diff --git a/api/cache/getLogStores.js b/api/cache/getLogStores.js
index 7f759e5f33..894edd2162 100644
--- a/api/cache/getLogStores.js
+++ b/api/cache/getLogStores.js
@@ -31,6 +31,10 @@ const genTitle = isEnabled(USE_REDIS) // ttl: 2 minutes
   ? new Keyv({ store: keyvRedis, ttl: 120000 })
   : new Keyv({ namespace: CacheKeys.GEN_TITLE, ttl: 120000 });
 
+const modelQueries = isEnabled(process.env.USE_REDIS)
+  ? new Keyv({ store: keyvRedis })
+  : new Keyv({ namespace: 'models' });
+
 const namespaces = {
   [CacheKeys.CONFIG_STORE]: config,
   pending_req,
@@ -44,6 +48,7 @@ const namespaces = {
   logins: createViolationInstance('logins'),
   [CacheKeys.TOKEN_CONFIG]: tokenConfig,
   [CacheKeys.GEN_TITLE]: genTitle,
+  [CacheKeys.MODEL_QUERIES]: modelQueries,
 };
 
 /**
diff --git a/api/server/controllers/ModelController.js b/api/server/controllers/ModelController.js
index 2d23961e15..0025ef910d 100644
--- a/api/server/controllers/ModelController.js
+++ b/api/server/controllers/ModelController.js
@@ -9,8 +9,8 @@ async function modelController(req, res) {
     res.send(cachedModelsConfig);
     return;
   }
-  const defaultModelsConfig = await loadDefaultModels();
-  const customModelsConfig = await loadConfigModels();
+  const defaultModelsConfig = await loadDefaultModels(req);
+  const customModelsConfig = await loadConfigModels(req);
 
   const modelConfig = { ...defaultModelsConfig, ...customModelsConfig };
 
diff --git a/api/server/services/AuthService.js b/api/server/services/AuthService.js
index 62e3ee8396..0811b10fa2 100644
--- a/api/server/services/AuthService.js
+++ b/api/server/services/AuthService.js
@@ -1,7 +1,7 @@
 const crypto = require('crypto');
 const bcrypt = require('bcryptjs');
 const { registerSchema, errorsToString } = require('~/strategies/validators');
-const getCustomConfig = require('~/cache/getCustomConfig');
+const getCustomConfig = require('~/server/services/Config/getCustomConfig');
 const Token = require('~/models/schema/tokenSchema');
 const { sendEmail } = require('~/server/utils');
 const Session = require('~/models/Session');
diff --git a/api/server/services/AuthService.spec.js b/api/server/services/AuthService.spec.js
index 23aad21d3f..fb5d8e2533 100644
--- a/api/server/services/AuthService.spec.js
+++ b/api/server/services/AuthService.spec.js
@@ -1,7 +1,7 @@
-const getCustomConfig = require('~/cache/getCustomConfig');
+const getCustomConfig = require('~/server/services/Config/getCustomConfig');
 const { isDomainAllowed } = require('./AuthService');
 
-jest.mock('~/cache/getCustomConfig', () => jest.fn());
+jest.mock('~/server/services/Config/getCustomConfig', () => jest.fn());
 
 describe('isDomainAllowed', () => {
   it('should allow domain when customConfig is not available', async () => {
diff --git a/api/cache/getCustomConfig.js b/api/server/services/Config/getCustomConfig.js
similarity index 80%
rename from api/cache/getCustomConfig.js
rename to api/server/services/Config/getCustomConfig.js
index 6d5cf8f275..a479ca37b7 100644
--- a/api/cache/getCustomConfig.js
+++ b/api/server/services/Config/getCustomConfig.js
@@ -1,6 +1,6 @@
 const { CacheKeys } = require('librechat-data-provider');
-const loadCustomConfig = require('~/server/services/Config/loadCustomConfig');
-const getLogStores = require('./getLogStores');
+const loadCustomConfig = require('./loadCustomConfig');
+const getLogStores = require('~/cache/getLogStores');
 
