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The Ethereum Codex

The World's Programmable
Blockchain.

16 modules. One real project. Every command narrated. Every error explained. Master Solidity, ERC tokens, DeFi patterns, and EVM internals — and leave with a portfolio project and the lore.

16 Modules
~6 Hours
40+ Error Recoveries
1 Real Project
Start Free Trial → View Curriculum ↓
Why Ethereum

Why practitioners choose Ethereum

Ξ
The largest ecosystem

More developers, more tooling, more deployed contracts than any other chain. Mastering Ethereum opens doors to the entire EVM-compatible ecosystem — Polygon, Arbitrum, Optimism, Base, and beyond.

⊛
Solidity: the lingua franca

Solidity is the most widely used smart contract language. Learn it once, deploy on dozens of EVM-compatible chains. The lore transfers.

★
DeFi was born here

Uniswap, Aave, Compound, MakerDAO — every DeFi primitive was invented on Ethereum. Understanding these patterns is essential lore for any blockchain practitioner.

⬢
EIP-7702 and account abstraction

The Prague upgrade brings native account abstraction to Ethereum. The Codex covers this and every other post-merge innovation, always current.

Curriculum

Every module builds toward one real product

You don't do isolated exercises. From Module 00 to Module 15, you build a complete DeFi application on Ethereum. By the end, you'll have a production-ready project and the lore to back it up.

00
Environment Setup + Quick Win
Get your Ethereum development environment running and deploy your first contract in minutes.
15 min

What You'll Learn

  • Hardhat/Foundry setup
  • Local node configuration
  • Your first deployment

What You'll Do

  • Install toolchain
  • Deploy a contract to local node
01
Consensus: How Finality Works
Gasper, Casper FFG, LMD-GHOST. How Ethereum achieves finality after the Merge.
theoryconsensusPoSFREE
30 min

What You'll Learn

  • Proof of Stake and the Merge
  • Gasper consensus mechanism
  • Finality vs probabilistic confirmation

What You'll Do

  • Build mental model of PoS
  • Compare to PoW and PBFT
02
Run Your Local Node
Geth or Anvil in development mode. Watch blocks being produced. Query eth_getBlockByNumber.
25 min

What You'll Learn

  • Execution vs consensus clients
  • JSON-RPC API

What You'll Do

  • Run local development node
  • Query block data
  • BREAK IT — misconfigured client
03
Accounts and Wallets
EOAs vs contract accounts, ECDSA keypairs, nonce management.
28 min

What You'll Learn

  • EOA vs contract accounts
  • ECDSA key generation
  • Nonce management

What You'll Do

  • Generate wallets
  • Fund from faucet
  • BREAK IT — nonce gap error
04
Account State and Balances
State trie, storage trie, balance tracking, and the world state.
33 min

What You'll Learn

  • Merkle Patricia trie
  • Account state structure
  • Storage layout

What You'll Do

  • Query account state
  • Inspect storage slots
05
Transactions: Full Lifecycle
EIP-1559, gas estimation, signing, and submission. Every receipt field explained.
28 min

What You'll Learn

  • EIP-1559 fee model
  • Transaction types (0, 1, 2)
  • Receipt and log decoding

What You'll Do

  • Send ETH transfer
  • BREAK IT — gas estimation failure
06
Smart Contracts: Solidity
Your first Solidity contract. Compile, deploy, interact. ABI encoding and function selectors.
28 min

What You'll Learn

  • Solidity fundamentals
  • ABI encoding
  • Function selectors

What You'll Do

  • Write and deploy a contract
  • Call functions via ethers.js
  • BREAK IT — revert with custom error
07
ERC-20: Fungible Tokens
The token standard that powers DeFi. Mint, transfer, approve, and allowance patterns.
33 min

What You'll Learn

  • ERC-20 interface
  • Approve/transferFrom pattern
  • Common pitfalls (infinite approve)

What You'll Do

  • Deploy ERC-20 token
  • Implement approval flow
  • BREAK IT — insufficient allowance
08
ERC-721: Non-Fungible Tokens
NFT standard. Minting, metadata, and the ownership model.
30 min

What You'll Learn

  • ERC-721 interface and extensions
  • Metadata and tokenURI
  • Enumerable and burnable patterns

What You'll Do

  • Deploy NFT collection
  • Mint and transfer
09
Events and Logs
Indexed events, log topics, bloom filters, and building event-driven architectures.
25 min

What You'll Learn

  • Event emission and indexing
  • Log topics and bloom filters
  • Event-driven architecture

What You'll Do

  • Emit and query events
  • Build event listener
10
DeFi Patterns: AMM & Swaps
Constant-product formula, liquidity pools, and the Uniswap V2 pattern.
29 min

What You'll Learn

  • x * y = k formula
  • Liquidity provision and impermanent loss
  • Swap routing

What You'll Do

  • Build simple AMM contract
  • Add liquidity and swap
11
Time-Locks and Escrow
Time-based and condition-based escrows. Vesting contracts and timelocks.
28 min

What You'll Learn

  • Timelock patterns
  • Escrow contract design
  • Vesting schedules

What You'll Do

  • Deploy timelock escrow
  • Fulfill conditions to release
12
Oracles and Off-Chain Data
Chainlink, TWAP oracles, and the oracle problem. Bringing real-world data on-chain.
29 min

What You'll Learn

  • Oracle problem and solutions
  • Chainlink integration
  • TWAP oracle patterns

What You'll Do

  • Integrate Chainlink price feed
  • Build TWAP oracle
13
Cross-Chain and L2 Bridges
Rollups, bridges, and L1-L2 communication. Optimistic vs ZK rollups.
29 min

What You'll Learn

  • Rollup architecture
  • Bridge security models
  • L1-L2 messaging

What You'll Do

  • Send message between L1 and L2
  • Understand bridge risks
14
Production Key Management
Hardware wallets, multisig (Safe), key rotation, and operational security.
30 min

What You'll Learn

  • Key management hierarchy
  • Gnosis Safe multisig
  • Production security patterns

What You'll Do

  • Set up multisig
  • Implement key rotation
15
Internals: How the EVM Works
Stack machine, opcodes, gas metering, and memory layout. The machine under the abstraction.
30 min

What You'll Learn

  • EVM stack machine
  • Opcode execution
  • Gas metering internals

What You'll Do

  • Debug at opcode level
  • Analyze gas costs
Live Sandbox

Try Ethereum in your browser
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  • 3 blockchain codexes of your choice
  • Everything in Apprentice
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  • All 6 blockchain codexes
  • Everything in Practitioner
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