What is spec-driven development (SDD)?

Updated Oct 26, 2026 · Sources listed at the end

Spec-driven development (SDD) means you first write down what to build and why (a specification), then have an AI coding agent turn it into a technical plan, a task list and finally code, reviewing each step. It is the opposite end of the spectrum from vibe coding.

GitHub Spec Kit

GitHub’s open-source Spec Kit describes SDD as “Define what to build and why, then turn the specification into a plan, tasks, and working code.” You create a project “constitution” once, then repeat the remaining steps for each feature, running them as skills in your agent’s chat (for example /speckit-constitution and /speckit-specify) and reviewing each result before continuing.¹

Kiro specs

Amazon’s Kiro builds specs into the product. A feature spec produces three files:²

• requirements.md (or bugfix.md): user stories and acceptance criteria, or bug analysis
• design.md: architecture, sequence diagrams, implementation notes
• tasks.md: discrete, trackable implementation tasks

When to use it

SDD costs more time up front but leaves a written record of intent that reviewers and future agents can check work against. For quick prototypes, plain prompting is usually enough.

Tools mentioned

• Kiro: free plan, paid from $20/mo
• GitHub Copilot: free plan, paid from $10/mo
• Claude Code: paid from $20/mo

Sources

1. GitHub: Spec Kit repository
2. Kiro docs: Specs