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Before a swap can pull a user’s source token, the user authorizes a spender. You can do that with an on-chain approve, or by signing a permit so there’s no separate approval transaction. Which spender you authorize depends on the execution mode; the choice between approve and permit is the same either way.

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Which spender to authorize

The spender is always the contract that settles the trade, never a separate proxy:
  • Delta (Swaps, Limit Orders, TWAP): the Delta contract. Every Delta quote returns it as delta.spender, so you can read it straight from the quote response.
  • Market: the Augustus v6.2 router. The user approves Augustus v6.2 directly.
Each is deployed at the same address on every chain that supports it. See Chains & contracts for the addresses and per-mode availability.

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Approve or sign a permit

Both methods work for Delta and for Market:
  • On-chain approval: a standard ERC-20 approve(spender, amount). One transaction, once per token.
  • Permit: sign an EIP-2612 permit or a Permit2 message naming the spender, and pass it in the build call instead of approving on-chain. Delta takes it as the permit field on POST /v2/delta/orders/build; Market takes it as the permit field on POST /transactions/{chainId}. Both the Delta contract and Augustus v6.2 accept either an EIP-2612 or a Permit2 payload.
A permit skips the separate approval transaction, which is the reason to use it.

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Native ETH

Native ETH is never approved. For a Market swap, the native value is sent with the transaction. For Delta, the ETH is represented as dETH, which the Delta contract can move without an approval; see Native ETH (dETH).

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Limit Orders and TWAP use on-chain approval

A permit is bound to a single-use token nonce and a deadline, so it only fits an order that settles right away, like a market Delta swap or a Market swap. A limit order rests until its price is met, and a TWAP settles across slices over time. By the time either settles, the permit’s nonce is spent or its deadline has passed. For both, approve the spender on-chain for the total amount instead of signing a permit.
Last modified on June 11, 2026