diff --git a/.env.example b/.env.example
index bf31904..798ad8a 100644
--- a/.env.example
+++ b/.env.example
@@ -5,17 +5,17 @@ GEMINI_API_KEY="your-google-ai-studio-key"
 
 # Optional: Provider Preference and Model Mapping
 # Controls which provider (google or openai) is preferred for mapping haiku/sonnet.
-# Defaults to google if not set.
-PREFERRED_PROVIDER="google"
+# Defaults to openai if not set.
+PREFERRED_PROVIDER="openai"
 
 # Optional: Specify the exact models to map haiku/sonnet to.
 # If PREFERRED_PROVIDER=google, these MUST be valid Gemini model names known to the server.
 # Defaults to gemini-2.5-pro-preview-03-25 and gemini-2.0-flash if PREFERRED_PROVIDER=google.
-# Defaults to gpt-4o and gpt-4o-mini if PREFERRED_PROVIDER=openai.
-# BIG_MODEL="gemini-2.5-pro-preview-03-25"
-# SMALL_MODEL="gemini-2.0-flash"
+# Defaults to gpt-4.1 and gpt-4.1-mini if PREFERRED_PROVIDER=openai.
+# BIG_MODEL="gpt-4.1"
+# SMALL_MODEL="gpt-4.1-mini"
 
-# Example OpenAI mapping:
-# PREFERRED_PROVIDER="openai"
-# BIG_MODEL="gpt-4o"
-# SMALL_MODEL="gpt-4o-mini" 
\ No newline at end of file
+# Example Google mapping:
+# PREFERRED_PROVIDER="google"
+# BIG_MODEL="gemini-2.5-pro-preview-03-25"
+# SMALL_MODEL="gemini-2.0-flash" 
\ No newline at end of file
diff --git a/README.md b/README.md
index 5a8ba12..3dbbc89 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ A proxy server that lets you use Anthropic clients with Gemini or OpenAI models
 ### Prerequisites
 
 - OpenAI API key 🔑
-- Google AI Studio (Gemini) API key (if using default provider) 🔑
+- Google AI Studio (Gemini) API key (if using Google provider) 🔑
 - [uv](https://github.com/astral-sh/uv) installed.
 
 ### Setup 🛠️
@@ -37,15 +37,15 @@ A proxy server that lets you use Anthropic clients with Gemini or OpenAI models
    Edit `.env` and fill in your API keys and model configurations:
 
    *   `ANTHROPIC_API_KEY`: (Optional) Needed only if proxying *to* Anthropic models.
-   *   `OPENAI_API_KEY`: Your OpenAI API key (Required if using OpenAI models as fallback or primary).
-   *   `GEMINI_API_KEY`: Your Google AI Studio (Gemini) API key (Required if using the default Gemini preference).
-   *   `PREFERRED_PROVIDER` (Optional): Set to `google` (default) or `openai`. This determines the primary backend for mapping `haiku`/`sonnet`.
-   *   `BIG_MODEL` (Optional): The model to map `sonnet` requests to. Defaults to `gemini-2.5-pro-preview-03-25` (if `PREFERRED_PROVIDER=google` and model is known) or `gpt-4o`.
-   *   `SMALL_MODEL` (Optional): The model to map `haiku` requests to. Defaults to `gemini-2.0-flash` (if `PREFERRED_PROVIDER=google` and model is known) or `gpt-4o-mini`.
+   *   `OPENAI_API_KEY`: Your OpenAI API key (Required if using the default OpenAI preference or as fallback).
+   *   `GEMINI_API_KEY`: Your Google AI Studio (Gemini) API key (Required if PREFERRED_PROVIDER=google).
+   *   `PREFERRED_PROVIDER` (Optional): Set to `openai` (default) or `google`. This determines the primary backend for mapping `haiku`/`sonnet`.
+   *   `BIG_MODEL` (Optional): The model to map `sonnet` requests to. Defaults to `gpt-4.1` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.5-pro-preview-03-25`.
+   *   `SMALL_MODEL` (Optional): The model to map `haiku` requests to. Defaults to `gpt-4.1-mini` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.0-flash`.
 
    **Mapping Logic:**
-   - If `PREFERRED_PROVIDER=google` (default), `haiku`/`sonnet` map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `gemini/` *if* those models are in the server's known `GEMINI_MODELS` list.
-   - Otherwise (if `PREFERRED_PROVIDER=openai` or the specified Google model isn't known), they map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `openai/`.
+   - If `PREFERRED_PROVIDER=openai` (default), `haiku`/`sonnet` map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `openai/`.
+   - If `PREFERRED_PROVIDER=google`, `haiku`/`sonnet` map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `gemini/` *if* those models are in the server's known `GEMINI_MODELS` list (otherwise falls back to OpenAI mapping).
 
