diff --git a/mlcli/automl/base_automl.py b/mlcli/automl/base_automl.py
new file mode 100644
index 0000000..86ae8ad
--- /dev/null
+++ b/mlcli/automl/base_automl.py
@@ -0,0 +1,306 @@
+"""
+Base AutoML Abstract Class
+
+Defines the interface and shared utilities for AutoML implementations.
+Tracks best model, best score, best params, and maintains a leaderboard.
+"""
+
+from abc import abstractmethod, ABC
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Any, Dict, List, Optional, Union
+
+import numpy as np
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class LeaderboardEntry:
+    # One row in the AutoML leaderboard.
+    model_name: str
+    framework: str
+    score: float
+    params: Dict[str, Any]
+    duration_seconds: float
+    extra: Dict[str, Any] = field(default_factory=dict)
+
+
+class BaseAutoML(ABC):
+    """
+    Abstract base class for AutoML implementations.
+
+    Subclasses must implement:
+    - fit(X, y) -> self
+    - predict(X) -> np.ndarray
+    - predict_proba(X) -> Optional[np.ndarray]
+    - get_best_model() -> Any
+    """
+
+    def __init__(
+        self,
+        task: str = "classification",
+        metric: str = "accuracy",
+        time_budget_minutes: Optional[Union[int, float]] = None,
+        random_state: Optional[int] = 42,
+        tracker: Optional[Any] = None,
+        verbose: bool = True,
+    ) -> None:
+        """
+        Initialize BaseAutoML.
+
+        Args:
+            task: 'classification' or 'regression'
+            metric: Scoring metric (accuracy, f1, roc_auc, etc.)
+            time_budget_minutes: Max time for AutoML run (None = no limit)
+            random_state: Random seed for reproducibility
+            tracker: Optional ExperimentTracker instance
+            verbose: Whether to print progress
+        """
+        self.task = task.lower()
+        self.metric = metric
+        self.time_budget_minutes = time_budget_minutes
+        self.random_state = random_state
+        self.verbose = verbose
+
+        # Optinal ExperimentTracker
+        self.tracker = tracker
+
+        # Time state
+        self._start_time: Optional[datetime] = None
+        self._end_time: Optional[datetime] = None
+
+        # Best model state
+        self.best_model_: Optional[Any] = None
+        self.best_model_name_: Optional[str] = None
+        self.best_score_: Optional[float] = None
+        self.best_params_: Dict[str, Any] = {}
+
+        # Leaderboard
+        self.leaderboard_: List[LeaderboardEntry] = []
+
+        # Fitted flag
+        self.is_fitted_: bool = False
+
+        logger.debug(
+            f"Initialized {self.__class__.__name__}(task={self.task}, "
+            f"metric={self.metric}, time_budget={self.time_budget_minutes})"
+        )
+
+    @abstractmethod
+    def fit(self, X: np.ndarray, y: np.ndarray, **kwargs) -> "BaseAutoML":
+        """
+        Run AutoML search and fit the best model.
+
+        Args:
+            X: Feature matrix
+            y: Target vector
+            **kwargs: Additional arguments
+
+        Returns:
+            self
+        """
+        pass
+
+    @abstractmethod
+    def predict(self, X: np.ndarray) -> np.ndarray:
+        """
+        Predict using the best model.
+
+        Args:
+            X: Feature matrix
+
+        Returns:
+            Predictions array
+        """
+        pass
+
+    @abstractmethod
+    def predict_proba(self, X: np.ndarray) -> Optional[np.ndarray]:
+        """
+        Predict probabilities using the best model.
+
+        Args:
+            X: Feature matrix
+
+        Returns:
+            Probability array or None if not supported
+        """
+        pass
+
+    @abstractmethod
+    def get_best_model(self) -> Any:
+        """
+        Get the best fitted model/trainer.
+
+        Returns:
+            Best model object
+        """
+        pass
+
+    def get_leaderboard(self) -> List[Dict[str, Any]]:
+        """
+        Get leaderboard as list of dicts (JSON-serializable).
+
+        Returns:
+            List of leaderboard entries
+        """
+
+        return [
+            {
+                "rank": i + 1,
+                "model_name": entry.model_name,
+                "framework": entry.framework,
+                "score": round(entry.score, 6),
+                "params": entry.params,
+                "duration_seconds": round(entry.duration_seconds, 2),
+                "extra": entry.extra,
+            }
+            for i, entry in enumerate(self.leaderboard_)
+        ]
+
+    # Get total AutoML run duration in seconds.
+    def get_run_duration_seconds(self) -> Optional[float]:
+        if self._start_time is None:
+            return None
+        end = self._end_time or datetime.now()
+        return (end - self._start_time).total_seconds()
+
+    def set_tracker(self, tracker: Any) -> None:
+        # Attach an ExperimentTracker after initialization.
