diff --git a/.src/openapi_mock/core/spec_parser.py b/.src/openapi_mock/core/spec_parser.py
new file mode 100644
index 0000000..5df82a3
--- /dev/null
+++ b/.src/openapi_mock/core/spec_parser.py
@@ -0,0 +1,203 @@
+"""Parse and validate OpenAPI specifications."""
+
+import yaml
+from pathlib import Path
+from typing import Any, Dict, List, Optional, Tuple
+from openapi_spec_validator import validate
+from openapi_spec_validator.versions import consts as validator_consts
+
+
+class OpenAPISpecError(Exception):
+    """Base exception for OpenAPI spec errors."""
+    pass
+
+
+class SpecValidationError(OpenAPISpecError):
+    """Raised when OpenAPI spec validation fails."""
+    pass
+
+
+class SpecNotFoundError(OpenAPISpecError):
+    """Raised when OpenAPI spec file is not found."""
+    pass
+
+
+def load_spec(spec_path: str) -> Dict[str, Any]:
+    """Load and parse an OpenAPI specification from a YAML or JSON file.
+
+    Args:
+        spec_path: Path to the OpenAPI specification file.
+
+    Returns:
+        Parsed OpenAPI specification as a dictionary.
+
+    Raises:
+        SpecNotFoundError: If the spec file does not exist.
+        SpecValidationError: If the spec is invalid.
+    """
+    path = Path(spec_path)
+    if not path.exists():
+        raise SpecNotFoundError(f"OpenAPI spec file not found: {spec_path}")
+
+    try:
+        with open(path, 'r', encoding='utf-8') as f:
+            spec = yaml.safe_load(f)
+    except yaml.YAMLError as e:
+        raise OpenAPISpecError(f"Invalid YAML syntax in {spec_path}: {e}")
+    except IOError as e:
+        raise OpenAPISpecError(f"Error reading {spec_path}: {e}")
+
+    if spec is None:
+        raise OpenAPISpecError(f"Empty specification file: {spec_path}")
+
+    try:
+        validate(spec)
+    except Exception as e:
+        raise SpecValidationError(f"OpenAPI spec validation failed: {e}")
+
+    return spec
+
+
+def extract_paths(spec: Dict[str, Any]) -> Dict[str, Dict[str, Any]]:
+    """Extract all paths and their operations from an OpenAPI spec.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        Dictionary mapping path strings to operation dictionaries.
+    """
+    return spec.get('paths', {})
+
+
+def extract_schemas(spec: Dict[str, Any]) -> Dict[str, Any]:
+    """Extract all schemas from an OpenAPI spec.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        Dictionary mapping schema names to schema definitions.
+    """
+    components = spec.get('components', {})
+    schemas = components.get('schemas', {})
+
+    if not schemas and 'definitions' in spec:
+        schemas = spec.get('definitions', {})
+
+    return schemas
+
+
+def extract_path_params(path: str) -> List[str]:
+    """Extract parameter names from a path string.
+
+    Args:
+        path: API path string like '/users/{id}/posts/{post_id}'.
+
+    Returns:
+        List of parameter names without braces.
+    """
+    import re
+    params = re.findall(r'\{([^}]+)\}', path)
+    return params
+
+
+def get_operation_id(path: str, method: str) -> str:
+    """Generate an operation ID for a path/method combination.
+
+    Args:
+        path: API path string.
+        method: HTTP method (get, post, put, delete, etc.).
+
+    Returns:
+        Generated operation ID string.
+    """
+    import re
+    clean_path = path.lstrip('/').replace('/', '_').replace('-', '_')
+    params = re.findall(r'\{([^}]+)\}', clean_path)
+    for param in params:
+        clean_path = clean_path.replace(f'{{{param}}}', f'_{param}_')
+    method = method.lower()
+    return f"{method}_{clean_path}"
+
+
+def extract_security_schemes(spec: Dict[str, Any]) -> Dict[str, Any]:
+    """Extract security schemes from an OpenAPI spec.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        Dictionary mapping security scheme names to scheme definitions.
+    """
+    components = spec.get('components', {})
+    return components.get('securitySchemes', {})
+
+
+def extract_global_security(spec: Dict[str, Any]) -> List[Dict[str, List[str]]]:
+    """Extract global security requirements from an OpenAPI spec.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        List of security requirement dictionaries.
+    """
+    return spec.get('security', [])
+
+
+def get_response_schema(
+    spec: Dict[str, Any],
+    path: str,
+    method: str,
+    status_code: str = '200'
+) -> Optional[Dict[str, Any]]:
+    """Get the response schema for a specific path/method/status_code.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+        path: API path string.
+        method: HTTP method.
+        status_code: Response status code.
+
+    Returns:
+        Response schema definition or None if not found.
+    """
+    paths = spec.get('paths', {})
+    path_item = paths.get(path, {})
+    operation = path_item.get(method.lower(), {})
+
+    responses = operation.get('responses', {})
+    response = responses.get(status_code, responses.get('default', {}))
+
+    content = response.get('content', {})
+    if 'application/json' in content:
+        media_type = content['application/json']
+        return media_type.get('schema')
+
+    return None
+
+
+def get_spec_version(spec: Dict[str, Any]) -> str:
+    """Get the OpenAPI version from the spec.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        OpenAPI version string (e.g., "3.0.3", "2.0").
+    """
+    return spec.get('openapi', spec.get('swagger', 'unknown'))
+
+
+def is_openapi_3(spec: Dict[str, Any]) -> bool:
+    """Check if the spec is OpenAPI 3.x.
+
+    Args:
+        spec: Parsed OpenAPI specification.
+
+    Returns:
+        True if OpenAPI 3.x, False if Swagger 2.0.
+    """
+    openapi_version = spec.get('openapi', '')
+    return openapi_version.startswith('3.')