feat(llm): Add OpenRouter Support (#635)

* Add OpenRouter and docs

* Rename OpenRouter and LiteLLM LlmApiType

Author: par4m

docs/docs/ai/llm.mdx

@@ -175,7 +175,7 @@ litellm --config config.yml
 
 ```python
 cocoindex.LlmSpec(
-    api_type=cocoindex.LlmApiType.LITELLM,
+    api_type=cocoindex.LlmApiType.LITE_LLM,
     model="deepseek-r1", 
     address="http://127.0.0.1:4000", # default url of LiteLLM
 )
@@ -186,3 +186,24 @@ cocoindex.LlmSpec(
 
 You can find the full list of models supported by LiteLLM [here](https://docs.litellm.ai/docs/providers).
 
+### OpenRouter
+
+To use the OpenRouter API, you need to set the environment variable `OPENROUTER_API_KEY`.
+You can generate the API key from [here](https://openrouter.ai/settings/keys).
+
+A spec for OpenRouter looks like this:
+
+<Tabs>
+<TabItem value="python" label="Python" default>
+
+```python
+cocoindex.LlmSpec(
+    api_type=cocoindex.LlmApiType.OPEN_ROUTER,
+    model="deepseek/deepseek-r1:free",
+)
+```
+
+</TabItem>
+</Tabs>
+
+You can find the full list of models supported by OpenRouter [here](https://openrouter.ai/models).

python/cocoindex/llm.py

@@ -9,7 +9,8 @@ class LlmApiType(Enum):
     OLLAMA = "Ollama"
     GEMINI = "Gemini"
     ANTHROPIC = "Anthropic"
-    LITELLM = "LiteLlm"
+    LITE_LLM = "LiteLlm"
+    OPEN_ROUTER = "OpenRouter"
 
 
 @dataclass

src/llm/mod.rs

@@ -14,6 +14,7 @@ pub enum LlmApiType {
     Gemini,
     Anthropic,
     LiteLlm,
+    OpenRouter,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -58,6 +59,7 @@ mod gemini;
 mod ollama;
 mod openai;
 mod litellm;
+mod openrouter;
 
 pub async fn new_llm_generation_client(spec: LlmSpec) -> Result<Box<dyn LlmGenerationClient>> {
     let client = match spec.api_type {
@@ -76,6 +78,11 @@ pub async fn new_llm_generation_client(spec: LlmSpec) -> Result<Box<dyn LlmGener
         LlmApiType::LiteLlm => {
             Box::new(litellm::Client::new_litellm(spec).await?) as Box<dyn LlmGenerationClient>
         }
+        LlmApiType::OpenRouter => {
+            Box::new(openrouter::Client::new_openrouter(spec).await?) as Box<dyn LlmGenerationClient>
+        }
+
+
     };
     Ok(client)
 }

src/llm/openrouter.rs

@@ -0,0 +1,16 @@
+use async_openai::config::OpenAIConfig;
+use async_openai::Client as OpenAIClient;
+
+pub use super::openai::Client;
+
+impl Client {
+    pub async fn new_openrouter(spec: super::LlmSpec) -> anyhow::Result<Self> {
+        let address = spec.address.clone().unwrap_or_else(|| "https://openrouter.ai/api/v1".to_string());
+        let api_key = std::env::var("OPENROUTER_API_KEY").ok();
+        let mut config = OpenAIConfig::new().with_api_base(address);
+        if let Some(api_key) = api_key {
+            config = config.with_api_key(api_key);
+        }
+        Ok(Client::from_parts(OpenAIClient::with_config(config), spec.model))
+    }
+}