Devcon2(Devcon2)

The Devcon2 Token (MainnetIndividualityTokenRoot) is an Ethereum smart contract deployed by Piper Merriam on November 16, 2016, to issue an ERC-20-compliant identity token to attendees of Ethereum's second developer conference (Devcon2), held in Shanghai in September 2016.

Each Ethereum address could hold at most one token, and each token was associated with an immutable string identity value. The contract included a hard minting cutoff at 8:00 AM Shanghai time on September 22, 2016 — after which no new tokens could ever be created, permanently fixing the total supply. Tokens were compiled with Solidity 0.3.6 and linked against a separate TokenLib library contract.

The contract was ERC-20 compliant but added constraints reflecting its non-fungible, one-per-person nature: transfer, transferFrom, and approve functions omitted the value parameter (always 1). Additional functions like ownerOf, tokenId, and isTokenOwner allowed querying token ownership. An upgrade mechanism enabled holders to migrate tokens to new addresses.

Piper Merriam published the full source code and a companion Token Explorer web app at devcon2-token.com, along with example code showing how to build survey and voting contracts on top of the token data. A community member later wrapped it with an ERC-721 interface, making it visible on OpenSea as a collectible.

The Devcon2 Token is one of the earliest on-chain implementations of the concept that became known as Proof of Attendance Protocol (POAP). While POAP did not formally launch until ETHDenver 2019, Merriam's 2016 experiment established the core pattern: issuing a non-transferable identity token to prove physical participation in an event.