diff --git a/gen_docs.py b/gen_docs.py
new file mode 100644
index 0000000..d4d9331
--- /dev/null
+++ b/gen_docs.py
@@ -0,0 +1,157 @@
+#!/usr/bin/env python
+"""Generate API.md from the *openapi.json files in sources/."""
+import json
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent
+SOURCES = ROOT / "sources"
+GATEWAY_URL = "https://notifier.gansejunge.com/internal/"
+
+HTTP_METHODS = {"get", "post", "put", "patch", "delete", "head", "options"}
+
+
+def resolve(schema, spec):
+	"""Follow $ref pointers like #/components/schemas/Foo."""
+	while "$ref" in schema:
+		node = spec
+		for part in schema["$ref"].lstrip("#/").split("/"):
+			node = node[part]
+		schema = node
+	return schema
+
+
+def example(schema, spec, depth=0):
+	"""Build an example value from a JSON schema."""
+	if depth > 6:
+		return None
+	s = resolve(schema, spec)
+	if "example" in s:
+		return s["example"]
+	if "default" in s:
+		return s["default"]
+	if "enum" in s:
+		return s["enum"][0]
+	for key in ("anyOf", "oneOf"):
+		if key in s:
+			options = [o for o in s[key] if o.get("type") != "null"]
+			return example(options[0], spec, depth + 1) if options else None
+	if "allOf" in s:
+		return example(s["allOf"][0], spec, depth + 1)
+	t = s.get("type")
+	if t == "object" or "properties" in s:
+		return {k: example(v, spec, depth + 1) for k, v in s.get("properties", {}).items()}
+	if t == "array":
+		return [example(s.get("items", {}), spec, depth + 1)]
+	return {"string": "string", "integer": 0, "number": 0.0, "boolean": True}.get(t)
+
+
+def type_label(schema, spec):
+	s = resolve(schema, spec)
+	for key in ("anyOf", "oneOf"):
+		if key in s:
+			return " | ".join(type_label(o, spec) for o in s[key])
+	if s.get("type") == "array":
+		return f"array[{type_label(s.get('items', {}), spec)}]"
+	return s.get("type", "object" if "properties" in s else "any")
+
+
+def build_url(base, path, params):
+	url = base + path
+	for p in params:
+		if p["in"] == "path":
+			url = url.replace("{%s}" % p["name"], f"<{p['name']}>")
+	required_query = [p["name"] for p in params if p["in"] == "query" and p.get("required")]
+	if required_query:
+		url += "?" + "&".join(f"{q}=<{q}>" for q in required_query)
+	return url
+
+
+def render_operation(base, path, method, op, path_params, spec):
+	params = path_params + op.get("parameters", [])
+	out = [f"### `{method.upper()} {path}`\n"]
+
+	if op.get("summary"):
+		out.append(f"**{op['summary']}**\n")
+	if op.get("description"):
+		out.append(op["description"] + "\n")
+
+	if params:
+		out.append("| Name | In | Type | Required |")
+		out.append("|---|---|---|---|")
+		for p in params:
+			p = resolve(p, spec)
+			out.append(
+				f"| `{p['name']}` | {p['in']} | "
+				f"{type_label(p.get('schema', {}), spec)} | {'yes' if p.get('required') else 'no'} |"
+			)
+		out.append("")
+
+	curl = [f"curl -X {method.upper()} '{build_url(base, path, params)}'"]
+	curl.append("  -H 'X-API-Key: <api_key>'")
+
+	body = op.get("requestBody", {}).get("content", {})
+	if "application/json" in body:
+		ex = example(body["application/json"].get("schema", {}), spec)
+		out.append("**Request body:**\n")
+		out.append("```json\n" + json.dumps(ex, indent=2) + "\n```\n")
+		curl.append("  -H 'Content-Type: application/json'")
+		curl.append("  -d '" + json.dumps(ex) + "'")
+	elif body:
+		out.append(f"**Request body:** `{', '.join(body)}`\n")
+
+	out.append("**Example:**\n")
+	out.append("```bash\n" + " \\\n".join(curl) + "\n```\n")
+
+	responses = op.get("responses", {})
+	if responses:
+		out.append("**Responses:**\n")
+		for code, resp in responses.items():
+			resp = resolve(resp, spec)
+			line = f"- `{code}`: {resp.get('description', '')}"
+			json_content = resp.get("content", {}).get("application/json")
+			if json_content and "schema" in json_content:
+				ex = example(json_content["schema"], spec)
+				if ex is not None:
+					line += "\n  ```json\n  " + json.dumps(ex, indent=2).replace("\n", "\n  ") + "\n  ```"
+			out.append(line)
+		out.append("")
+
+	return "\n".join(out)
+
+
+def render_service(spec, source_name):
+	title = spec.get("info", {}).get("title")
+	if not title:
+		raise ValueError(f"{source_name} has no info.title")
+
+	# The title is the path segment on the gateway
+	base = GATEWAY_URL.rstrip("/") + "/" + title.strip("/")
+
+	out = [f"# {title}\n", f"Base URL: `{base}`\n"]
+	for path, item in sorted(spec.get("paths", {}).items()):
+		path_params = item.get("parameters", [])
+		for method, op in item.items():
+			if method in HTTP_METHODS:
+				out.append(render_operation(base, path, method, op, path_params, spec))
+	return title, "\n".join(out)
+
+
+def main():
+	files = sorted(SOURCES.rglob("*openapi.json"))
+	if not files:
+		print(f"No *openapi.json files found in {SOURCES}")
+		return 1
+
+	for f in files:
+		try:
+			title, markdown = render_service(json.loads(f.read_text(encoding="utf-8")), f.name)
+			safe_title = title.strip("/").replace("/", "-")
+			out_file = ROOT / f"API-{safe_title}.md"
+			out_file.write_text(markdown, encoding="utf-8")
+			print(f"OK   {f.relative_to(ROOT)} -> {out_file.name}")
+		except Exception as e:
+			print(f"FAIL {f.relative_to(ROOT)}: {e}")
+	return 0
+
+if __name__ == "__main__":
+	raise SystemExit(main())
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