Web 3.0 DApps & Smart Contract for Pentest & Bug Bounty 2025

Understand blockchain as a distributed, immutable ledger governed by a decentralized network of nodes, enabling cryptocurrencies and smart contracts on web3 platforms.

Explore the core components of a blockchain—decentralized networks (permissioned and permissionless), cryptography, immutable ledgers, consensus, and smart contracts that read and write data across client, backend, and blockchain interface.

Explore how blockchain preserves data integrity through hashing, nonce-based proof of work, and chain linking, including tamper resistance and 51% attack protection.

Explore how Ethereum's blockchain, nodes, miners, gas, and immutable smart contracts enable decentralized applications by running a virtual machine that executes code and stores results on the blockchain.

Learn how smart contracts run on the blockchain, written in solidity, rust, go, or python, and executed by the EVM on Ethereum, with addresses, gas fees, and wallets like Metamask.

Explore metamask as a web3 wallet for connecting apps and storing ether, tokens, and NFTs. Install the Firefox extension, create a wallet, and safeguard the 12-word recovery phrase.

Explore how decentralized applications use smart contracts on decentralized networks, learn about dApps and DAOs, and examine AMMs and exchanges like Uniswap and Sushiswap.

Learn how a dApp uses a wallet like MetaMask to send ether to an externally owned address, connect accounts, switch to a test network, and sign transactions.

Explore Remix IDE in the browser, compile and deploy Solidity contracts like Storage.sol using the Solidity compiler, and test interactions in the JavaScript VM with store and retrieve functions.

Explore solidity fundamentals, including contract syntax and data types, to detect vulnerabilities in smart contracts. Practice with Remix IDE to understand the address datatype and declarations like int, uint, bool.

Explore Solidity data types in Remix IDE, including uint, int, bool, and address, with size variations and visibility modifiers (public, private, internal, external) using a 0.6.0 compiler.

Explore the three types of Solidity variables—local, state, and global—and learn which are stored on the blockchain, plus global vars like msg.sender, msg.value, msg.data, and block.timestamp.

Distinguish state and local variables, apply visibility modifiers, and use global vars like msg.sender to return the caller's address in a deployed Solidity contract.

Learn how to read and write to a blockchain using smart contract functions. Reading is free via view functions, while writing costs gas and transactions to update state.

Solidity functions provide reusable code you can call anywhere, avoiding repetition. Define a function with name, arguments, scope, and a return value, illustrated by add numbers example in Remix IDE.

Deploy a simple addNumbers function in Remix, taking two uints A and B and returning A+B as C; no output without view or pure, so learn about these keywords.

Explore Solidity variable types, including state, local, and global variables, and learn how a public function returns multiple values, updates a state variable, and uses msg.sender for global context.

Explore Solidity view and pure functions: return public uint state variable num via a view function, and convert to pure when not reading or changing state; note the auto getter.

Constructors in Solidity run only once during contract creation to initialize the contract, such as setting an owner or initial state via arguments like _num.

Learn how to use constructors in Remix to initialize contract state by setting num1 to six and owner to the deployer (msg.sender) during deployment.

Explore solidity function modifiers, including an only owner access control modifier and re-entrancy guard; see how the underscore replaces function code and how required enforces and reverts.

Learn how to implement solidity modifiers to enforce access control with only owner, using require and msg.sender to guard functions like changeNumber in a MyContract.

Explore Solidity mappings as key-value data structures, retrieve values by address keys, and understand nested mappings with public visibility and practical examples.

Learn to interact with one smart contract from another using Remix by deploying contracts, creating contract instances, and invoking functions such as changeNum to update public state.