One-Time Approval

What is One-Time Approval

Since Matcha Meta was developed by the team at 0x, a leading DEX Aggregator, many users have already trusted the 0x smart contracts with billions of dollars in approvals.

Matcha Meta allows users to reuse their approvals on 0x's smart contracts and trade on any aggregator.

Security Benefits of One-Time Approval

One-Time Approval is designed to reduce approval risk and limit trust exposure:

• Single trusted approval surface Instead of approving tokens to multiple aggregator contracts, users approve a single 0x contract (AllowanceHolder) that routes trades across aggregators.

• Reduced smart contract trust exposure Without One-Time Approval, users must grant approvals directly to each aggregator they trade through, requiring trust in each aggregator’s smart contracts individually.

• Audited and widely reviewed infrastructure The AllowanceHolder contract has undergone multiple external audits and security reviews: https://github.com/0xProject/0x-settler/tree/master/audits

• Battle-tested at scale and widely trusted by users

  • 0x smart contract infrastructure has processed over $55B+ in trading volume.

  • Over 800,000 wallets have active approvals on Ethereum

  • Over 965,000 wallets have active approvals on Base

By consolidating approvals into a single, extensively reviewed contract, One-Time Approval helps reduce the number of contracts that can access your tokens.

Whack-a-mole Approvals

On many aggregators, token approvals must be granted individually to each aggregator contract.

For example:

• Odos might have the best quote → you approve Odos

• Quotes refresh → 1inch becomes best → you must approve 1inch

• Quotes refresh again → another aggregator becomes best → repeat

This is a common experience on other Meta Aggregators. By allowing users to reuse their approvals on 0x's smart contracts (assuming you were willing to trade on 0x anyway), Matcha Meta eliminates this problem with One-Time Approvals.