Spec-driven development tools help you write a spec first and then have an AI coding agent build from it. A year ago there were one or two. Now there are many, and they differ a lot in size, price and who they are for.
This post compares the spec-driven development tools teams ask us about most: GitHub Spec Kit, Kiro, OpenSpec, BMAD-METHOD and nTra. It also covers the option most people forget, which is no tool at all. For each one you get what it does, where it fits and where it gets in the way. If you are new to the idea, start with our spec-driven development guide.
The short answer
- Working alone or in a small team, and want it free: start with GitHub Spec Kit, or OpenSpec if most of your work is changes to an existing codebase.
- Want specs inside one editor: Kiro.
- Building something large from scratch and happy with a heavy process: BMAD-METHOD.
- A team where the business has to sign off what gets built: nTra.
- Just trying the idea: a markdown file per feature and your agent's plan mode.
What a spec-driven development tool should do
Before the tools, the yardstick. A good spec-driven development tool helps with five things:
- Write the spec. It asks the questions you forget and puts the answers in a fixed shape.
- Get it approved. A person who owns the outcome says yes before code starts.
- Break it into tasks. Each task names the requirement it serves and how you will know it is done.
- Drive the agent. The agent gets the task, the criteria and the rules, and nothing vague.
- Check the result. Something outside the agent checks the work against the criteria.
Most tools do the first, third and fourth well. Approval and checking are where they differ most.
GitHub Spec Kit
Spec Kit is an open-source toolkit from GitHub. You install a small CLI, and it adds slash commands to your coding agent. The flow goes from a constitution (your project's rules) to a spec, a plan, a task list and then implementation. Everything is saved as markdown files in your repo.
Good for: developers and small teams who want a free, well-known starting point. It works with many agents, including Copilot, Claude Code, Gemini CLI and Cursor.
Watch out for: approval and checking are up to you. The spec is a file, so nothing stops the code from drifting away from it after the first build. For larger teams, see our GitHub Spec Kit alternative post.
Kiro
Kiro is an agentic IDE from AWS built around specs. For a feature, it writes a requirements file, a design file and a task list, then works through the tasks inside the editor. Requirements use a structured format (EARS) that keeps each line short and testable. Steering files hold project rules, and hooks can run the agent when files change.
Good for: developers who want the whole spec flow inside one editor, with little setup.
Watch out for: you work in Kiro's IDE with Kiro's agent. If your team already uses Claude Code, Codex or Copilot, that is a switch. See our Kiro alternative post for that case.
OpenSpec
OpenSpec is a free, open-source framework built for changing code that already exists. Each change starts as a proposal with its tasks and the spec changes it makes. When the change is done, it is archived, and the main spec is updated to match. It works with many coding agents and needs no extra service.
Good for: teams with an existing product who want a light process for each change.
Watch out for: like Spec Kit, it lives in files. Approval and checking depend on your team's habits.
BMAD-METHOD
BMAD-METHOD is a free, open-source method that uses a set of agent roles: analyst, product manager, architect, scrum master, developer and QA. They produce a product brief, a PRD and an architecture document, then break the work into detailed story files for the developer agent.
Good for: larger new builds where you want every document, and you have time to learn the method.
Watch out for: it is heavy. Small changes take as much ceremony as big ones, and the learning curve is real.
nTra
nTra is a spec-driven product engineering platform for teams. The business signs off what gets built, and your own AI coding agents build it.
You start with a discovery chat that asks the questions a senior product manager would ask. A person approves the brief before anything is planned. nTra then writes the requirements and design, and breaks the work into tasks with Given/When/Then acceptance criteria. Each task runs through the agent each developer already uses: Claude Code, Codex or Copilot. When the agent says it is done, nTra re-runs the agent's own checks, and the re-run decides. Every task ends as a pull request a person approves.
Good for: teams where product, business and engineering all need to agree, and where you want proof that each requirement was met.
Watch out for: it is a paid platform, from $59 a month. For one developer on a side project, a free tool is enough.
No tool: markdown and plan mode
You do not need a tool to start. Write a one-page spec per feature in markdown: why, acceptance criteria, what is out of scope, and open questions. Put it in the repo. Ask your agent to plan from it before it writes code, and review the plan.
This is the best way to learn what a good spec looks like. It stops working when several people and several agents share the same specs, and nobody checks the code against them.
Spec-driven development tools at a glance
- GitHub Spec Kit: free and open source. Works with many agents. Specs live as files in your repo. Approval and checks are up to you.
- Kiro: its own IDE and agent. Requirements, design and tasks per feature. Free tier and paid plans.
- OpenSpec: free and open source. Built for changes to existing code. Works with many agents.
- BMAD-METHOD: free and open source. Many agent roles and documents. Heavy process.
- nTra: paid platform for teams. Business sign-off, Given/When/Then criteria, runs your own agents, re-runs checks, ends in a reviewed pull request.
How to choose
Ask three questions.
Who approves the spec? If it is the developer who writes the code, a file-based tool is fine. If a product owner or the business has to approve it, you need a place where they can read, comment and sign off, without opening a repo.
Which agents do you use? If everyone uses one editor, an IDE with specs built in is simple. If developers use different agents, pick a tool that sits above them and gives each one the same spec and rules.
What checks the result? Every agent says "done" with confidence. If nothing outside the agent re-runs the tests and checks each acceptance criterion, review becomes the only safety net. Look for a tool that does this for you, or build it into your CI.
Common mistakes when adopting a tool
- Picking the tool before writing one good spec by hand. You will not know what to look for.
- Using a heavy process for small changes. Match the weight of the process to the size of the change.
- Letting the agent write and approve its own spec. An agent can draft. A person has to approve.
- Stopping at the spec. A spec that nothing checks against becomes decoration. We wrote more about this in Don't just write the spec. Run it.
FAQ
What is the best spec-driven development tool?
It depends on the team. For one developer, GitHub Spec Kit or OpenSpec is a free and solid start. For one editor with specs built in, Kiro. For a team where the business has to sign off and every result is checked against the spec, nTra.
Are there free spec-driven development tools?
Yes. GitHub Spec Kit, OpenSpec and BMAD-METHOD are free and open source. You pay only for the AI coding agent you run them with.
Do spec-driven development tools work with Claude Code and Codex?
Most do. Spec Kit, OpenSpec and BMAD-METHOD work with many agents, including Claude Code and Codex. nTra runs Claude Code, Codex and Copilot. Kiro uses its own agent inside its own IDE.
Is GitHub Spec Kit the same as Kiro?
No. Spec Kit is a free toolkit that adds spec commands to the agent you already use, and keeps specs as files. Kiro is a full IDE from AWS with its own agent and a spec flow built in.
Do I need a tool for spec-driven development?
No. A markdown spec per feature, with testable acceptance criteria, is a valid start. A tool helps when many people and agents share specs and you want the results checked automatically.
Try it
Read the spec-driven development guide for a full example spec, or see how nTra works. Plans start at $59 a month on the pricing page, or book a demo to run one of your own features through it.