The language and the contracts written in it: token standards, vaults, proxies and upgradeability, account abstraction, and gas optimisation.
A large share of the category is adversarial: CTF and first-flight write-ups where a contract is broken deliberately, and the RareSkills interview series, which is a good measure of how well a pattern is actually understood.
43 posts
How Circle's UpgradableMSCA implements an ERC-6900 modular account: validation entities, hook ordering, ERC-7201 storage, and the factory that deploys it.
2026, Sep 09 —
A line-by-line reading of Circle's SponsorPaymaster, the ERC-4337 v0.7 verifying paymaster behind gasless Circle wallets, and the design choices behind it.
2026, Sep 09 —
A technical walkthrough of Centrifuge V3 vaults - the ERC-7540 request lifecycle, the pool escrow reservation model, the pricing and rounding rules, and the transfer hook.
2026, Aug 18 —
How Centrifuge implements real double-entry accounting in Solidity - debit-normal accounts, balanced journals, cross-chain snapshots, and the NAV and share price derived from them.
2026, Aug 18 —
A comparison of two enforcement architectures for regulated tokens - Centrifuge's single swappable hook with packed eligibility data, and ERC-3643's identity registry plus compliance modules.
2026, Aug 18 —
How Centrifuge routes messages between chains - per-pool adapter sets, an n-of-m vote counter that tolerates duplicates, transient batching, gas subsidies, and the recovery paths.
2026, Aug 18 —
A walkthrough of Alchemy's ERC-4337 stack — Modular Account V2 and its semi-modular variants, validation selection through the UserOperation nonce, deferred actions, session-key permission modules, the Rundler bundler, and the hosted Wallet APIs.
2026, Jul 30 —
How Medusa fuzzes Solidity contracts. Architecture, the corpus and coverage feedback loop, assertion, property and optimization tests, and a step-by-step setup on a real project.
2026, Jul 28 —
How the Gnosis Conditional Tokens contracts model prediction markets, why collection identifiers are elliptic curve points on alt_bn128, and what the 2019 audit found.
2026, Jul 28 —
How the ERC-4337 SenderCreator contract deploys smart accounts on behalf of the EntryPoint, how third parties read counterfactual addresses through getSenderAddress, and what changed across EntryPoint v0.6 to v0.9.
2026, Jul 23 —
Learn how to integrate Pyth Network pull oracle price feeds in Solidity and Solana programs, with a deep focus on security pitfalls — staleness, confidence intervals, fixed-point math, and adversarial selection.
2026, Mar 13 —
A deep technical analysis of the OpenZeppelin ERC-7984 Confidential Fungible Token implementation, covering the core accounting model, FHE-safe arithmetic, ACL access patterns, operator system, and the extension ecosystem.
2026, Feb 24 —
A technical comparison of Solidity modifier patterns — inline, wrapped function, and no-modifier — analyzing gas costs, bytecode size impact, auditability, and conventions across major codebases.
2026, Feb 18 —
Understanding the dual nonce system in ERC-4337 smart wallets, the differences between CREATE and CREATE2 for contract deployment, and the pitfalls encountered with EIP-7702 delegation.
2026, Feb 17 —
A practical security analysis of EIP-7702 smart wallets covering initialization front-running, access control, signature replay, dual nonce systems, and residual risks inherent to EOA code delegation.
2026, Feb 17 —
A technical comparison of ERC-20 token implementations across OpenZeppelin Contracts, Solady, and Solarity solidity-lib. Covers features, gas efficiency, architecture, extensibility, and selection criteria.
2026, Feb 13 —
A technical comparison of ERC-1271 and ERC-7913 signature verification across OpenZeppelin v5.5.0, Solady v0.1.26, Coinbase Smart Wallet v1.1.0, and Solarity solidity-lib v3.3.2. Covers architecture, features, gas, and selection criteria.
2026, Feb 13 —
This article describes how CMTAT implements flexible access control by separating business logic from authorization policy, allowing deployments to choose between RBAC, ownership, OpenZeppelin AccessManager, or custom policies.
2026, Jan 27 —
This article is an overview of the OpenZeppelin ERC-4337 Account contract. The content is mainly based on the OpenZeppelin documentation.
2025, Dec 13 —
This article summarizes the essential points to verify when reviewing a Solidity verifier contract using in zk-proof systems
2025, Nov 28 —
Tornado Cash is one of Ethereum’s pioneering privacy protocols build on zk-SNARK and Circom zero-knowledge circuits.
2025, Nov 19 —
This article presents the differences between abi.encode, abi.encodePacked, and abi.encodeWithSignature in Solidity. Use cases, examples, and security tips.
2025, Jul 29 —
This article explores data structures in OpenZeppelin Contracts v5, including EnumerableSet, DoubleEndedQueue, CircularBuffer, Checkpoints, Heap, and MerkleTree.
2025, Jul 29 —
First Fight 42 - Snowman Merkle Airdrop.
2025, Jul 11 —
First Fight 41 - SSSwap is aimed to be a minimalistic AMM on Solana.
2025, Jul 11 —
First Fight 38 - Rock Paper Scissors DApp is a fully decentralized implementation of the classic Rock Paper Scissors game on Ethereum.
2025, May 07 —
This article presents the different standards to represent cross-chain token on Ethereum and EVM blockchain, notably ERC-7281(xERC20) & ERC-7802
2025, May 07 —
This article presents a global overview of ERC-4337 which offers Account Abstraction on Ethereum using Alt Mempool and an entrypoint.
2025, May 02 —
Discover how Multicall enables batch execution of smart contract calls, when to use CALL vs DELEGATECALL, and how contract interactions differ from EOAs.
2025, Apr 03 —
This article presents a global overview of ERC-721 standard (NFT), covering its core functions, metadata, and security best practices and to build it with OpenZeppelin.
2025, Mar 03 —
Non-Fungible Tokens (NFTs) enable unique, verifiable ownership of digital and real-world items on the blockchain. While ERC-721 remains the main standard to represent NFTs on Ethereum and EVM blockchains, several other standards (ERC-1155, ERC-2981, ERC-4907,...) have emerged to meet various use cases and improve functionality.
2025, Jan 14 —
Solidity Interview Questions - Advanced, answers from the article - Solidity Interview Questions- by RareSkills.
2024, May 06 —
Solidity Interview questions - Hard, answers from the article - Solidity Interview Questions- by RareSkills.
2024, Mar 04 —
Solidity Interview questions - Medium, answers from the article - Solidity Interview Questions- by RareSkills.
2024, Feb 14 —
This article describes the challenge NotSuchSolidIT of Insomni'hack 2023
2023, Nov 08 —
This article summarizes the main and easier tricks to save gas with Solidity.
2023, Sep 26 —
This articles describes a correspondence table between the smart contract languages Solidity (Ethereum) and SmartPy / Python (Tezos).
2023, Jun 02 —
Summary of the most important points to think and check to program proxy contracts on Ethereum, with a focus on the OpenZeppelin library.
2022, Oct 31 —
There are different way to indicate the solidity version of the compiler. This article presents the advantages and disadvantages of each
2022, Oct 29 —
