Unit 2 · Level 1 · Reading transactions
Approvals in the wild
The Crypto course warned you about signing blindly. Now you will see what those signatures look like from the outside. An 'approve' transaction gives a contract permission to move your tokens. On an explorer you can see exactly who you approved, for how much… and many approvals are for an effectively unlimited amount. Wallet drainers feast on forgotten approvals.
Free to play. No ads, no token, no account needed to start.
What you get asked
An approval's amount shows as 115792089…, an absurdly long number. What does that mean?
That's the maximum number the system can store, the convention for 'unlimited'. The contract can spend everything you hold, now or years from now.
Why do dapps ask for unlimited approvals instead of exact amounts?
It saves users a gas fee per trade, which is convenient. But convenience for you is also convenience for an attacker if that contract is ever compromised.
If a contract you approved turns malicious, it can drain that token until you ___ the approval.
Approvals don't expire on their own. Revoking is a small on-chain transaction that sets the allowance back to zero: cheap insurance.
Put the approval-hygiene routine in order
Ten minutes, a few cents of gas. Do this after every airdrop season or dapp experiment. Old approvals are the quietest risk in your wallet.
The Crypto course said 'never sign blindly.' What does reading the chain add to that advice?
The chain remembers what you signed even when you don't. Explorers and approval tools turn 'I hope I'm safe' into 'I checked, and now I am.' 🐜
The rest of this unit
Transfers, approvals, swaps, mints: learn what each really looks like.