diff --git a/README.md b/README.md
index c5d4a86a..3c4baed1 100644
--- a/README.md
+++ b/README.md
@@ -50,7 +50,7 @@ import com.openai.models.ChatModel;
 import com.openai.models.chat.completions.ChatCompletion;
 import com.openai.models.chat.completions.ChatCompletionCreateParams;
 
-// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID` and `OPENAI_PROJECT_ID` environment variables
+// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID`, `OPENAI_PROJECT_ID` and `OPENAI_BASE_URL` environment variables
 OpenAIClient client = OpenAIOkHttpClient.fromEnv();
 
 ChatCompletionCreateParams params = ChatCompletionCreateParams.builder()
@@ -68,7 +68,7 @@ Configure the client using environment variables:
 import com.openai.client.OpenAIClient;
 import com.openai.client.okhttp.OpenAIOkHttpClient;
 
-// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID` and `OPENAI_PROJECT_ID` environment variables
+// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID`, `OPENAI_PROJECT_ID` and `OPENAI_BASE_URL` environment variables
 OpenAIClient client = OpenAIOkHttpClient.fromEnv();
 ```
 
@@ -90,7 +90,7 @@ import com.openai.client.OpenAIClient;
 import com.openai.client.okhttp.OpenAIOkHttpClient;
 
 OpenAIClient client = OpenAIOkHttpClient.builder()
-    // Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID` and `OPENAI_PROJECT_ID` environment variables
+    // Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID`, `OPENAI_PROJECT_ID` and `OPENAI_BASE_URL` environment variables
     .fromEnv()
     .apiKey("My API Key")
     .build();
@@ -98,11 +98,12 @@ OpenAIClient client = OpenAIOkHttpClient.builder()
 
 See this table for the available options:
 
-| Setter         | Environment variable | Required | Default value |
-| -------------- | -------------------- | -------- | ------------- |
-| `apiKey`       | `OPENAI_API_KEY`     | true     | -             |
-| `organization` | `OPENAI_ORG_ID`      | false    | -             |
-| `project`      | `OPENAI_PROJECT_ID`  | false    | -             |
+| Setter         | Environment variable | Required | Default value                 |
+| -------------- | -------------------- | -------- | ----------------------------- |
+| `apiKey`       | `OPENAI_API_KEY`     | true     | -                             |
+| `organization` | `OPENAI_ORG_ID`      | false    | -                             |
+| `project`      | `OPENAI_PROJECT_ID`  | false    | -                             |
+| `baseUrl`      | `OPENAI_BASE_URL`    | true     | `"https://api.openai.com/v1"` |
 
 > [!TIP]
 > Don't create more than one client in the same application. Each client has a connection pool and
@@ -134,7 +135,7 @@ import com.openai.models.chat.completions.ChatCompletion;
 import com.openai.models.chat.completions.ChatCompletionCreateParams;
 import java.util.concurrent.CompletableFuture;
 
-// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID` and `OPENAI_PROJECT_ID` environment variables
+// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID`, `OPENAI_PROJECT_ID` and `OPENAI_BASE_URL` environment variables
 OpenAIClient client = OpenAIOkHttpClient.fromEnv();
 
 ChatCompletionCreateParams params = ChatCompletionCreateParams.builder()
@@ -154,7 +155,7 @@ import com.openai.models.chat.completions.ChatCompletion;
 import com.openai.models.chat.completions.ChatCompletionCreateParams;
 import java.util.concurrent.CompletableFuture;
 
-// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID` and `OPENAI_PROJECT_ID` environment variables
+// Configures using the `OPENAI_API_KEY`, `OPENAI_ORG_ID`, `OPENAI_PROJECT_ID` and `OPENAI_BASE_URL` environment variables
 OpenAIClientAsync client = OpenAIOkHttpClientAsync.fromEnv();
 
 ChatCompletionCreateParams params = ChatCompletionCreateParams.builder()
diff --git a/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClient.kt b/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClient.kt
index ccf5dcd7..797a50c3 100644
--- a/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClient.kt
+++ b/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClient.kt
@@ -30,14 +30,10 @@ class OpenAIOkHttpClient private constructor() {
     class Builder internal constructor() {
 
         private var clientOptions: ClientOptions.Builder = ClientOptions.builder()
-        private var baseUrl: String = ClientOptions.PRODUCTION_URL
         private var timeout: Timeout = Timeout.default()
         private var proxy: Proxy? = null
 
-        fun baseUrl(baseUrl: String) = apply {
-            clientOptions.baseUrl(baseUrl)
-            this.baseUrl = baseUrl
-        }
+        fun baseUrl(baseUrl: String) = apply { clientOptions.baseUrl(baseUrl) }
 
         /**
          * Whether to throw an exception if any of the Jackson versions detected at runtime are
@@ -184,7 +180,7 @@ class OpenAIOkHttpClient private constructor() {
                 clientOptions
                     .httpClient(
                         OkHttpClient.builder()
-                            .baseUrl(baseUrl)
+                            .baseUrl(clientOptions.baseUrl())
                             .timeout(timeout)
                             .proxy(proxy)
                             .build()
diff --git a/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClientAsync.kt b/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClientAsync.kt
index 1c183738..b4569aa0 100644
--- a/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClientAsync.kt
+++ b/openai-java-client-okhttp/src/main/kotlin/com/openai/client/okhttp/OpenAIOkHttpClientAsync.kt
@@ -30,14 +30,10 @@ class OpenAIOkHttpClientAsync private constructor() {
     class Builder internal constructor() {
 
         private var clientOptions: ClientOptions.Builder = ClientOptions.builder()
-        private var baseUrl: String = ClientOptions.PRODUCTION_URL
         private var timeout: Timeout = Timeout.default()
         private var proxy: Proxy? = null
 
-        fun baseUrl(baseUrl: String) = apply {
-            clientOptions.baseUrl(baseUrl)
-            this.baseUrl = baseUrl
-        }
+        fun baseUrl(baseUrl: String) = apply { clientOptions.baseUrl(baseUrl) }
 
         /**
          * Whether to throw an exception if any of the Jackson versions detected at runtime are
@@ -184,7 +180,7 @@ class OpenAIOkHttpClientAsync private constructor() {
                 clientOptions
                     .httpClient(
                         OkHttpClient.builder()
-                            .baseUrl(baseUrl)
+                            .baseUrl(clientOptions.baseUrl())
                             .timeout(timeout)
                             .proxy(proxy)
                             .build()
diff --git a/openai-java-core/src/main/kotlin/com/openai/core/ClientOptions.kt b/openai-java-core/src/main/kotlin/com/openai/core/ClientOptions.kt
index d2b4aeaa..a4501bee 100644
--- a/openai-java-core/src/main/kotlin/com/openai/core/ClientOptions.kt
+++ b/openai-java-core/src/main/kotlin/com/openai/core/ClientOptions.kt
@@ -217,7 +217,10 @@ private constructor(
 
         fun removeAllQueryParams(keys: Set<String>) = apply { queryParams.removeAll(keys) }
 
+        fun baseUrl(): String = baseUrl
+
         fun fromEnv() = apply {
+            System.getenv("OPENAI_BASE_URL")?.let { baseUrl(it) }
             System.getenv("OPENAI_API_KEY")?.let { apiKey(it) }
             System.getenv("OPENAI_ORG_ID")?.let { organization(it) }
             System.getenv("OPENAI_PROJECT_ID")?.let { project(it) }