diff --git a/README.md b/README.md
index 6d2a502..e763772 100644
--- a/README.md
+++ b/README.md
@@ -122,7 +122,7 @@ For Anthropic models above version 3 (i.e. Sonnet 3.5, Haiku 3.5, and Opus 3), w
 Units denominated in USD. All prices can be located in `model_prices.json`.
 
 
-* Prices last updated Jan 30, 2024 from [LiteLLM's cost dictionary](https://github.com/BerriAI/litellm/blob/main/model_prices_and_context_window.json)
+* Prices last updated Jan 30, 2024 from [OpenRouter's model list](https://openrouter.ai/docs/api-reference/list-available-models). Use the optional `OPENROUTER_API_KEY` environment variable if authentication is needed when refreshing prices programmatically.
 
 | Model Name                                                            | Prompt Cost (USD) per 1M tokens   | Completion Cost (USD) per 1M tokens   | Max Prompt Tokens   |   Max Output Tokens |
 |:----------------------------------------------------------------------|:----------------------------------|:--------------------------------------|:--------------------|--------------------:|
diff --git a/pyproject.toml b/pyproject.toml
index 9ce218b..8d88ed7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ tokencost = ["model_prices.json"]
 
 [project]
 name = "tokencost"
-version = "0.1.23"
+version = "0.1.24"
 authors = [
   { name = "Trisha Pan", email = "trishaepan@gmail.com" },
   { name = "Alex Reibman", email = "areibman@gmail.com" },
diff --git a/tokencost/constants.py b/tokencost/constants.py
index 619ef5a..ec41941 100644
--- a/tokencost/constants.py
+++ b/tokencost/constants.py
@@ -24,17 +24,26 @@
 # Each completion token costs __ USD per token.
 # Max prompt limit of each model is __ tokens.
 
-PRICES_URL = "https://raw.githubusercontent.com/BerriAI/litellm/main/model_prices_and_context_window.json"
+# Endpoint to fetch the latest model information from OpenRouter.
+# ``OPENROUTER_API_KEY`` may optionally be set for authentication. The static
+# ``model_prices.json`` data is used as a fallback when the request fails.
+PRICES_URL = "https://openrouter.ai/api/v1/models"
 
 
 async def fetch_costs():
-    """Fetch the latest token costs from the LiteLLM cost tracker asynchronously.
+    """Fetch the latest token costs from OpenRouter asynchronously.
+
     Returns:
         dict: The token costs for each model.
     Raises:
         Exception: If the request fails.
     """
-    async with aiohttp.ClientSession(trust_env=True) as session:
+    headers = {}
+    api_key = os.getenv("OPENROUTER_API_KEY")
+    if api_key:
+        headers["Authorization"] = f"Bearer {api_key}"
+
+    async with aiohttp.ClientSession(headers=headers, trust_env=True) as session:
         async with session.get(PRICES_URL) as response:
             if response.status == 200:
                 return await response.json(content_type=None)
@@ -45,7 +54,7 @@ async def fetch_costs():
 
 
 async def update_token_costs():
-    """Update the TOKEN_COSTS dictionary with the latest costs from the LiteLLM cost tracker asynchronously."""
+    """Update :data:`TOKEN_COSTS` with the latest prices from OpenRouter."""
     global TOKEN_COSTS
     try:
         fetched_costs = await fetch_costs()
diff --git a/update_prices.py b/update_prices.py
index b2a44c0..9959081 100644
--- a/update_prices.py
+++ b/update_prices.py
@@ -4,7 +4,7 @@
 import json
 import re
 
-# Update model_prices.json with the latest costs from the LiteLLM cost tracker
+# Update model_prices.json with the latest costs from OpenRouter
 print("Fetching latest prices...")
 tokencost.refresh_prices(write_file=False)