Who Built This Before Me

who-built-this-before-me

A skill for Claude Code that checks whether your idea has already been built before you invest time in it. It searches the landscape, clusters what exists, benchmarks your angle against prior art, and delivers a direct verdict: build, fork, contribute, use what's out there, or investigate why someone else gave up.

Installation

Claude Code

Clone directly into Claude Code's skills directory:

mkdir -p ~/.claude/skills
git clone https://github.com/iagochavarry/who-built-this-before-me.git ~/.claude/skills/who-built-this-before-me

Or copy the skill file manually if you already have this repo cloned:

mkdir -p ~/.claude/skills/who-built-this-before-me
cp SKILL.md ~/.claude/skills/who-built-this-before-me/

OpenCode

Clone directly into OpenCode's skills directory:

mkdir -p ~/.config/opencode/skills
git clone https://github.com/iagochavarry/who-built-this-before-me.git ~/.config/opencode/skills/who-built-this-before-me

Or copy the skill file manually if you already have this repo cloned:

mkdir -p ~/.config/opencode/skills/who-built-this-before-me
cp SKILL.md ~/.config/opencode/skills/who-built-this-before-me/

Note: OpenCode also scans `~/.claude/skills/` for compatibility, so a single clone into `~/.claude/skills/who-built-this-before-me/` works for both tools.

Usage

Claude Code

/who-built-this-before-me

I'm thinking of building [your idea here]

OpenCode

/who-built-this-before-me

I'm thinking of building [your idea here]

Or just describe the idea directly in either tool — the skill triggers on phrases like "I want to build…", "I'm thinking of making…", "should I build X…", or "is there already a…":

I want to build a CLI that auto-generates database migrations from OpenAPI schemas. Has anyone done this?

What you get back

A one-screen report with these sections:

• The idea, restated — your pitch stripped to one sentence, so you