diff --git a/src/utils/date_utils.py b/src/utils/date_utils.py
new file mode 100644
index 0000000..30d7ed4
--- /dev/null
+++ b/src/utils/date_utils.py
@@ -0,0 +1,65 @@
+from datetime import datetime, timedelta
+from typing import Tuple
+
+
+def get_date_range(days: int) -> Tuple[datetime, datetime]:
+    """Get date range for the last N days."""
+    end_date = datetime.now()
+    start_date = end_date - timedelta(days=days)
+    return start_date, end_date
+
+
+def parse_timestamp(timestamp_str: str) -> datetime:
+    """Parse a timestamp string to datetime."""
+    formats = [
+        "%Y-%m-%d %H:%M:%S",
+        "%Y-%m-%dT%H:%M:%S",
+        "%Y-%m-%d %H:%M:%S%z",
+        "%Y-%m-%dT%H:%M:%SZ",
+    ]
+
+    for fmt in formats:
+        try:
+            return datetime.strptime(timestamp_str, fmt)
+        except ValueError:
+            continue
+
+    raise ValueError(f"Cannot parse timestamp: {timestamp_str}")
+
+
+def format_duration(seconds: float) -> str:
+    """Format duration in human-readable format."""
+    if seconds < 60:
+        return f"{seconds:.1f}s"
+    elif seconds < 3600:
+        minutes = seconds / 60
+        return f"{minutes:.1f}m"
+    elif seconds < 86400:
+        hours = seconds / 3600
+        return f"{hours:.1f}h"
+    else:
+        days = seconds / 86400
+        return f"{days:.1f}d"
+
+
+def group_by_period(
+    commits: list,
+    period: str = "day",
+) -> dict:
+    """Group commits by time period."""
+    result = {}
+    for commit in commits:
+        if period == "hour":
+            key = commit.timestamp.strftime("%Y-%m-%d %H:00")
+        elif period == "day":
+            key = commit.timestamp.strftime("%Y-%m-%d")
+        elif period == "week":
+            key = commit.timestamp.strftime("%Y-%W")
+        elif period == "month":
+            key = commit.timestamp.strftime("%Y-%m")
+        else:
+            key = commit.timestamp.strftime("%Y-%m-%d")
+
+        result[key] = result.get(key, 0) + 1
+
+    return result