Heidelberg AICurriculum

I Built a Claude Code Skill That Starts Any App (Free)

Leon van Zyl ·2026-07-28 ·2 min read

Summary written by us from the video's transcript. The video, and everything in it, is Leon van Zyl's work.

Learn how to replace a traditional boilerplate repo with an AI-powered Claude Code skill that scaffolds a full app based on your answers.

Takeaways

  • Static boilerplates require manual cleanup and constant dependency updates.
  • A Claude Code skill can replace an entire starter repo, prompting you for requirements and generating only needed components.
  • Install a skill once with `npx skills add <repo>` and invoke it globally in any Claude session.
  • You can customize the underlying tech stack by editing the skill’s modular files.
  • Additional skills, like the OWASP security scanner, can be added to the same workflow.

Why boilerplates become cumbersome

Traditional starter kits bundle UI, backend, auth, and payment code into one repository. You run a single command, get the scaffold, then manually delete or replace parts you don’t need. Maintaining such templates is painful: dependencies go out of date, peer‑dependency conflicts arise, and updates must be retested for each new project.

Introducing an AI skill as a dynamic starter kit

Instead of downloading a static repo, the presenter created a **Claude Code skill** that contains all the logic for building a new app. Installing the skill once (via `npx skills add <repo‑url>`) makes it available globally or per project. When invoked, the agent asks clarifying questions and assembles only the components you actually require—no extra auth code, no unwanted payment modules.

How to install and explore the skill

Run `npx skills add https://github.com/leonfonsal/skills` (the URL is in the video description). The command creates an `agents/claude` folder with a single file: *start‑an‑app* skill. Inside you’ll find modular prompts, AI‑SDK setup, and rules for the author’s preferred “text stack” (Next.js, React, Better‑Auth, Drizzle ORM, PostgreSQL, Stripe/Polar, etc.). You can edit these files to swap libraries—e.g., replace Better‑Auth with Clerk—so future projects follow your custom defaults.

Running the skill to build a Trello‑style app

In Claude Code (desktop or web), type `use start an app skill to build a simple Trello clone`. The agent then walks you through questions: who can see boards, data model, drag‑and‑drop features, database choice (SQLite vs. PostgreSQL in Docker), authentication method, invitation flow, and landing‑page preference. Based on your answers it generates the full codebase with the selected stack, ready for local development or production deployment.

Extending the ecosystem: security scanner skill

A separate repository hosts a **security scanner** skill that runs an OWASP Top 10 audit on any generated project. Install it the same way (`npx skills add <repo‑url>`), then invoke it to produce a report in your project folder—useful because agents alone don’t perform comprehensive security checks.

When to use or modify the skill

The skill is aimed at non‑technical users who want an end‑to‑end setup without choosing a stack themselves. Technical architects can still fork the repo, adjust the `AI.md` and other config files, and keep the skill as a personal template. The skill only runs when you explicitly ask for it; you can interrupt or tell the agent not to use it at any point.