diff --git a/web/src/interfaces/database/llm.ts b/web/src/interfaces/database/llm.ts
index 2a71acd238..2b7c86eef6 100644
--- a/web/src/interfaces/database/llm.ts
+++ b/web/src/interfaces/database/llm.ts
@@ -62,7 +62,7 @@ export interface IProviderInstance {
   status: string;
   /**
    * Optional: only returned by the showProviderInstance endpoint. Used
-   * to pre-fill the base_url/api_base form field when opening a saved
+   * to pre-fill the base_url form field when opening a saved
    * instance.
    */
   base_url?: string;
diff --git a/web/src/pages/user-setting/setting-model/instance-card/hooks.tsx b/web/src/pages/user-setting/setting-model/instance-card/hooks.tsx
index dc84f2f250..341452474e 100644
--- a/web/src/pages/user-setting/setting-model/instance-card/hooks.tsx
+++ b/web/src/pages/user-setting/setting-model/instance-card/hooks.tsx
@@ -105,7 +105,7 @@ function pickDefaultUrl(
 
 /**
  * Fetch the catalog of available providers and derive the
- * `base_url` / `api_base` dropdown options for the current provider.
+ * `base_url` dropdown options for the current provider.
  * Used to pre-fill the URL field with the provider's default URL when
  * creating a new instance.
  */
@@ -157,7 +157,7 @@ export function useProviderBaseUrlOptions(providerName: string) {
  * lazy-loaded `showProviderInstance` details, and the provider's default
  * base URL.
  *
- * - Draft: empty form, with `base_url` / `api_base` pre-filled from the
+ * - Draft: empty form, with `base_url` pre-filled from the
  *   provider's `default` URL when available.
  * - Saved: prefer `instanceDetails` (which carries api_key / base_url);
  *   normalise api_key into the bare key plus any nested credential
@@ -176,7 +176,6 @@ export function useProviderInitialValues(
       const values: Record<string, any> = { instance_name: '' };
       if (defaultBaseUrl) {
         values.base_url = defaultBaseUrl;
-        values.api_base = defaultBaseUrl;
       }
       return values;
     }
@@ -200,10 +199,8 @@ export function useProviderInitialValues(
     }
     if (merged.base_url) {
       values.base_url = merged.base_url;
-      values.api_base = merged.base_url;
     } else if (defaultBaseUrl) {
       values.base_url = defaultBaseUrl;
-      values.api_base = defaultBaseUrl;
     }
     // The /providers/<p>/instances/<i> endpoint also returns `region`
     // for providers where it applies; surface it so the form / region
@@ -290,7 +287,7 @@ export function useFormResetOnDetailsLoad(
  *  maps provider-specific form field names (e.g. OpenDataLoader's
  *  `opendataloader_apiserver`) onto the `{ apiKey, baseUrl, modelInfo }`
  *  shape the verify endpoint expects. When absent the generic mapping
- *  (`values.api_key` / `values.base_url ?? values.api_base`) is used. */
+ *  (`values.api_key` / `values.base_url`) is used. */
 type VerifyTransform = (values: Record<string, any>) => {
   apiKey: string | object | Record<string, any>;
   baseUrl?: string;
@@ -336,7 +333,7 @@ export function useVerifyProvider(
       } else {
         verifyArgs = {
           api_key: values.api_key ?? '',
-          base_url: values.base_url ?? values.api_base,
+          base_url: values.base_url,
           model_info: values.model_info,
         };
       }
@@ -481,7 +478,7 @@ export function useInstanceSaveState({
     // Provider-specific field mapping (e.g. OpenDataLoader's nested
     // `opendataloader_apiserver` / `opendataloader_api_key`). The
     // transform produces the canonical submit body shape
-    // (`instance_name`, `llm_factory`, `api_key`, `api_base`,
+    // (`instance_name`, `llm_factory`, `api_key`, `base_url`,
     // `model_info`); we then layer on the card's own state (typed /
     // edited name, model_info ref, update-only fields for saved cards).
