Comparing Spec-Driven Development (SDD) Environments: SpecKit vs Kiro
Comparing Spec-Driven Development (SDD) Environments: SpecKit vs Kiro
Introduction
This article compares two representative approaches to implementing "Spec-Driven Development (SDD)," a methodology that has recently gained significant attention.
- VSCode + GitHub Copilot + SpecKit: Adding an SDD toolkit to existing editors
- Kiro IDE: An all-in-one IDE with integrated SDD features
What is Spec-Driven Development (SDD)?
In traditional development, code is central and specifications are supplementary. SDD reverses this by treating specifications as executable deliverables.
Key Benefits of SDD
- Clarification and documentation of requirements
- Precise instructions for AI agents
- Reduced misalignment between teams
- Support for iterative improvement processes
Environment 1: VSCode + GitHub Copilot + SpecKit
Overview
SpecKit is an open-source toolkit for implementing SDD in existing development environments. Provided by GitHub, it enables interaction with AI agents through slash commands.
Setup
# Install Specify CLI
uv tool install specify-cli --from git+https://github.com/github/spec-kit.git
# Initialize a new project
specify init my-project --ai copilot
# Or in an existing project
specify init . --ai copilot
Development Flow
1. Establish Project Constitution
/speckit.constitution Create principles focused on code quality,
testing standards, user experience consistency, and performance requirements
This command generates .specify/memory/constitution.md, defining project-wide guidelines.
2. Create Specifications
/speckit.specify Build an application that can help me organize my photos
in separate photo albums. Albums are grouped by date and can be re-organized
by dragging and dropping on the main page.
Generated files:
.specify/specs/001-feature-name/spec.md: Feature requirements and user stories
3. Create Technical Implementation Plan
/speckit.plan The application uses Vite with minimal number of libraries.
Use vanilla HTML, CSS, and JavaScript as much as possible.
Generated files:
plan.md: Technical architecturedata-model.md: Data model definitioncontracts/api-spec.json: API specificationsresearch.md: Technical research documentation
4. Task Decomposition
/speckit.tasks
Generated files:
tasks.md: Implementation task list (with dependencies and parallel execution markers)
5. Execute Implementation
/speckit.implement
Implementation proceeds sequentially based on the task list.
SpecKit Prompt File Details
SpecKit generates multiple prompt files in the .github/prompts/ directory.
speckit.constitution.prompt.md
Purpose: Define fundamental principles and development guidelines for the project
Structure:
---
description: Create or update project governing principles
---
# Project Constitution
Create a comprehensive constitution document that includes:
1. **Code Quality Standards**
- Naming conventions
- Documentation requirements
- Code review processes
2. **Testing Standards**
- Unit test coverage requirements
- Integration test strategies
- Test documentation
3. **Architecture Principles**
- Design patterns to follow
- Technology stack constraints
- Performance requirements
4. **User Experience Guidelines**
- Accessibility standards
- Responsive design requirements
- Internationalization considerations
Features:
- AI agents reference this document throughout all subsequent phases
- Enforces project-specific best practices
- Ensures consistency across teams
speckit.specify.prompt.md
Purpose: Structure feature requirements in user story format
Structure:
---
description: Define requirements and user stories
---
# Specification Template
## User Stories
**As a** [user type]
**I want** [goal]
**So that** [benefit]
### Acceptance Criteria
- [ ] Criterion 1
- [ ] Criterion 2
## Functional Requirements
### FR-001: [Requirement Name]
**Priority**: High/Medium/Low
**Description**: Detailed requirement description
**Dependencies**: [Other requirements]
Generation Process:
- Parse natural language description from user
- Convert to user stories
- Clarify acceptance criteria
- Assign functional requirement IDs
speckit.plan.prompt.md
Purpose: Detail technical implementation plans
Structure:
---
description: Create technical implementation plans
---
# Implementation Plan
## Technology Stack
- Frontend: [Framework/Library]
- Backend: [Framework]
- Database: [Type]
- Deployment: [Platform]
## Architecture Overview
[System architecture diagrams, component diagrams]
## Data Model
[Entity relationship diagrams, table definitions]
## API Specifications
[Endpoint definitions, request/response formats]
## Implementation Phases
1. Phase 1: [Core features]
2. Phase 2: [Advanced features]
## Technical Considerations
- Security requirements
- Performance optimization
- Scalability concerns
Features:
- Adheres to constitution.md principles
- Technically resolves spec.md requirements
- Compares multiple technology choices
speckit.tasks.prompt.md
Purpose: Decompose into concrete, implementable tasks
Structure:
---
description: Generate actionable task lists
---
# Task Breakdown
## User Story: [Story ID]
### Task 1: [Task Name]
**File**: `src/components/Feature.tsx`
**Type**: Implementation
**Dependencies**: None
**Parallel**: [P] (if parallelizable)
**Description**: Detailed task description
**Acceptance**: How to verify completion
### Task 2: [Task Name]
**File**: `tests/Feature.test.tsx`
**Type**: Testing
**Dependencies**: Task 1
Generation Rules:
- Explicitly manage dependencies
- Specify file paths concretely
- Consider Test-Driven Development (TDD) order
