diff --git a/README.md b/README.md
index 74c0988..7efc83f 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ Diagrams are represented as XML that can be rendered in draw.io. The AI processe
 ## Multi-Provider Support
 
 -   AWS Bedrock (default)
--   OpenAI
+-   OpenAI / OpenAI-compatible APIs (via `OPENAI_BASE_URL`)
 -   Anthropic
 -   Google AI
 -   Azure OpenAI
diff --git a/env.example b/env.example
index f6fb271..8d01d0e 100644
--- a/env.example
+++ b/env.example
@@ -14,6 +14,7 @@ AI_MODEL=global.anthropic.claude-sonnet-4-5-20250929-v1:0
 
 # OpenAI Configuration
 # OPENAI_API_KEY=sk-...
+# OPENAI_BASE_URL=https://api.openai.com/v1  # Optional: Custom OpenAI-compatible endpoint
 # OPENAI_ORGANIZATION=org-...  # Optional
 # OPENAI_PROJECT=proj_...      # Optional
 
diff --git a/lib/ai-providers.ts b/lib/ai-providers.ts
index d3e9692..13c359e 100644
--- a/lib/ai-providers.ts
+++ b/lib/ai-providers.ts
@@ -1,5 +1,5 @@
 import { bedrock } from '@ai-sdk/amazon-bedrock';
-import { openai } from '@ai-sdk/openai';
+import { openai, createOpenAI } from '@ai-sdk/openai';
 import { anthropic } from '@ai-sdk/anthropic';
 import { google } from '@ai-sdk/google';
 import { azure } from '@ai-sdk/azure';
@@ -61,6 +61,7 @@ function validateProviderCredentials(provider: ProviderName): void {
  *
  * Provider-specific env vars:
  * - OPENAI_API_KEY: OpenAI API key
+ * - OPENAI_BASE_URL: Custom OpenAI-compatible endpoint (optional)
  * - ANTHROPIC_API_KEY: Anthropic API key
  * - GOOGLE_GENERATIVE_AI_API_KEY: Google API key
  * - AZURE_RESOURCE_NAME, AZURE_API_KEY: Azure OpenAI credentials
@@ -97,7 +98,15 @@ export function getAIModel(): ModelConfig {
       break;
 
     case 'openai':
-      model = openai(modelId);
+      if (process.env.OPENAI_BASE_URL) {
+        const customOpenAI = createOpenAI({
+          apiKey: process.env.OPENAI_API_KEY,
+          baseURL: process.env.OPENAI_BASE_URL,
+        });
+        model = customOpenAI.chat(modelId);
+      } else {
+        model = openai(modelId);
+      }
       break;
 
     case 'anthropic':