Blockchain & Web3 Development Skill — Quick Reference

This skill equips blockchain developers with execution-ready patterns for building secure, gas-optimized smart contracts and decentralized applications. Claude should apply these patterns when users ask for smart contract development, DeFi protocols, NFT implementations, security audits, or Web3 architecture.

Modern Best Practices: Security-first development, formal verification, comprehensive testing (unit, integration, fork, invariant), gas optimization, upgradeable contracts, multi-chain deployment, and battle-tested DeFi patterns.

Quick Reference

Task Tool/Framework Command When to Use

Solidity Development Hardhat/Foundry npx hardhat init or forge init

Ethereum/EVM smart contracts

Solana Programs Anchor anchor init

Solana blockchain development

Cosmos Contracts CosmWasm cargo generate --git cosmwasm-template

Cosmos ecosystem contracts

TON Contracts Tact/FunC + Blueprint npm create ton@latest

TON blockchain development

Testing (Solidity) Foundry/Hardhat forge test or npx hardhat test

Unit, fork, invariant tests

Security Audit Slither/Mythril/Echidna slither .

Static analysis, fuzzing

Gas Optimization Foundry Gas Snapshots forge snapshot

Benchmark and optimize gas

Deployment Hardhat Deploy/Forge Script npx hardhat deploy

Mainnet/testnet deployment

Verification Etherscan API npx hardhat verify

Source code verification

Upgradeable Contracts OpenZeppelin Upgrades @openzeppelin/hardhat-upgrades

Proxy-based upgrades

When to Use This Skill

Claude should invoke this skill when a user requests:

• Smart contract development (Solidity, Rust, CosmWasm)

• DeFi protocol implementation (AMM, lending, staking, yield farming)

• NFT and token standards (ERC20, ERC721, ERC1155, SPL tokens)

• DAO governance systems

• Cross-chain bridges and interoperability

• Gas optimization and storage patterns

• Smart contract security audits

• Testing strategies (Foundry, Hardhat, Anchor)

• Oracle integration (Chainlink, Pyth)

• Upgradeable contract patterns (proxies, diamonds)

• Web3 frontend integration (ethers.js, web3.js, @solana/web3.js)

• Blockchain indexing (The Graph, subgraphs)

• MEV protection and flashbots

• Layer 2 scaling solutions (Optimism, Arbitrum, zkSync)

• Backend crypto integration (.NET/C#, multi-provider architecture, CQRS)

• Webhook handling and signature validation (Fireblocks, custodial providers)

• Event-driven architecture with Kafka for crypto payments

• Transaction lifecycle management and monitoring

• Wallet management (custodial vs non-custodial)

Decision Tree: Blockchain Platform Selection

Project needs: [Use Case] ├─ EVM-compatible smart contracts? │ ├─ Complex testing needs → Foundry (Solidity tests, fuzzing, gas snapshots) │ ├─ TypeScript ecosystem → Hardhat (plugins, TypeScript, Ethers.js) │ └─ Enterprise features → NestJS + Hardhat │ ├─ High throughput/low fees? │ ├─ Rust-based → Solana (Anchor framework, 50k+ TPS) │ ├─ EVM L2 → Arbitrum/Optimism (Ethereum security, lower gas) │ └─ Telegram integration → TON (Tact/FunC contracts) │ ├─ Interoperability across chains? │ ├─ Cosmos ecosystem → CosmWasm (IBC protocol) │ ├─ Multi-chain DeFi → LayerZero or Wormhole │ └─ Bridge development → Custom bridge contracts │ ├─ Token standard implementation? │ ├─ Fungible tokens → ERC20 (OpenZeppelin), SPL Token (Solana) │ ├─ NFTs → ERC721/ERC1155 (OpenZeppelin), Metaplex (Solana) │ └─ Semi-fungible → ERC1155 (gaming, fractionalized NFTs) │ ├─ DeFi protocol development? │ ├─ AMM/DEX → Uniswap V3 fork or custom (x*y=k, concentrated liquidity) │ ├─ Lending → Compound/Aave fork (collateralized borrowing) │ └─ Staking/Yield → Custom reward distribution contracts │ ├─ Upgradeable contracts required? │ ├─ Transparent Proxy → OpenZeppelin (admin/user separation) │ ├─ UUPS → Gas-efficient (upgrade logic in implementation) │ └─ Diamond Standard → Modular functionality (EIP-2535) │ └─ Backend integration? ├─ .NET/C# → Multi-provider architecture (see Backend Integration Patterns) ├─ Node.js → Ethers.js/Web3.js + Prisma └─ Python → Web3.py + FastAPI

Chain-Specific Considerations:

• Ethereum/EVM: Security-first, higher gas costs, largest ecosystem

• Solana: Performance-first, Rust required, lower fees

• Cosmos: Interoperability-first, IBC native, growing ecosystem

• TON: Telegram-first, async contracts, unique architecture

See resources/ for chain-specific best practices.

Navigation

Resources

• resources/blockchain-best-practices.md — Universal blockchain patterns and security

• resources/backend-integration-best-practices.md — .NET/C# crypto integration patterns (CQRS, Kafka, multi-provider)

• resources/solidity-best-practices.md — Solidity/EVM-specific guidance

• resources/rust-solana-best-practices.md — Solana + Anchor patterns

• resources/cosmwasm-best-practices.md — Cosmos/CosmWasm guidance

• resources/ton-best-practices.md — TON contracts (Tact/Fift/FunC) and deployment

• ../software-security-appsec/resources/smart-contract-security-auditing.md — Smart contract audit workflows and tools (see software-security-appsec skill)

• README.md — Folder overview and usage notes

• data/sources.json — Curated external references per chain

Templates

• Ethereum/EVM: templates/ethereum/template-solidity-hardhat.md, templates/ethereum/template-solidity-foundry.md

• Solana: templates/solana/template-rust-anchor.md

• Cosmos: templates/cosmos/template-cosmwasm.md

• TON: templates/ton/template-tact-blueprint.md, templates/ton/template-func-blueprint.md

• Bitcoin: templates/bitcoin/template-bitcoin-core.md

Related Skills

• ../software-security-appsec/SKILL.md — Security hardening, threat modeling, OWASP vulnerabilities

• ../software-architecture-design/SKILL.md — System decomposition, modularity, dependency design

• ../ops-devops-platform/SKILL.md — Infrastructure, CI/CD, observability for blockchain nodes

• ../software-backend/SKILL.md — API integration with smart contracts, RPC nodes, indexers

• ../quality-resilience-patterns/SKILL.md — Resilience, circuit breakers, retry logic for chains

• ../software-code-review/SKILL.md — Code review patterns and quality gates

• ../foundation-api-design/SKILL.md — RESTful design for Web3 APIs and dApp backends

Operational Playbooks

• resources/operational-playbook.md — Smart contract architecture, security-first workflows, and platform-specific patterns