diff --git a/git_commit_ai/core/ollama_client.py b/git_commit_ai/core/ollama_client.py
new file mode 100644
index 0000000..e2c4e3f
--- /dev/null
+++ b/git_commit_ai/core/ollama_client.py
@@ -0,0 +1,136 @@
+"""Ollama API client for Git Commit AI."""
+
+import hashlib
+import logging
+from typing import Any, Optional
+
+import ollama
+import requests
+
+from git_commit_ai.core.config import Config, get_config
+
+logger = logging.getLogger(__name__)
+
+
+class OllamaClient:
+    """Client for communicating with Ollama API."""
+
+    def __init__(self, config: Optional[Config] = None):
+        self.config = config or get_config()
+        self._model: str = self.config.ollama_model
+        self._base_url: str = self.config.ollama_base_url
+        self._timeout: int = self.config.ollama_timeout
+
+    @property
+    def model(self) -> str:
+        return self._model
+
+    @model.setter
+    def model(self, value: str) -> None:
+        self._model = value
+
+    @property
+    def base_url(self) -> str:
+        return self._base_url
+
+    @base_url.setter
+    def base_url(self, value: str) -> None:
+        self._base_url = value
+
+    def is_available(self) -> bool:
+        try:
+            response = requests.get(f"{self._base_url}/api/tags", timeout=10)
+            return response.status_code == 200
+        except requests.RequestException:
+            return False
+
+    def list_models(self) -> list[dict[str, Any]]:
+        try:
+            response = requests.get(f"{self._base_url}/api/tags", timeout=self._timeout)
+            if response.status_code == 200:
+                data = response.json()
+                return data.get("models", [])
+            return []
+        except requests.RequestException as e:
+            logger.error(f"Failed to list models: {e}")
+            return []
+
+    def check_model_exists(self) -> bool:
+        models = self.list_models()
+        model_names = [m.get("name", "") for m in models]
+        return any(self._model in name for name in model_names)
+
+    def pull_model(self, model: Optional[str] = None) -> bool:
+        model = model or self._model
+        try:
+            client = ollama.Client(host=self._base_url)
+            client.pull(model)
+            return True
+        except Exception as e:
+            logger.error(f"Failed to pull model {model}: {e}")
+            return False
+
+    def generate(self, prompt: str, system: Optional[str] = None, model: Optional[str] = None, num_predict: int = 200, temperature: float = 0.7) -> str:
+        model = model or self._model
+        try:
+            client = ollama.Client(host=self._base_url)
+            response = client.generate(
+                model=model, prompt=prompt, system=system,
+                options={"num_predict": num_predict, "temperature": temperature}
+            )
+            return response.get("response", "")
+        except Exception as e:
+            logger.error(f"Failed to generate response: {e}")
+            raise OllamaError(f"Failed to generate response: {e}") from e
+
+    def generate_commit_message(self, diff: str, context: Optional[str] = None, conventional: bool = False, model: Optional[str] = None) -> str:
+        from git_commit_ai.prompts import PromptBuilder
+
+        prompt_builder = PromptBuilder(self.config)
+        prompt = prompt_builder.build_prompt(diff, context, conventional)
+        system_prompt = prompt_builder.get_system_prompt(conventional)
+
+        response = self.generate(
+            prompt=prompt, system=system_prompt, model=model,
+            num_predict=self.config.max_message_length + 50,
+            temperature=0.7 if not conventional else 0.5,
+        )
+
+        return self._parse_commit_message(response)
+
+    def _parse_commit_message(self, response: str) -> str:
+        message = response.strip()
+
+        if message.startswith("```"):
+            lines = message.split("\n")
+            if len(lines) >= 3:
+                content = "\n".join(lines[1:-1])
+                if content.strip().startswith("git commit"):
+                    content = content.replace("git commit -m ", "").strip()
+                    if content.startswith('"') and content.endswith('"'):
+                        content = content[1:-1]
+                    return content.strip()
+
+        if message.startswith('"') and message.endswith('"'):
+            message = message[1:-1]
+
+        message = message.strip()
+
+        max_length = self.config.max_message_length
+        if len(message) > max_length:
+            message = message[:max_length].rsplit(" ", 1)[0]
+
+        return message
+
+
+class OllamaError(Exception):
+    """Exception raised for Ollama-related errors."""
+    pass
+
+
+def generate_diff_hash(diff: str) -> str:
+    return hashlib.md5(diff.encode()).hexdigest()
+
+
+def get_client(config: Optional[Config] = None) -> OllamaClient:
+    return OllamaClient(config)