     if (submitTransform) {
@@ -505,7 +502,7 @@ export function useInstanceSaveState({
         provider_name: providerName,
         instance_name: editedNameRef.current,
         id: resolvedId,
-        base_url: transformed.base_url ?? transformed.api_base ?? '',
+        base_url: transformed.base_url ?? '',
         region: values.region || 'default',
         model_info: modelInfo,
         verify: false,
@@ -519,7 +516,7 @@ export function useInstanceSaveState({
         llm_factory: providerName,
         instance_name: trimmed,
         api_key: buildApiKeyValue(values) ?? '',
-        base_url: values.base_url ?? values.api_base,
+        base_url: values.base_url,
       };
       if (modelInfoRef.current.length > 0) {
         payload.model_info = modelInfoRef.current;
@@ -536,7 +533,7 @@ export function useInstanceSaveState({
       instance_name: editedNameRef.current,
       id: resolvedId,
       api_key: apiKeyValue ?? '',
-      base_url: values.base_url ?? values.api_base,
+      base_url: values.base_url,
       region: values.region || 'default',
       model_info: modelInfoRef.current.length > 0 ? modelInfoRef.current : [],
       verify: false,
@@ -570,7 +567,7 @@ export function useInstanceSaveState({
       instance_name: instanceName,
       id: resolvedId,
       api_key: buildApiKeyValue(initialValues),
-      base_url: initialValues.base_url ?? initialValues.api_base,
+      base_url: initialValues.base_url,
       region: initialValues.region,
       // model_info baseline is `[]`; `markModelsEdited` rewrites it after
       // a model PATCH so the next top-save short-circuits. The first
diff --git a/web/src/pages/user-setting/setting-model/instance-card/models-section/hooks.ts b/web/src/pages/user-setting/setting-model/instance-card/models-section/hooks.ts
index 74c1cb162b..d3fca46f8b 100644
--- a/web/src/pages/user-setting/setting-model/instance-card/models-section/hooks.ts
+++ b/web/src/pages/user-setting/setting-model/instance-card/models-section/hooks.ts
@@ -101,11 +101,7 @@ export function useResolveCreds(
     const fv = getFormValues?.() ?? {};
     return {
       apiKey: (fv.api_key as string) ?? instance?.api_key ?? '',
-      baseUrl:
-        (fv.base_url as string) ??
-        (fv.api_base as string) ??
-        instance?.base_url ??
-        '',
+      baseUrl: (fv.base_url as string) ?? instance?.base_url ?? '',
     };
   }, [getFormValues, instance]);
 
diff --git a/web/src/pages/user-setting/setting-model/instance-card/models-section/interface.ts b/web/src/pages/user-setting/setting-model/instance-card/models-section/interface.ts
index 047c70a933..f97ce0c2ea 100644
--- a/web/src/pages/user-setting/setting-model/instance-card/models-section/interface.ts
+++ b/web/src/pages/user-setting/setting-model/instance-card/models-section/interface.ts
@@ -47,7 +47,7 @@ export interface ModelsSectionProps {
   hideIfEmpty?: boolean;
   /**
    * Optional getter returning the host card's current form values
-   * (`api_key`, `base_url` / `api_base`, region-specific fields, ...).
+   * (`api_key`, `base_url`, region-specific fields, ...).
    * When provided, ModelsSection prefers these over the persisted
    * `instance` props when calling listProviderModels / verifyProviderConnection,
    * so the user can verify with values they are still editing (before
diff --git a/web/src/pages/user-setting/setting-model/payload-utils.ts b/web/src/pages/user-setting/setting-model/payload-utils.ts
index 9f997a49c5..a6f2562ea8 100644
--- a/web/src/pages/user-setting/setting-model/payload-utils.ts
+++ b/web/src/pages/user-setting/setting-model/payload-utils.ts
@@ -30,7 +30,6 @@ const INSTANCE_RESERVED_KEYS = new Set([
   'instance_name',
   'llm_factory',
   'provider_name',
-  'api_base',
   'base_url',
   'region',
   'verify',
@@ -113,20 +112,13 @@ const collectModelExtras = (payload: FlatPayload) => {
 };
 
 export const splitProviderPayload = (payload: FlatPayload): SplitResult => {
-  const {
-    instance_name,
-    llm_factory,
-    base_url,
-    api_base,
-    region,
-    model_info,
-    ...other
-  } = payload;
+  const { instance_name, llm_factory, base_url, region, model_info, ...other } =
+    payload;
   const instancePayload = {
     instance_name: instance_name as string,
     llm_factory: llm_factory as string,
     api_key: collectApiKeyExtras(payload),
-    base_url: (base_url ?? api_base) as string | undefined,
