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Solidity Smart Contracts: Tokens and Marketplace

School - ESGI M1 SI & Bachelor 3 Solo 2024 - 2025 Completed

A set of Solidity smart contracts written and tested with Foundry across two courses of the curriculum, covering token issuance, an on-chain marketplace, and weighted governance voting. Each contract was compiled, deployed to a local chain and exercised through Foundry's test suite (forge test).

Interaction flow between the contracts User wallet EOA ERC20 Token mint / transfer Marketplace item listing, purchase, coin flip Voting weighted by token balance
A user's wallet mints/holds ERC20 tokens, spent either in the on-chain marketplace or as voting weight in the governance contract.

Context

Two separate courses contributed contracts to this body of work: blockchain security in the M1 curriculum (March 2025) and a blockchain module in Bachelor 3. Both used Solidity with the Foundry toolchain (forge, tests, scripts) rather than Remix, to practice a real compile/test/deploy workflow.

What was built

  • A custom ERC20 token with an owner/admin system and paid minting (1 ETH mints a fixed token amount), including custom error handling (HILALO.sol).
  • An on-chain marketplace contract: item listing/creation and purchase paid in the ERC20 token, plus a small coin-flip mini-game (Marketplace.sol).
  • A weighted voting contract from the Bachelor 3 coursework: voting power proportional to token holdings, with Voter/Proposal structures (voting.sol).
  • Additional ERC20 variants built on OpenZeppelin's implementation for comparison (owner-restricted mint vs. no access control).
  • Unit tests written and run through Foundry's forge test.

Tech stack

Solidity 0.8.20 Foundry OpenZeppelin ERC20 forge test

Status

All contracts completed, tested and submitted across both courses.

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