diff --git a/src/cli_explain_fix/parser.py b/src/cli_explain_fix/parser.py
new file mode 100644
index 0000000..e86ec91
--- /dev/null
+++ b/src/cli_explain_fix/parser.py
@@ -0,0 +1,248 @@
+"""Error pattern parsing module."""
+
+import re
+from dataclasses import dataclass, field
+from typing import Optional, List, Dict, Any
+
+
+@dataclass
+class ParsedError:
+    """Container for parsed error information."""
+    error_type: str
+    message: str
+    language: str
+    file_name: Optional[str] = None
+    line_number: Optional[int] = None
+    column_number: Optional[int] = None
+    stack_frames: List[Dict[str, Any]] = field(default_factory=list)
+    raw_input: str = ""
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary for JSON output."""
+        return {
+            'error_type': self.error_type,
+            'message': self.message,
+            'language': self.language,
+            'file_name': self.file_name,
+            'line_number': self.line_number,
+            'column_number': self.column_number,
+            'stack_frames': self.stack_frames,
+        }
+
+
+class ErrorParser:
+    """Parser for various error formats and languages."""
+
+    PYTHON_TRACEBACK_PATTERN = re.compile(
+        r'^(?:Traceback \(most recent call last\):\n)?'
+        r'(?P<frame>  File "([^"]+)", line (?P<line>\d+), in .+\n'
+        r'    .+\n)?'
+        r'(?P<exception>[A-Za-z]+Error): (?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    PYTHON_SIMPLE_PATTERN = re.compile(
+        r'^(?P<exception>[A-Za-z]+Error): (?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    JS_ERROR_PATTERN = re.compile(
+        r'^(?:TypeError|ReferenceError|SyntaxError|RangeError|Error): (?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    GO_PANIC_PATTERN = re.compile(
+        r'^panic: (?P<message>.+)$\n'
+        r'(?:\n.*goroutine \d+ \[.*\]:\n)?'
+        r'(?P<frame>.*\n)*',
+        re.MULTILINE
+    )
+
+    RUST_PANIC_PATTERN = re.compile(
+        r'^thread .* panicked at .*"(?P<message>.+)"',
+        re.MULTILINE
+    )
+
+    GENERIC_CLI_PATTERN = re.compile(
+        r'^(?:error|Error|ERROR)(?::?)\s*(?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    JSON_PARSE_PATTERN = re.compile(
+        r'^(?:JSONDecodeError|Expecting value|syntax error): (?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    YAML_PARSE_PATTERN = re.compile(
+        r'^(?:YAMLError|ParserError|ScannerError): (?P<message>.+)$',
+        re.MULTILINE
+    )
+
+    def __init__(self):
+        self.language_patterns = {
+            'python': [
+                (self.PYTHON_TRACEBACK_PATTERN, self._parse_python_traceback),
+                (self.PYTHON_SIMPLE_PATTERN, self._parse_python_simple),
+            ],
+            'javascript': [
+                (self.JS_ERROR_PATTERN, self._parse_js_error),
+            ],
+            'go': [
+                (self.GO_PANIC_PATTERN, self._parse_go_panic),
+            ],
+            'rust': [
+                (self.RUST_PANIC_PATTERN, self._parse_rust_panic),
+            ],
+            'json': [
+                (self.JSON_PARSE_PATTERN, self._parse_json_error),
+            ],
+            'yaml': [
+                (self.YAML_PARSE_PATTERN, self._parse_yaml_error),
+            ],
+        }
+
+    def detect_language(self, input_text: str) -> str:
+        """Detect the programming language from error format."""
+        text = input_text.strip()
+
+        if 'Traceback (most recent call last):' in text or 'File "' in text:
+            return 'python'
+        if re.search(r'File ".+\.py", line \d+', text):
+            return 'python'
+        if re.search(r'panic:', text):
+            return 'go'
+        if re.search(r'thread .* panicked at', text):
+            return 'rust'
+        if re.search(r'goroutine \d+', text):
+            return 'go'
+        if re.search(r'(JSONDecodeError|Expecting value)', text):
+            return 'json'
+        if re.search(r'(YAMLError|ParserError|ScannerError)', text):
+            return 'yaml'
+        if re.search(r'^(TypeError|ReferenceError|SyntaxError|RangeError):', text, re.MULTILINE):
+            return 'javascript'
+        if re.search(r'[A-Za-z]+Error:', text):
+            return 'python'
+        if re.search(r'^error:|^Error:|^ERROR:', text, re.MULTILINE):
+            return 'cli'
+
+        return 'unknown'
+
+    def parse(self, input_text: str, language: Optional[str] = None) -> ParsedError:
+        """Parse error text and extract structured information."""
+        if language is None:
+            language = self.detect_language(input_text)
+
+        detected_language = language
+
+        if language in self.language_patterns:
+            for pattern, parser in self.language_patterns[language]:
+                match = pattern.search(input_text)
+                if match:
+                    return parser(match, input_text, detected_language)
+
+        if language == 'cli':
+            match = self.GENERIC_CLI_PATTERN.search(input_text)
+            if match:
+                return ParsedError(
+                    error_type='GenericError',
+                    message=match.group('message').strip(),
+                    language='cli',
+                    raw_input=input_text,
+                )
+
+        return ParsedError(
+            error_type='UnknownError',
+            message=input_text.strip() if input_text.strip() else 'Unknown error occurred',
+            language=detected_language,
+            raw_input=input_text,
+        )
+
+    def _parse_python_traceback(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse Python traceback format."""
+        exception = match.group('exception')
+        message = match.group('message')
+
+        stack_frames = []
+        frame_match = re.findall(
+            r'  File "([^"]+)", line (\d+), in ([^\n]+)\n    ([^\n]+)',
+            input_text
+        )
+        for frame in frame_match:
+            stack_frames.append({
+                'file': frame[0],
+                'line': int(frame[1]) if frame[1].isdigit() else None,
+                'function': frame[2],
+                'code': frame[3],
+            })
+
+        file_name = None
+        line_number = None
+        if stack_frames:
+            last_frame = stack_frames[-1]
+            file_name = last_frame.get('file')
+            line_number = last_frame.get('line')
+
+        return ParsedError(
+            error_type=exception,
+            message=message,
+            language=language,
+            file_name=file_name,
+            line_number=line_number,
+            stack_frames=stack_frames,
+            raw_input=input_text,
+        )
+
+    def _parse_python_simple(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse simple Python error format."""
+        return ParsedError(
+            error_type=match.group('exception'),
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )
+
+    def _parse_js_error(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse JavaScript error format."""
+        return ParsedError(
+            error_type=match.group(0).split(':')[0] if ':' in match.group(0) else 'Error',
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )
+
+    def _parse_go_panic(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse Go panic format."""
+        return ParsedError(
+            error_type='panic',
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )
+
+    def _parse_rust_panic(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse Rust panic format."""
+        return ParsedError(
+            error_type='panic',
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )
+
+    def _parse_json_error(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse JSON parse error format."""
+        return ParsedError(
+            error_type='JSONParseError',
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )
+
+    def _parse_yaml_error(self, match: re.Match, input_text: str, language: str) -> ParsedError:
+        """Parse YAML parse error format."""
+        return ParsedError(
+            error_type='YAMLParseError',
+            message=match.group('message'),
+            language=language,
+            raw_input=input_text,
+        )