Spec-Driven Development
Writing a structured spec before any code so AI coding agents execute against it — the methodology I practise, template and write about.
Spec-driven development (SDD) is a methodology in which every feature starts with a specification rich enough for an AI coding agent to execute: scope, acceptance criteria, edge cases, architecture and a task breakdown. The spec stops being documentation next to the code and becomes the input that produces it.
How I use it
- Writing — SDD is the main theme of my blog: a primer (What Is Spec-Driven Development? A 2026 Primer), a complete guide to GSD (Spec-Driven Development with GSD: A Complete Guide), a three-way comparison (Spec-Driven Development: GSD vs Spec Kit vs OpenSpec), hands-on reviews of OpenSpec (OpenSpec Explained: A Hands-On Guide for 2026) and GitHub Spec Kit (GitHub Spec Kit: A Hands-On Review for 2026), an architecture deep dive (Inside GSD 2.0: The Architecture Behind Reliable AI Agents), a migration guide (Migrating From OpenSpec to GSD: When It's Worth It) and a week-long diary of shipping this site with it (A Week of Spec-Driven Development With GSD).
- Spec Dev Ralph — my starter template and guide for applying the methodology.
- Practice — I shipped NovaMX CRM and this site spec-first with Claude Code, and AI-assisted, spec-driven development is part of how I work in my current role.