- Mark tasks that can be executed in parallel
speckit.implement.prompt.md
Purpose: Execute implementation based on task list
Execution Flow:
---
description: Execute implementation plan
---
# Implementation Execution
1. **Validate Prerequisites**
- Constitution exists
- Spec is complete
- Plan is approved
- Tasks are defined
2. **Parse Tasks**
- Read tasks.md
- Build dependency graph
- Identify parallel tasks
3. **Execute Tasks**
For each task in order:
- Create/modify specified files
- Run tests (if TDD)
- Validate against acceptance criteria
- Update task status
4. **Progress Reporting**
- Mark tasks as In Progress/Done
- Report errors with context
- Suggest next steps
speckit.clarify.prompt.md
Purpose: Clarify ambiguous parts of the specification through questions
Structure:
---
description: Clarify underspecified areas
---
# Clarification Questions
## Coverage Analysis
[Identify areas not covered in the specification]
## Sequential Questions
1. **Question**: [Specific question]
**Context**: [Why this is important]
**Options**: [Possible answers]
[Answers are added to Clarifications section when recorded]
Features:
- Recommended to execute before Plan creation
- Elicit answers through structured questions
- Answers are integrated into the specification
Example Generated Documents
In an actual project, the directory structure looks like this:
my-project/
├── .specify/
│ ├── memory/
│ │ └── constitution.md # Project principles
│ ├── specs/
│ │ └── 001-photo-albums/
│ │ ├── spec.md # Feature specifications
│ │ ├── plan.md # Implementation plan
│ │ ├── tasks.md # Task list
│ │ ├── data-model.md # Data model
│ │ ├── contracts/
│ │ │ └── api-spec.json # API specifications
│ │ └── research.md # Technical research
│ ├── scripts/
│ │ ├── create-new-feature.sh
│ │ └── setup-plan.sh
│ └── templates/
│ ├── spec-template.md
│ ├── plan-template.md
│ └── tasks-template.md
├── .github/
│ └── prompts/
│ ├── speckit.constitution.prompt.md
│ ├── speckit.specify.prompt.md
│ ├── speckit.plan.prompt.md
│ ├── speckit.tasks.prompt.md
│ ├── speckit.implement.prompt.md
│ ├── speckit.clarify.prompt.md
│ └── speckit.analyze.prompt.md
└── src/
└── [Implementation files]
Advantages
✅ Open Source: Free to use under MIT license
✅ Flexibility: Supports multiple AI agents (Claude, Gemini, Copilot, etc.)
✅ Gradual Adoption: Can adopt incrementally starting with needed features
Disadvantages
❌ Manual Setup: Initial configuration requires multiple steps
❌ Integration Complexity: Need to combine multiple tools
❌ UI Experience: Command-line centered with limited visual feedback
❌ Learning Curve: Need to understand the role and order of each command
Environment 2: Kiro IDE
Overview
Kiro is an Agentic IDE supporting from prototype to production, with natively integrated SDD features.
Setup
- Download the IDE from kiro.dev
- Install and launch
- Can automatically import VS Code settings and plugins
Development Flow
1. Generate Steering Docs
Select "Generate Steering Docs" from the Kiro panel to generate the following in .kiro/steering/:
- Project technology stack information
- Coding conventions
- Workflow guidelines
2. Three Phases of Spec Creation
Requirements Phase
Describe user stories and acceptance criteria in EARS (Easy Approach to Requirements Syntax) format:
WHEN [condition/event]
THE SYSTEM SHALL [expected behavior]
Generated file: .kiro/specs/feature-name/requirements.md
Design Phase
Document technical architecture and sequence diagrams:
Generated file: .kiro/specs/feature-name/design.md
Tasks Phase
Detailed plan for implementation tasks:
Generated file: .kiro/specs/feature-name/tasks.md
3. Automation with Hooks
Event-driven automation that automatically executes tasks in response to file changes:
Example: "When saving a React component, automatically generate test files"
{
"hooks": [
{
"trigger": "onFileSave",
"pattern": "**/*.tsx",
"action": "generateTests"
}
]
}
Kiro Document Structure
my-project/
├── .kiro/
│ ├── steering/
│ │ ├── tech-stack.md
│ │ ├── coding-standards.md
│ │ └── workflows.md
│ └── specs/
│ └── photo-albums/
│ ├── requirements.md # EARS format requirements
│ ├── design.md # Architecture design
│ └── tasks.md # Implementation tasks
└── src/
└── [Implementation files]
Advantages
✅ Integrated Experience: All features natively integrated in the IDE
✅ Visual UI: Visual management of spec lists and task statuses
✅ Automation: Background task execution with Hooks
Disadvantages
❌ Dedicated IDE Required: Need to migrate from existing editors
❌ Vendor Lock-in: Dependency on Kiro-specific features
Detailed Comparison Table
| Aspect | SpecKit | Kiro |
|---|---|---|
| Setup | Manual setup via CLI | Download & install only |
| Learning Curve | Need to learn commands | Intuitive UI |
| Spec Format | Markdown with templates | EARS + Markdown |
| Task Management | Text management in tasks.md | Visual management in IDE |
| Automation | Script-based | Event-driven with Hooks |
| Git Integration | Automatic branch-based management | Manual or IDE features |
| AI Agents | 10+ supported | Kiro integrated agent |
| Extensibility | Template customization | MCP + Powers |
| Cost | Free (OSS) | Free during preview |
| Team Sharing | Full sharing via Git | Git + Kiro-specific features |
Comparison of Generated Documents
Constitution/Steering
SpecKit:
.specify/memory/constitution.md: Single file- Describes overall project principles
- Referenced by all commands
Kiro:
.kiro/steering/: Multiple files- Separates tech stack, coding conventions, workflows
- Auto-generated + customizable
Specification
SpecKit:
# spec.md
## User Stories
As a user, I want to...
