All lessons
DEX approvals: inspect before you sign
A swap amount of 20 does not mean the requested permission is only 20.
Read a token allowance and explain what revocation can and cannot do.
An ERC-20 allowance can authorise a spender to move tokens from an owner's account within its rules. The spender is a contract address, not merely the friendly website name. An allowance is separate from the intended swap amount.
Check network, token address, spender, amount and transaction or signature type. Unlimited approval can expose later incoming balances to that spender as well. Some signatures grant permissions without an immediate on-chain transaction, so no gas prompt does not imply harmlessness.
Disconnecting a website commonly removes a wallet connection; it does not by itself cancel an existing on-chain token allowance. Revocation changes a particular permission under its mechanism and may require a network transaction and cost.
Revocation cannot recover stolen tokens, repair an exposed seed phrase or cancel every kind of signature automatically. A compromised wallet needs a separate security response. Use official tools reached independently and inspect requests; fake revoke sites can request new harmful permissions.
Let’s work through it
- Reach the genuine site independently and identify the network.
- Inspect token, spender, allowance and signature meaning.
- Review existing permissions using trusted documentation and record what changed.
Let’s use numbers · hypothetical example
A fictional wallet holds 100 T and plans to swap 20 T. A standard allowance of 20 T limits that spender's token allowance to 20 at that time, whereas an unlimited allowance is not limited to the intended swap. Other permissions, token rules and account compromise can create separate risks.
Easy mistakes to watch for
- Approving by website name without checking the spender.
- Assuming disconnect cancels existing allowances.
- Thinking revocation repairs a leaked recovery phrase.
Keep in mind
This lesson is a paper checklist. Never type a recovery phrase into a checker, support chat or revoke website.
Your turn
On a mock transaction screen, label the five checks and distinguish swap quantity from allowance. Do not connect a real wallet or sign anything.
A quick check before we move on
What does disconnecting the website prove about an existing allowance?
- All token permissions are cancelled
- The recovery phrase becomes safe again
- It does not by itself prove the allowance was revoked
Check answer
It does not by itself prove the allowance was revoked A connection and an on-chain allowance are different; permission status must be checked through the relevant mechanism.
Sources and further reading
Content reviewed: 29 October 2026
Educational material with hypothetical examples. Trading can cause substantial losses. A course, pattern, stop order or past result cannot guarantee a profit or limit every loss. Practise in simulation and check current rules and product terms in your jurisdiction.