# Approval hygiene: the monthly revoke that saves you

URL: https://www.caijing188.com/approval-hygiene/
Published: 2026-10-25T00:09:39+08:00 | Updated: 2026-10-27T22:09:52+08:00
Verified: 2026-10-27

## Quick answer
An ERC-20 approval outlives the site that requested it, and an unlimited allowance drains without a second signature. Revoking costs what a transaction costs: $2 to $10 on Ethereum L1 in FeeEdge's 17 August 2026 sample, and $0.001 to $0.002 on Base as of October 2026. Review monthly from a spending wallet.

## Summary
An approval is a standing permission written into the token contract, and the site that asked for it is not part of the arrangement afterwards. Unlimited allowances are the standard drain vector because one signature, with no expiry, is enough. A monthly review that revokes unnamed spenders, plus a separate spending wallet, caps what any single mistake can reach.

## Key takeaways
- An approval stays live after the site closes, changes hands or disappears
- Unlimited is an interface default, not a requirement
- Permit signatures leave no on-chain record until used, so a revoke sweep does not show them
- Revoking twenty approvals costs $2 to $10 each on Ethereum L1 and fractions of a cent on Base, per FeeEdge on 17 August 2026 and Ethereum.org in October 2026

## FAQ
Q: Does revoking an approval cost gas?
A: Yes, a revoke is an ordinary transaction. In FeeEdge's 17 August 2026 sample an ERC-20 transaction on Ethereum L1 cost $2 to $10, while Ethereum.org's October 2026 snapshot put Base at $0.001 to $0.002. Cleaning up approvals you granted on a cheap chain is nearly free.
Q: Can I revoke a permit signature?
A: Not directly. A permit is an off-chain signature that leaves no record until a spender uses it, so a revoke tool has nothing to show. The defence is to avoid signing permits you did not initiate, and to keep the wallet that signs them separate from savings.
Q: How often should approvals be reviewed?
A: Monthly is a workable rhythm, plus after any new site, mint or airdrop claim. Sort by allowance size, revoke anything unlimited you do not use, anything whose spender you cannot name, and anything attached to a site you have not visited this quarter.