Languages & Frameworks for Claude Code

Generate multiple radically different interface designs for a module using parallel sub-agents. Use when user wants to design an API, explore interface options, compare module shapes, or mentions "design it twice".

Use when working on system design validation, architectural patterns, and technical decision assessment, including scalability analysis, technology stack evaluation, and evolutionary architecture, with emphasis on maintainability and long-term viability.

Authentication patterns: session vs JWT vs OAuth comparison, provider selection (NextAuth, Clerk, Supabase Auth), security checklist, and common mistakes. Use when implementing auth, reviewing auth flows, or choosing auth providers.

Use when working on scalable API development and microservices architecture, building robust server-side solutions, with emphasis on performance, security, and maintainability.

Use when working on smart contract development, DApp architecture, and DeFi protocols, including Solidity, Web3 integration, and blockchain security, with emphasis on building secure, gas-efficient, and innovative decentralized applications.

Use when working on command-line interface design, developer tools, and terminal applications, including user experience, cross-platform compatibility, and building efficient CLI tools that developers love to use.

Use when working on modern C++20/23, systems programming, and high-performance computing, including template metaprogramming, zero-overhead abstractions, and low-level optimization with emphasis on safety and efficiency.

Use when working on modern .NET development, ASP.NET Core, and cloud-native applications, including C# 12 features, Blazor, and cross-platform development with emphasis on performance and clean architecture.

Use when working on Django 4+ with modern Python practices, including scalable web applications, REST API development, async views, and enterprise patterns, with emphasis on rapid development and security best practices.

Use when working on .NET Core, .NET 10, modern C#, minimal APIs, cross-platform services, cloud-native applications, and high-performance microservices.

Use when maintaining, debugging, or modernizing .NET Framework 4.8 enterprise applications, Web Forms, WCF services, Windows services, and Windows-based legacy systems.

Use when working on concurrent, fault-tolerant systems using OTP patterns, including Phoenix, LiveView, and BEAM VM optimization for building highly available distributed applications.

Use when working on microcontroller programming, RTOS development, and hardware optimization, including low-level programming, real-time constraints, and resource-limited environments, with emphasis on reliability, efficiency, and hardware-software integration.

Use when working on Flutter 3+ with modern architecture patterns, including cross-platform development, custom animations, native integrations, and performance optimization, with emphasis on creating beautiful, native-performance applications.

Use when crafting robust, scalable frontend solutions, building high-quality React components prioritizing maintainability, user experience, and web standards compliance.

Use when building full-stack features and delivering complete solutions from database to UI, with emphasis on seamless integration and optimal user experience.

Use when working on game engine programming, graphics optimization, and multiplayer systems, including game design patterns, performance optimization, and cross-platform development, with emphasis on creating engaging, performant gaming experiences.

Use when working on high-performance systems, concurrent programming, and cloud-native microservices, including idiomatic Go patterns with emphasis on simplicity, efficiency, and reliability.

Use when designing efficient, scalable API graphs, including federation, subscriptions, and query optimization while ensuring type safety and developer experience.

Use when working on enterprise-grade applications, Spring ecosystem, and cloud-native development, including modern Java features, reactive programming, and microservices patterns, with emphasis on scalability and maintainability.

Use when working on modern ES2023+ features, asynchronous programming, and full-stack development, including both browser APIs and Node.js ecosystem with emphasis on performance and clean code patterns.

Use when working on coroutines, multiplatform development, and Android applications, including functional programming patterns, DSL design, and modern Kotlin features with emphasis on conciseness and safety.

Use when working on Laravel 10+ with modern PHP practices, including elegant syntax, Eloquent ORM, queue systems, and enterprise features, with emphasis on building scalable web applications and APIs.

Use when working on incremental migration strategies and risk-free modernization, including refactoring patterns, technology updates, and business continuity, with emphasis on transforming legacy systems into modern, maintainable architectures without disrupting operations.

This skill should be used when setting up, auditing, or enforcing internationalization/localization in UI codebases (React/TS, i18next or similar, JSON locales), including installing/configuring the i18n framework, replacing hard-coded strings, ensuring en-US/zh-CN coverage, mapping error codes to localized messages, and validating key parity, pluralization, and formatting.

Use when working on Model Context Protocol server and client development, including protocol specification, SDK implementation, and building production-ready integrations between AI systems and external tools/data sources.

Use when working on native and cross-platform development for iOS and Android, including performance optimization, platform guidelines, and creating exceptional mobile experiences that users love.

Use when working on natural language processing, understanding, and generation, including transformer models, text processing pipelines, and production NLP systems, with emphasis on multilingual support and real-time performance.

Use when working on modern PHP 8.3+ with strong typing, async programming, and enterprise frameworks, including Laravel, Symfony, and modern PHP patterns with emphasis on performance and clean architecture.

Step-by-step migration guides for moving to Playwright from Cypress or Selenium/WebDriver — command mappings, architecture changes, and incremental adoption strategies.

Page Object Model patterns for Playwright — when to use POM, how to structure page objects, and when fixtures or helpers are a better fit.

Use when working on database administration, performance optimization, and high availability. Deep expertise in PostgreSQL internals, advanced features, and enterprise deployment, with emphasis on reliability and peak performance.

Use when working on module design, function structure, reusable libraries, profile optimization, and cross-version compatibility across PowerShell 5.1 and PowerShell 7+.

Use when working on modern Python 3.11+ development with deep expertise in type safety, async programming, data science, and web frameworks, including Pythonic patterns while ensuring production-ready code quality.

React Three Fiber animation - useFrame, useAnimations, spring physics, keyframes. Use when animating objects, playing GLTF animations, creating procedural motion, or implementing physics-based movement.

React Three Fiber (R3F) and Poimandres ecosystem best practices. Use when writing, reviewing, or optimizing R3F code. Triggers on tasks involving @react-three/fiber, @react-three/drei, zustand, @react-three/postprocessing, @react-three/rapier, or leva.

Use when working on Rails 8.1 with modern conventions, including convention over configuration, Hotwire/Turbo, Action Cable, and rapid application development, with emphasis on building elegant, maintainable web applications.

Use when working on React 18+ with modern patterns and ecosystem, including performance optimization, advanced hooks, server components, and production-ready architectures, with emphasis on creating scalable, maintainable applications.

Generates RESTful API documentation (OpenAPI 3.0 / Swagger spec) by scanning route definitions in code for Flask, FastAPI, Express, Gin, and other frameworks. Trigger when users ask about API documentation, OpenAPI, Swagger, endpoint docs, generating docs from code, or extracting endpoints.