 4. **Run the server**:
    ```bash
@@ -90,6 +90,8 @@ The following OpenAI models are supported with automatic `openai/` prefix handli
 - chatgpt-4o-latest
 - gpt-4o-mini
 - gpt-4o-mini-audio-preview
+- gpt-4.1
+- gpt-4.1-mini
 
 #### Gemini Models
 The following Gemini models are supported with automatic `gemini/` prefix handling:
@@ -109,33 +111,34 @@ For example:
 
 ### Customizing Model Mapping
 
-You can customize which models are used via environment variables:
+Control the mapping using environment variables in your `.env` file or directly:
 
-- `BIG_MODEL`: The model to use for Claude Sonnet models (default: "gpt-4o")
-- `SMALL_MODEL`: The model to use for Claude Haiku models (default: "gpt-4o-mini")
-
-Add these to your `.env` file to customize:
-```
-OPENAI_API_KEY=your-openai-key
-# For OpenAI models (default)
-BIG_MODEL=gpt-4o
-SMALL_MODEL=gpt-4o-mini
-
-# For Gemini models
-# BIG_MODEL=gemini-2.5-pro-preview-03-25
-# SMALL_MODEL=gemini-2.0-flash
+**Example 1: Default (Use OpenAI)**
+No changes needed in `.env` beyond API keys, or ensure:
+```dotenv
+OPENAI_API_KEY="your-openai-key"
+GEMINI_API_KEY="your-google-key" # Needed if PREFERRED_PROVIDER=google
+# PREFERRED_PROVIDER="openai" # Optional, it's the default
+# BIG_MODEL="gpt-4.1" # Optional, it's the default
+# SMALL_MODEL="gpt-4.1-mini" # Optional, it's the default
 ```
 
-Or set them directly when running the server:
-```bash
-# Using OpenAI models (with uv)
-BIG_MODEL=gpt-4o SMALL_MODEL=gpt-4o-mini uv run uvicorn server:app --host 0.0.0.0 --port 8082
+**Example 2: Prefer Google**
+```dotenv
+GEMINI_API_KEY="your-google-key"
+OPENAI_API_KEY="your-openai-key" # Needed for fallback
+PREFERRED_PROVIDER="google"
+# BIG_MODEL="gemini-2.5-pro-preview-03-25" # Optional, it's the default for Google pref
+# SMALL_MODEL="gemini-2.0-flash" # Optional, it's the default for Google pref
+```
 
-# Using Gemini models (with uv)
-BIG_MODEL=gemini-2.5-pro-preview-03-25 SMALL_MODEL=gemini-2.0-flash uv run uvicorn server:app --host 0.0.0.0 --port 8082
-
-# Mix and match (with uv)
-BIG_MODEL=gemini-2.5-pro-preview-03-25 SMALL_MODEL=gpt-4o-mini uv run uvicorn server:app --host 0.0.0.0 --port 8082
+**Example 3: Use Specific OpenAI Models**
+```dotenv
+OPENAI_API_KEY="your-openai-key"
+GEMINI_API_KEY="your-google-key"
+PREFERRED_PROVIDER="openai"
+BIG_MODEL="gpt-4o" # Example specific model
+SMALL_MODEL="gpt-4o-mini" # Example specific model
 ```
 
 ## How It Works 🧩
diff --git a/server.py b/server.py
index 51f6daf..f4966b2 100644
--- a/server.py
+++ b/server.py
@@ -82,13 +82,13 @@ ANTHROPIC_API_KEY = os.environ.get("ANTHROPIC_API_KEY")
 OPENAI_API_KEY = os.environ.get("OPENAI_API_KEY")
 GEMINI_API_KEY = os.environ.get("GEMINI_API_KEY")
 
-# Get preferred provider (default to google)
-PREFERRED_PROVIDER = os.environ.get("PREFERRED_PROVIDER", "google").lower()
+# Get preferred provider (default to openai)
+PREFERRED_PROVIDER = os.environ.get("PREFERRED_PROVIDER", "openai").lower()
 
 # Get model mapping configuration from environment
-# Default to latest Gemini models if not set
-BIG_MODEL = os.environ.get("BIG_MODEL", "gemini-2.5-pro-preview-03-25")
-SMALL_MODEL = os.environ.get("SMALL_MODEL", "gemini-2.0-flash")
+# Default to latest OpenAI models if not set
+BIG_MODEL = os.environ.get("BIG_MODEL", "gpt-4.1")
+SMALL_MODEL = os.environ.get("SMALL_MODEL", "gpt-4.1-mini")
 
 # List of OpenAI models
 OPENAI_MODELS = [
@@ -101,7 +101,9 @@ OPENAI_MODELS = [
     "gpt-4o-audio-preview",
     "chatgpt-4o-latest",
     "gpt-4o-mini",
-    "gpt-4o-mini-audio-preview"
+    "gpt-4o-mini-audio-preview",
+    "gpt-4.1",  # Added default big model
+    "gpt-4.1-mini" # Added default small model
 ]
 
 # List of Gemini models