diff --git a/loglens/parsers/base.py b/loglens/parsers/base.py
new file mode 100644
index 0000000..0dabeb9
--- /dev/null
+++ b/loglens/parsers/base.py
@@ -0,0 +1,91 @@
+"""Base parser class and data structures."""
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Any, Dict, List, Optional
+from enum import Enum
+
+
+class LogFormat(Enum):
+    """Supported log formats."""
+    JSON = "json"
+    SYSLOG = "syslog"
+    APACHE = "apache"
+    UNKNOWN = "unknown"
+
+
+@dataclass
+class ParsedLogEntry:
+    """Represents a parsed log entry."""
+    raw_line: str
+    timestamp: Optional[datetime] = None
+    level: Optional[str] = None
+    message: str = ""
+    source: Optional[str] = None
+    host: Optional[str] = None
+    facility: Optional[str] = None
+    severity: Optional[str] = None
+    logger: Optional[str] = None
+    extra: Dict[str, Any] = field(default_factory=dict)
+    line_number: int = 0
+    error_pattern: Optional[str] = None
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary."""
+        result = {
+            "raw_line": self.raw_line,
+            "message": self.message,
+            "line_number": self.line_number,
+        }
+        if self.timestamp:
+            result["timestamp"] = self.timestamp.isoformat()
+        if self.level:
+            result["level"] = self.level
+        if self.source:
+            result["source"] = self.source
+        if self.host:
+            result["host"] = self.host
+        if self.facility:
+            result["facility"] = self.facility
+        if self.severity:
+            result["severity"] = self.severity
+        if self.logger:
+            result["logger"] = self.logger
+        if self.extra:
+            result["extra"] = self.extra
+        if self.error_pattern:
+            result["error_pattern"] = self.error_pattern
+        return result
+
+
+class LogParser(ABC):
+    """Abstract base class for log parsers."""
+
+    format_name: str = "base"
+
+    @abstractmethod
+    def parse(self, line: str, line_number: int = 0) -> Optional[ParsedLogEntry]:
+        """Parse a single log line."""
+        pass
+
+    @abstractmethod
+    def can_parse(self, line: str) -> bool:
+        """Check if this parser can handle the given line."""
+        pass
+
+    def parse_batch(self, lines: List[str]) -> List[ParsedLogEntry]:
+        """Parse multiple lines."""
+        results = []
+        for i, line in enumerate(lines, 1):
+            try:
+                entry = self.parse(line, i)
+                if entry:
+                    results.append(entry)
+            except Exception:
+                results.append(ParsedLogEntry(
+                    raw_line=line,
+                    message="Parse error",
+                    line_number=i
+                ))
+        return results