saas-design-principles

fractional-cto: The AI CTO Co-Pilot for SaaS Engineering

98 skills, 24 commands, and 19 agents across 13 plugins. Opinionated, research-backed Claude Code plugins for building SaaS products that ship.

Designed for Claude Code and Cowork. Every skill also installs into 70+ other agents with one command — see Other AI assistants.

Start Here

Building a form? Skills activate automatically. Need an API review? /api-design-principles:api-review Auditing code quality? /pedantic-coder:pedantic-review Researching a topic? /deep-research:research "your question" Stress-testing a plan? /stress-test:stress-test path/to/plan.md Compressing your CLAUDE.md? /markdown-compressor:compress path/to/file.md Resetting your plan file? /planning-tools:plan-delete Chaining two agents across terminals? /agent-baton:baton-pass and /agent-baton:baton-wait

If this project helps you, star the repo.

Why fractional-cto?

Generic AI gives you suggestions. fractional-cto gives you standards.

Each skill encodes a proven engineering principle (naming precision, API design patterns, cloud governance) and enforces it the moment Claude detects relevant work. You get the rigor of Stripe's API design, Nielsen Norman's usability research, and production cloud architecture baked into every session. No bookshelf required.

The skills are deliberately opinionated. They don't present five options and ask you to choose. They tell you what to do, cite why, and show you the code. If you disagree, edit the skill. It's just markdown.

How It Works

Every plugin activates the moment your Claude session starts. A session hook fires, reads the plugin's skill index, and injects it into context. From that point on, Claude knows what principles exist and when to apply them.

Each plugin carries review checklists, good/bad pattern comparisons, working code examples, and a dedicated reviewer agent for deeper audits.

Installation

Claude Code / Cowork

# Step 1: Add the marketplace
/plugin marketplace add oborchers/fractional-cto

# Step 2: Install individual plugins
/plugin install saas-design-principles@fractional-cto
/plugin install visual-design-principles@fractional-cto
/plugin install api-design-principles@fractional-cto
/plugin install cloud-foundation-principles@fractional-cto
/plugin install pedantic-coder@fractional-cto
/plugin install python-package@fractional-cto
/plugin install deep-research@fractional-cto
/plugin install structured-brainstorming@fractional-cto
/plugin install retell@fractional-cto
/plugin install stress-test@fractional-cto
/plugin install markdown-compressor@fractional-cto
/plugin install planning-tools@fractional-cto
/plugin install agent-baton@fractional-cto

Other AI assistants (skills only)

All 98 skills install into any of 70+ agents with the skills CLI — Gemini CLI, Cursor, Codex, OpenCode, Copilot, Cline, Windsurf, and the rest. No copying, no npm package, nothing to keep in sync.

# Browse every skill in this marketplace without installing
npx skills add oborchers/fractional-cto --list

# Install one skill
npx skills add oborchers/fractional-cto --skill agent-baton

# Install a few
npx skills add oborchers/fractional-cto --skill naming-precision,form-design

# Install everything, for every agent it detects
npx skills add oborchers/fractional-cto --all

Add -g for user-level instead of project-level, and -a <agent> to target specific agents. The CLI symlinks to a canonical copy by default, so npx skills update pulls new versions; pass --copy for independent files.

What you get: skills only. Commands (/plugin-name:command) and agents are Claude-specific and do not travel — but every skill is written to stand on its own, so the guidance is complete without them.

Prefer to vendor the files yourself? The */skills/*/SKILL.md files follow the universal skill format and can simply be copied into your agent's skills directory (.gemini/skills/, .cursor/skills/, .codex/skills/, …).

Local Development

claude --plugin-dir /path/to/fractional-cto/<plugin-name>

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Available Plugins

1. saas-design-principles -- Speed, navigation, forms, tables, auth, accessibility (13 skills, 1 command, 1 agent)

Research-backed SaaS design principles drawn from Linear, Stripe, Shopify Polaris, and Nielsen Norman Group research.

Skills (13):