Spec Kit
Open-source scaffold from GitHub that operationalizes spec-driven development with AI coding agents. Creates structured .specify/ folders that serve as the source of truth for Claude Code, GitHub Copilot, and Gemini CLI — steering AI generation from upfront specs rather than improvised prompts.
Claude Code
Terminal-first agentic coding assistant from Anthropic. Full MCP client support, codebase-aware, runs multi-step tasks autonomously.