## Functional Requirements
FR-001: Feature description
## Review Checklist
- [ ] Requirements are clear
- [ ] Acceptance criteria defined
Kiro:
# requirements.md (EARS format)
WHEN user clicks upload button
THE SYSTEM SHALL display file selection dialog
WHEN file size exceeds 10MB
THE SYSTEM SHALL display error message
Implementation Plan
SpecKit:
# plan.md
## Architecture
- Frontend: React
- Backend: Node.js
## Implementation Details
[Detailed implementation guide]
# data-model.md
[Database schema]
# contracts/api-spec.json
{OpenAPI specification}
Kiro:
# design.md
## Component Architecture
[System architecture diagram]
## Sequence Diagrams
[Flow diagrams]
## Technical Considerations
[Performance, security, etc.]
Tasks
SpecKit:
# tasks.md
## User Story: US-001
### Task 1: Setup database schema
File: src/db/schema.sql
Dependencies: None
[P] Parallel: Yes
### Task 2: Create API endpoint
File: src/api/upload.ts
Dependencies: Task 1
Kiro:
# tasks.md
## Phase 1: Core Implementation
- [ ] Task 1: Database setup
Status: Not Started
Assignee: [Auto]
- [ ] Task 2: API development
Status: Not Started
Dependencies: Task 1
Usage Guidelines
When to Choose SpecKit
-
Want to maintain existing VSCode environment
- Use extensive plugins and settings as-is
- Avoid editor migration costs
-
Entire team is new to SDD
- Learn gradually with command-based approach
- Easy to share documents via Git
-
Want to try multiple AI agents
- Switch between Claude, Gemini, Copilot, etc.
- Avoid vendor lock-in
-
Open source priority
- Community-driven development
- Freedom to customize
When to Choose Kiro
-
Maximize productivity
- Work quickly with integrated UI
- Automate repetitive tasks with Hooks
-
Visual focus
- Manage specs and tasks visually
- Check progress on dashboard
-
Need advanced automation
- Event-driven workflows
- Integrate with external services via MCP
-
New projects
- Not bound to existing environment
- Try the latest SDD experience
Advanced Usage with SpecKit Prompt Files
Creating Custom Prompts
SpecKit prompt files can be freely customized:
---
description: Custom quality checklist generator
---
# /speckit.custom-checklist
Generate a quality checklist for:
1. **Security Review**
- Authentication check
- Authorization verification
- Input validation
2. **Performance Review**
- Database query optimization
- Caching strategy
- Load testing results
[Output format: Markdown checklist in spec directory]
Managing Multiple Specs
# Feature 1
specify init . --ai copilot
/speckit.specify Build user authentication system
# Feature 2 (on new branch)
git checkout -b feature/002-payment
/speckit.specify Integrate payment gateway
Practical Workflow Examples
Team Development with SpecKit
graph TD
A[Product Manager] -->|Define requirements| B["speckit.specify"]
B --> C["Generate spec.md"]
C --> D[Tech Lead]
D -->|Technology selection| E["speckit.plan"]
E --> F["Generate plan.md, data-model.md"]
F --> G[Developer]
G -->|Review tasks| H["speckit.tasks"]
H --> I["Generate tasks.md"]
I --> J["speckit.implement"]
J --> K["Generate code"]
K --> L[Pull Request]
L --> M[Code Review]
M -->|Approve| N[Merge]Team development flow with SpecKit: Different commands for different roles, sharing documents via Git
Solo Development with Kiro
graph TD
A[Idea] --> B[Spec Chat]
B --> C[Generate Requirements]
C --> D[Generate Design]
D --> E[Generate Tasks]
E --> F[Code with #spec reference]
F --> G[Save file]
G --> H[Trigger Hooks]
H --> I[Auto-generate tests]
I --> J[Run in background]Solo development flow with Kiro IDE: Efficient development cycle with integrated UI and automation via Hooks
Conclusion
SpecKit is ideal for teams that want to adopt SDD while leveraging existing development environments. It's open source, highly flexible, and allows gradual adoption.
Kiro is suited for developers seeking the latest Agentic IDE experience. With integrated UI, automation features, and visual feedback, it maximizes productivity.
Both environments aim to break away from traditional "vibe coding" and realize a systematic development process centered on specifications. Choose based on your project nature, team composition, and existing development environment.
- Try SpecKit: GitHub repo
- Try Kiro: Official site