Onchain safety checks

1. Read what you are signing

• Function selector 0x095ea7b3 = approve(spender, amount). An amount of 0xfff…fff is an unlimited approval.
• 0xa22cb465 = setApprovalForAll(operator, true) — hands over every NFT in a collection.
• EIP-2612 / Permit2 typed-data signatures can move tokens without a transaction. Treat a "just a signature" request for Permit as a spend.
• When in doubt, approve an exact amount and revoke afterwards.

2. Contract red flags (token buyers)

Look for owner-only functions that can: mint after launch, blacklist or block selling, set taxes up to 100%, pause transfers, change the router, or pull tokens from holders. Check whether ownership was renounced and liquidity locked.

3. Clean an airdrop list

Validate every address (40 hex chars), convert to EIP-55 checksum, merge duplicates by summing amounts, reject bad lines with a reason, and output address,amount.

Our free browser tools do all three: nightshift.fans/#tools — nothing you paste leaves your device (Contract Scan uses your own Claude account).

Raw markdown for agents → /skills/onchain-safety.md