Back to: L2 Developer Path
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Objective: prove a deployed contract matches its advertised code — the single most useful 5-minute check in DeFi.
“Verified” on Etherscan means the published source compiles to the on-chain bytecode. Unverified = unreadable logic = walk away with size.
Concept: what verification proves (and doesn't)
It proves *this source* produces *that bytecode* — nothing about whether the source is safe, honest, or final (proxies can swap logic later). Verification is necessary, never sufficient.
Hands-on lab (testnet, free)
- Take your lesson-6 contract address; check its explorer page — unverified initially.
- Verify it (flatten or standard-json input via the explorer UI).
- Read a function on-chain: call
retrieve()through the explorer’s contract tab. - Now inspect a *proxy*: find an implementation address slot and note how the logic could change without the address changing.
Safety checklist
- Interact only with verified contracts when money is involved.
- For proxies, audit the *implementation*, not the friendly front address.
- Check the contract’s age and transaction history — fresh + huge inflows = investigate first.
Related glossary
Next lesson: gas optimization 101.