+        self.tracker = tracker
+
+    # Time Utilities
+
+    def _start_timer(self) -> None:
+        # Start the run timer.
+        self._start_time = datetime.now()
+        self._end_time = None
+
+    def _end_timer(self) -> None:
+        # End the run timer
+        self._end_time = datetime.now()
+
+    def _time_budget_seconds(self) -> Optional[float]:
+        # Get time budget in seconds
+        if self.time_budget_minutes is None:
+            return None
+        return self.time_budget_minutes * 60.0
+
+    def _elapsed_seconds(self) -> float:
+        # Get elapsed time since start.
+        if self._start_time is None:
+            return 0.0
+        return (datetime.now() - self._start_time).total_seconds()
+
+    def _remaining_seconds(self) -> Optional[float]:
+        # Get remaining time budget in seconds.
+        budget = self._time_budget_seconds()
+        if budget is None:
+            return None
+        return max(0.0, budget - self._elapsed_seconds())
+
+    def _time_budget_exceeded(self) -> bool:
+        # Check if the time budget is exceeded.
+        budget = self._time_budget_seconds()
+        if budget is None:
+            return False
+        return self._elapsed_seconds() >= budget
+
+    #  Tracker Utilities
+
+    def _maybe_log_params(self, params: Dict[str, Any]) -> None:
+        # Log params to tracker if available.
+        if self.tracker is None:
+            return
+        try:
+            self.tracker.log_params(params)
+        except Exception as e:
+            logger.debug(f"Tracker log_params failed: {e}")
+
+    def _maybe_log_metrics(self, metrics: Dict[str, Any], prefix: str = "") -> None:
+        # Log metrics to tracker if available
+        if self.tracker is None:
+            return
+        try:
+            clean: Dict[str, float] = {}
+            for k, v in metrics.items():
+                if isinstance(v, (int, float, np.floating, np.integer)):
+                    clean[k] = float(v)
+            self.tracker.log_metrics(clean, prefix=prefix)
+        except Exception as e:
+            logger.debug(f"Tracker log_metrics failed: {e}")
+
+    # Leaderboard Utilities
+    def _add_leaderboard_entry(
+        self,
+        model_name: str,
+        framework: str,
+        score: float,
+        params: Dict[str, Any],
+        duration_seconds: float,
+        extra: Optional[Dict[str, Any]] = None,
+    ) -> None:
+        # Add an entry to the leaderboard and keep sorted.
+        entry = LeaderboardEntry(
+            model_name=model_name,
+            framework=framework,
+            score=float(score),
+            params=params or {},
+            duration_seconds=float(duration_seconds),
+            extra=extra or {},
+        )
+        self.leaderboard_.append(entry)
+        # Sort by score descending (best first)
+        self.leaderboard_.sort(key=lambda e: e.score, reverse=True)
+
+    def _update_best_if_improved(
+        self,
+        model_name: str,
+        model_obj: Any,
+        score: float,
+        params: Dict[str, Any],
+    ) -> bool:
+        """
+        Update best model if score improves.
+
+        Returns:
+            True if best was updated, False otherwise
+        """
+
+        if self.best_score_ is None or score > self.best_score_:
+            self.best_score_ = float(score)
+            self.best_model_ = model_obj
+            self.best_model_name_ = model_name
+            self.best_params_ = params if params is not None else {}
+            logger.info(f"New best model: {model_name} with score {score:.4f}")
+            return True
+        return False
+
+    # Validation Utilities
+
+    def _validate_inputs(self, X: np.ndarray, y: np.ndarray) -> None:
+        # Validate input arrays.
+        if X is None or y is None:
+            raise ValueError("X and y must not be None")
+        if not isinstance(X, np.ndarray):
+            raise TypeError(f"X must be np.ndarray, got {type(X)}")
+        if not isinstance(y, np.ndarray):
+            raise TypeError(f"y must be np.ndarray, got {type(y)}")
+        if X.shape[0] != y.shape[0]:
+            raise ValueError(f"X and y must have same n_samples: {X.shape[0]} vs {y.shape[0]}")
+
+    def _check_is_fitted(self) -> None:
+        # Raise error if not fitted.
+        if not self.is_fitted_:
+            raise RuntimeError(f"{self.__class__.__name__} is not fitted. Call fit() first.")
+
+    def __repr__(self) -> str:
+        return (
+            f"{self.__class__.__name__}("
+            f"task={self.task}, metric={self.metric}, "
+            f"time_budget={self.time_budget_minutes}, "
+            f"best_model={self.best_model_name_}, "
+            f"best_score={self.best_score_})"
+        )