Technical reference
ERC-1967: finding the implementation behind a proxy address
The address users recognise can remain unchanged while the code they execute changes.
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Three important storage locations
ERC-1967 specifies storage locations for implementation, beacon and administrator information used by compatible proxies. These slots help tools discover delegated code without relying solely on a frontend label. A beacon-based proxy obtains its implementation through the beacon, adding another contract to inspect.
Snapshot the code that actually ran
A finding should record the chain, proxy address, block and implementation active at that block. Reviewing today's implementation against yesterday's transaction can produce a false explanation. Upgrade-related events are useful leads, but the corresponding state and executed call path matter too.
Authority is a separate investigation
Knowing the implementation does not identify every person able to replace it. Follow ownership, access-control roles, timelocks and any upgrade mechanism in the relevant contracts. The proxy standard gives a storage convention, not a guarantee of decentralised administration or an audit of the implementation. An unchanged token address is therefore not proof of unchanged behaviour.