Spec Kit
Define what to build before building it, with any AI coding agent
About Spec Kit
Spec Kit is GitHub's open source toolkit for Spec-Driven Development. It is a CLI called specify that scaffolds a structured process into a repository and installs the matching slash commands for whichever coding agent you use. The default process is Spec, then Plan, then Tasks, then Implement, and each phase produces a Markdown artefact the next phase reads, so the agent works from a written intent rather than from an ad-hoc prompt. Since 1.0.0 on 2026-08-21 it describes itself as an intent-driven harness rather than a single methodology: the SDD process ships ready to use, but presets, extensions, workflows and bundles let you tune it, extend it, automate it end to end, or replace it with a process of your own.
The problem it addresses is the one everyone running an agent on a real codebase hits: the agent is capable, but the instruction was a sentence, and the result reflects that. Spec Kit makes the specification a first-class artefact with templates, quality checklists and cross-artefact analysis, and it does this for 38 agent integrations - Copilot, Codex, Claude Code, Gemini, Kilo Code, Zed, Kiro, Muse Code and more - with a single command to switch between them. The traction is the largest of anything in this batch: 135,595 GitHub stars, 12,190 forks and roughly 290 contributors, with 157 community extensions and 33 presets at the time of writing. The licence is MIT, there is no paid tier, and the enterprise material is about running offline and hosting your own catalog, not a product.
You install the CLI with uv tool install specify-cli and run specify init my-project --integration copilot (or any other integration) in a new or existing repository. Spec Kit writes the command files and directory structure for that agent. From then on you work through the phases inside the agent: write the spec from a template that asks the questions a spec should answer, generate a plan against it, break the plan into tasks, and let the agent implement task by task. The checklists and cross-artefact analysis catch a plan that drifts from its spec before code is written. You can run each step by hand or chain them as an automated workflow. Presets change the flavour of the process, extensions add steps or gates (community examples include CI Guard and Architecture Guard for compliance), and bundles package a whole setup so a team installs the same thing. Everything is Markdown and templates in the repo, so it works offline, behind a firewall, and on Windows, macOS and Linux.
- •Spec, Plan, Tasks, Implement - A ready-to-use process where each phase produces a Markdown artefact the next one consumes
- •38 Agent Integrations - One command switches the same process between Copilot, Codex, Claude Code, Gemini, Zed, Kiro and others
- •Templates and Checklists - Structured prompts for each artefact plus quality gates and cross-artefact analysis
- •Presets, Extensions, Workflows, Bundles - Tune, extend, automate or fully replace the default process and share the result
- •Bug Fixing and Idea Assessment - Additional built-in processes beyond feature work, per the README
- •Self-Hosted Catalogs - Curate which integrations, extensions and presets your organisation discovers, offline if needed
Teams and solo developers who want a coding agent to work from a written specification rather than a chat message, and especially teams that switch between agents and want one process across all of them. It suits feature work of a size that deserves a plan. It is the wrong tool for a one-line fix, where the phases are pure ceremony, and it is a second process for teams that already have a planning discipline they like. The value is entirely in whether people actually write the specs; the tooling cannot make them. Readers who want a single opinionated agent with the workflow baked in will find this is deliberately the opposite: a process layer that assumes you bring the agent.
Pricing
No pricing page found
Free and MIT licensed. No paid tier and no pricing page; installs with uv or pip.
Checked 2026-09-15
