diff --git a/app/src/git_commit_generator/changelog_generator.py b/app/src/git_commit_generator/changelog_generator.py
new file mode 100644
index 0000000..4de636a
--- /dev/null
+++ b/app/src/git_commit_generator/changelog_generator.py
@@ -0,0 +1,170 @@
+"""Changelog generation from git history."""
+from datetime import datetime
+from typing import Optional
+
+from git_commit_generator.config import Config, get_config
+from git_commit_generator.git_utils import GitUtils, get_git_utils
+from git_commit_generator.ollama_client import OllamaClient, get_ollama_client
+
+
+class ChangelogGenerator:
+    """Generates CHANGELOG.md from git history."""
+
+    CHANGE_TYPES = {
+        "feat": ("Features", "green"),
+        "fix": ("Bug Fixes", "red"),
+        "docs": ("Documentation", "blue"),
+        "style": ("Code Style", "gray"),
+        "refactor": ("Refactoring", "magenta"),
+        "perf": ("Performance", "yellow"),
+        "test": ("Tests", "cyan"),
+        "build": ("Build System", "white"),
+        "ci": ("CI/CD", "white"),
+        "chore": ("Maintenance", "gray"),
+        "revert": ("Reverts", "red"),
+    }
+
+    def __init__(
+        self,
+        config: Optional[Config] = None,
+        ollama_client: Optional[OllamaClient] = None,
+        repo_path: Optional[str] = None,
+    ):
+        """Initialize changelog generator."""
+        self.config = config or get_config()
+        self.ollama_client = ollama_client or OllamaClient(
+            host=self.config.ollama_host,
+            model=self.config.ollama_model
+        )
+        self.git_utils = GitUtils(repo_path)
+
+    def generate(
+        self,
+        since: Optional[str] = None,
+        limit: int = 50,
+        output_path: Optional[str] = None,
+    ) -> str:
+        """Generate a changelog."""
+        commits = self.git_utils.get_commit_history(since=since, limit=limit)
+
+        if not commits:
+            raise ValueError("No commits found in repository.")
+
+        prompt = self.config.read_prompt("changelog.txt")
+        if not prompt:
+            prompt = self._get_default_changelog_prompt()
+
+        commits_text = self._format_commits_for_prompt(commits)
+        changelog = self.ollama_client.generate_changelog(
+            commits=commits_text,
+            prompt=prompt,
+            model=self.config.ollama_model,
+        )
+
+        changelog = self._clean_changelog(changelog)
+
+        if output_path:
+            self._write_changelog(output_path, changelog)
+
+        return changelog
+
+    def _get_default_changelog_prompt(self) -> str:
+        """Get default changelog prompt."""
+        return """Generate a changelog in markdown format from the following commits.
+Group by type (feat, fix, docs, etc.) and format properly."""
+
+    def _format_commits_for_prompt(self, commits: list[dict]) -> str:
+        """Format commits for the LLM prompt."""
+        lines = []
+        for commit in commits:
+            lines.append(
+                f"[{commit['hash']}] {commit['message']} ({commit['author']}, {commit['date']})"
+            )
+        return "\n".join(lines)
+
+    def _clean_changelog(self, changelog: str) -> str:
+        """Clean and normalize changelog."""
+        lines = changelog.strip().split("\n")
+
+        cleaned_lines = []
+        for line in lines:
+            line = line.strip()
+            if line and not line.startswith("```"):
+                cleaned_lines.append(line)
+
+        return "\n".join(cleaned_lines)
+
+    def _write_changelog(self, path: str, changelog: str) -> None:
+        """Write changelog to file."""
+        with open(path, "w") as f:
+            f.write(f"# Changelog\n\nGenerated on {datetime.now().isoformat()}\n\n")
+            f.write(changelog)
+
+    def generate_simple(
+        self,
+        since: Optional[str] = None,
+        limit: int = 50,
+        output_path: Optional[str] = None,
+    ) -> str:
+        """Generate a simple changelog without LLM."""
+        commits = self.git_utils.get_conventional_commits(since=since, limit=limit)
+
+        if not commits:
+            raise ValueError("No conventional commits found in repository.")
+
+        grouped = self._group_commits_by_type(commits)
+
+        changelog = self._format_simple_changelog(grouped)
+
+        if output_path:
+            self._write_changelog(output_path, changelog)
+
+        return changelog
+
+    def _group_commits_by_type(self, commits: list[dict]) -> dict:
+        """Group commits by their type."""
+        grouped = {}
+        for commit in commits:
+            commit_type = commit.get("type", "chore")
+            if commit_type not in grouped:
+                grouped[commit_type] = []
+            grouped[commit_type].append(commit)
+        return grouped
+
+    def _format_simple_changelog(self, grouped: dict) -> str:
+        """Format grouped commits into markdown changelog."""
+        lines = ["# Changelog\n"]
+
+        type_order = [
+            "feat", "fix", "perf", "refactor", "docs",
+            "style", "test", "build", "ci", "chore", "revert"
+        ]
+
+        for commit_type in type_order:
+            if commit_type in grouped:
+                type_name, _ = self.CHANGE_TYPES.get(
+                    commit_type, (commit_type.title(), "white")
+                )
+                lines.append(f"\n## {type_name}\n")
+                for commit in grouped[commit_type]:
+                    scope = commit.get("scope", "")
+                    description = commit.get("description", "")
+                    if scope:
+                        lines.append(f"- **{commit_type}({scope}):** {description}")
+                    else:
+                        lines.append(f"- **{commit_type}:** {description}")
+
+        return "\n".join(lines)
+
+
+def get_changelog_generator(
+    config: Optional[Config] = None,
+    ollama_client: Optional[OllamaClient] = None,
+    repo_path: Optional[str] = None,
+) -> ChangelogGenerator:
+    """Get ChangelogGenerator instance."""
+    return ChangelogGenerator(
+        config=config,
+        ollama_client=ollama_client,
+        repo_path=repo_path,
+    )