+    base_url: base_url as string | undefined,
     region: (region as string | undefined) || 'default',
     model_info: model_info,
     ...other,
diff --git a/web/src/pages/user-setting/setting-model/provider-schema/field-config/generic-api-key-config.ts b/web/src/pages/user-setting/setting-model/provider-schema/field-config/generic-api-key-config.ts
index 31ee99c108..b524422a6c 100644
--- a/web/src/pages/user-setting/setting-model/provider-schema/field-config/generic-api-key-config.ts
+++ b/web/src/pages/user-setting/setting-model/provider-schema/field-config/generic-api-key-config.ts
@@ -84,7 +84,7 @@ export const GenericApiKeyConfig: ProviderConfig = {
     return {
       instance_name: values.instance_name,
       api_key: apiKey,
-      api_base: values.base_url || '',
+      base_url: values.base_url || '',
     };
   },
 };
diff --git a/web/src/pages/user-setting/setting-model/provider-schema/field-config/local-llm-configs.ts b/web/src/pages/user-setting/setting-model/provider-schema/field-config/local-llm-configs.ts
index f2c6a1a444..218e45aafb 100644
--- a/web/src/pages/user-setting/setting-model/provider-schema/field-config/local-llm-configs.ts
+++ b/web/src/pages/user-setting/setting-model/provider-schema/field-config/local-llm-configs.ts
@@ -306,7 +306,7 @@ function buildLocalConfig(
         instance_name: values.instance_name,
         llm_factory: llmFactory,
         model_info: buildModelInfoFromValues(values),
-        api_base: values.base_url,
+        base_url: values.base_url,
         api_key: apiKey,
       };
     },
diff --git a/web/src/pages/user-setting/setting-model/provider-schema/field-config/provider-config-map.ts b/web/src/pages/user-setting/setting-model/provider-schema/field-config/provider-config-map.ts
index 4f744cbe81..b3b956bf59 100644
--- a/web/src/pages/user-setting/setting-model/provider-schema/field-config/provider-config-map.ts
+++ b/web/src/pages/user-setting/setting-model/provider-schema/field-config/provider-config-map.ts
@@ -39,7 +39,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
         validation: { message: 'instanceNameMessage' },
       },
       {
-        name: 'api_base',
+        name: 'base_url',
         label: 'addLlmBaseUrl',
         type: 'inputSelect',
         required: true,
@@ -67,7 +67,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
     ],
     verifyTransform: (values) => ({
       apiKey: values.api_key,
-      baseUrl: values.api_base,
+      baseUrl: values.base_url,
       modelInfo: [],
     }),
     submitTransform: (values) => {
@@ -77,7 +77,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
       return {
         instance_name: values.instance_name,
         llm_factory: LLMFactory.AzureOpenAI,
-        api_base: values.api_base,
+        base_url: values.base_url,
         api_key: apiKey,
         model_info: [],
       };
@@ -464,7 +464,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
         instance_name: values.instance_name,
         llm_factory: LLMFactory.OpenDataLoader,
         api_key: cfg,
-        api_base: '',
+        base_url: '',
         model_info: [],
       };
     },
@@ -543,7 +543,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
         instance_name: values.instance_name,
         llm_factory: LLMFactory.PaddleOCR,
         api_key: cfg,
-        api_base: '',
+        base_url: '',
         model_info: [],
       };
     },
@@ -638,7 +638,7 @@ export const ProviderConfigMap: Record<string, ProviderConfig> = {
         instance_name: values.instance_name,
         llm_factory: LLMFactory.MinerU,
         api_key: cfg,
-        api_base: '',
+        base_url: '',
         model_info: [],
       };
     },
diff --git a/web/src/pages/user-setting/setting-model/provider-schema/types.ts b/web/src/pages/user-setting/setting-model/provider-schema/types.ts
index e19cbf3a5e..5aeb49db03 100644
--- a/web/src/pages/user-setting/setting-model/provider-schema/types.ts
+++ b/web/src/pages/user-setting/setting-model/provider-schema/types.ts
@@ -189,7 +189,7 @@ export interface ProviderModalProps {
   initialValues?: Record<string, any>;
   /**
    * Base URL options for the input+select combo (from IAvailableProvider.url)
-   * Used by base_url/api_base fields of type inputSelect
+   * Used by base_url fields of type inputSelect
    */
   baseUrlOptions?: SelectOption[];
   onOk: (payload: any, isVerify?: boolean) => Promise<any>;