaps authorize a transaction path. Execution inside either permitted price band can still be worse than the original quote.
What happens when the price moves in my favor?
Execution beyond your signed limit is surplus. Under the standard policy, Ophis retains 80% of reference-quote improvement on volatile pairs (99 bps cap) or 50% on stable pairs (20 bps cap), and the trader receives the remainder. CoW-hosted chains additionally apply CoW Protocol's upstream fees. In tolerance systems, movement in your favor within the band may simply never reach you.
Do hard-limit orders fail more often?
They fail differently, and cheaper. A router swap that violates its tolerance reverts on-chain and burns gas. An ERC-20 order that cannot be filled at its limit just stays open until it expires and lapses with nothing spent; you signed a message, not a transaction. You either trade at your floor or better, or you do not trade.
Go deeper
How the tolerance gets harvested in practice: what is a sandwich attack. What happens to execution above your floor: what is surplus. The mechanism that enforces the floor: what is an intent-based DEX aggregator.