diff --git a/src/core/generator.py b/src/core/generator.py
new file mode 100644
index 0000000..c4b3904
--- /dev/null
+++ b/src/core/generator.py
@@ -0,0 +1,70 @@
+import json
+import os
+from pathlib import Path
+from .parser import parse_openapi_spec, load_spec_file
+from .models import Endpoint, APISpec
+
+
+def generate_docs(spec_file: str, output: str = None, format: str = 'html', open_browser: bool = False):
+    """Generate documentation in the specified format.
+
+    Args:
+        spec_file: Path to the OpenAPI spec file
+        output: Output file path or directory
+        format: Output format (html, markdown, json, all)
+        open_browser: Whether to open the generated file in browser
+    """
+    result = parse_openapi_spec(spec_file)
+
+    if not result.get('valid'):
+        raise ValueError(f"Invalid spec: {result.get('errors')}")
+
+    spec = result['spec']
+
+    if format == 'all':
+        for fmt in ['html', 'markdown', 'json']:
+            generate_docs(spec_file, output, fmt, open_browser and fmt == 'html')
+        return
+
+    if not output:
+        base_name = Path(spec_file).stem
+        if format == 'html':
+            output = f"{base_name}.html"
+        elif format == 'markdown':
+            output = f"{base_name}.md"
+        elif format == 'json':
+            output = f"{base_name}_docs.json"
+
+    if format == 'html':
+        from .templates.html_template import generate_html
+        generate_html(spec, output)
+    elif format == 'markdown':
+        from .templates.markdown_template import generate_markdown
+        generate_markdown(spec, output)
+    elif format == 'json':
+        generate_json_docs(spec, output)
+
+    print(f"Generated {format} documentation: {output}")
+
+    if open_browser and format == 'html':
+        import webbrowser
+        webbrowser.open(f'file://{os.path.abspath(output)}')
+
+
+def generate_json_docs(spec: dict, output: str):
+    """Generate JSON documentation."""
+    from .parser import extract_endpoints
+
+    endpoints = extract_endpoints(spec)
+
+    docs = {
+        'title': spec.get('info', {}).get('title', 'API Documentation'),
+        'version': spec.get('info', {}).get('version', '1.0.0'),
+        'description': spec.get('info', {}).get('description', ''),
+        'endpoints': endpoints,
+        'tags': spec.get('tags', []),
+        'servers': spec.get('servers', [])
+    }
+
+    with open(output, 'w') as f:
+        json.dump(docs, f, indent=2)