How It Works
Agents CodeScanner Brainstormer Designer StackAdvisor Phaser Deployer
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About

About Spec4

What Spec4 is

Spec4 AI is a project planning tool for developers who are already using — or planning to use — agentic coding tools for spec-driven development.

It's built on a simple observation: the quality of what an agentic coding tool produces is almost entirely determined by the quality of the spec it's given. Vague specs produce vague code. Incomplete specs produce incomplete code. Specs that grow organically as the conversation progresses lead to drift, contradiction, and rework.

Spec4 makes the spec the first-class artifact. Six specialized agents — each with a distinct role and a clear handoff — work together to build a spec, a UI mock, and a deployment plan that are precise, complete, and structured exactly the way a coding agent needs them.

The pipeline at a glance

Agent Role Output
CodeScanner (optional) Reads an existing codebase and confirms the current state code_review.json
Brainstormer Collaborates on the project vision through structured dialogue vision.json
Designer (optional) Generates a self-contained HTML mock of the application UI design/mock.html
StackAdvisor Guides technology stack selection with trade-off analysis stack.json
Phaser Breaks the build into phase-by-phase implementation prompts phases/*.json
Deployer Plans the deployment strategy and coding agent workflow deployment-plan.md

Design principles

One question at a time.
Every agent in Spec4 asks one focused question and waits for your answer. No overwhelming forms, no multi-part questions, no assumptions. The pace is yours.
Confirmed, not assumed.
Every finding is confirmed with you before it moves forward. Every technical standard is verified against canonical documentation. Every dependency is added to the spec only after you approve it.
Bring your own everything.
Spec4 is provider-agnostic. Choose the AI model that fits your budget and preference. Use whatever agentic coding tool you work with. The output is plain JSON — yours to use however you like.
Downstream quality starts upstream.
Each agent's output is designed to feed the next. A thorough code review leads to better stack recommendations. A complete vision leads to more accurate phases. The pipeline is only as good as each handoff.

Who Spec4 is for

Spec4 is for developers who are already using — or planning to use — agentic coding tools, and who want to get more reliable, consistent results from them. It's particularly useful when:

The project is complex enough that a single prompt won't cut it
You're working on an existing codebase and need to plan a significant change
You want a repeatable, structured process rather than ad-hoc prompting
You're working with a team and need a shared, documented plan before implementation begins

Open source

Spec4 is free to use. Source code, contribution guidelines, and the roadmap are available on GitHub.

View on GitHub

Stop prompting. Start speccing.

Spec4 is free to use. Bring your own AI provider and model.

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