 /**
  * Retrieves the configuration object
diff --git a/api/server/services/Config/index.js b/api/server/services/Config/index.js
index 57a00bf515..2e8ccb1433 100644
--- a/api/server/services/Config/index.js
+++ b/api/server/services/Config/index.js
@@ -1,4 +1,5 @@
 const { config } = require('./EndpointService');
+const getCustomConfig = require('./getCustomConfig');
 const loadCustomConfig = require('./loadCustomConfig');
 const loadConfigModels = require('./loadConfigModels');
 const loadDefaultModels = require('./loadDefaultModels');
@@ -9,6 +10,7 @@ const loadDefaultEndpointsConfig = require('./loadDefaultEConfig');
 
 module.exports = {
   config,
+  getCustomConfig,
   loadCustomConfig,
   loadConfigModels,
   loadDefaultModels,
diff --git a/api/server/services/Config/loadConfigEndpoints.js b/api/server/services/Config/loadConfigEndpoints.js
index 1b435e144e..156688b059 100644
--- a/api/server/services/Config/loadConfigEndpoints.js
+++ b/api/server/services/Config/loadConfigEndpoints.js
@@ -1,18 +1,12 @@
-const { CacheKeys, EModelEndpoint } = require('librechat-data-provider');
+const { EModelEndpoint } = require('librechat-data-provider');
 const { isUserProvided, extractEnvVariable } = require('~/server/utils');
-const loadCustomConfig = require('./loadCustomConfig');
-const { getLogStores } = require('~/cache');
+const getCustomConfig = require('./getCustomConfig');
 
 /**
  * Load config endpoints from the cached configuration object
  * @function loadConfigEndpoints */
 async function loadConfigEndpoints() {
-  const cache = getLogStores(CacheKeys.CONFIG_STORE);
-  let customConfig = await cache.get(CacheKeys.CUSTOM_CONFIG);
-
-  if (!customConfig) {
-    customConfig = await loadCustomConfig();
-  }
+  const customConfig = await getCustomConfig();
 
   if (!customConfig) {
     return {};
diff --git a/api/server/services/Config/loadConfigModels.js b/api/server/services/Config/loadConfigModels.js
index aff8614934..d78ad5950b 100644
--- a/api/server/services/Config/loadConfigModels.js
+++ b/api/server/services/Config/loadConfigModels.js
@@ -1,19 +1,15 @@
-const { CacheKeys, EModelEndpoint } = require('librechat-data-provider');
+const { EModelEndpoint } = require('librechat-data-provider');
 const { isUserProvided, extractEnvVariable } = require('~/server/utils');
 const { fetchModels } = require('~/server/services/ModelService');
-const loadCustomConfig = require('./loadCustomConfig');
-const { getLogStores } = require('~/cache');
+const getCustomConfig = require('./getCustomConfig');
 
 /**
  * Load config endpoints from the cached configuration object
- * @function loadConfigModels */
-async function loadConfigModels() {
-  const cache = getLogStores(CacheKeys.CONFIG_STORE);
-  let customConfig = await cache.get(CacheKeys.CUSTOM_CONFIG);
-
-  if (!customConfig) {
-    customConfig = await loadCustomConfig();
-  }
+ * @function loadConfigModels
+ * @param {Express.Request} req - The Express request object.
+ */
+async function loadConfigModels(req) {
+  const customConfig = await getCustomConfig();
 
   if (!customConfig) {
     return {};
@@ -49,7 +45,14 @@ async function loadConfigModels() {
 
     if (models.fetch && !isUserProvided(API_KEY) && !isUserProvided(BASE_URL)) {
       fetchPromisesMap[BASE_URL] =
-        fetchPromisesMap[BASE_URL] || fetchModels({ baseURL: BASE_URL, apiKey: API_KEY, name });
+        fetchPromisesMap[BASE_URL] ||
+        fetchModels({
+          user: req.user.id,
+          baseURL: BASE_URL,
+          apiKey: API_KEY,
+          name,
+          userIdQuery: models.userIdQuery,
+        });
       baseUrlToNameMap[BASE_URL] = baseUrlToNameMap[BASE_URL] || [];
       baseUrlToNameMap[BASE_URL].push(name);
       continue;
diff --git a/api/server/services/Config/loadCustomConfig.js b/api/server/services/Config/loadCustomConfig.js
index ab99f2aa72..a90083b2fc 100644
--- a/api/server/services/Config/loadCustomConfig.js
+++ b/api/server/services/Config/loadCustomConfig.js
@@ -17,6 +17,7 @@ const configPath = path.resolve(projectRoot, 'librechat.yaml');
 async function loadCustomConfig() {
   const customConfig = loadYaml(configPath);
   if (!customConfig) {
+    logger.info('Custom config file missing or YAML format invalid.');
     return null;
   }
 
@@ -25,7 +26,7 @@ async function loadCustomConfig() {
     logger.error(`Invalid custom config file at ${configPath}`, result.error);
     return null;
   } else {
-    logger.info('Loaded custom config file:');
+    logger.info('Custom config file loaded:');
     logger.info(JSON.stringify(customConfig, null, 2));
   }
 
diff --git a/api/server/services/Config/loadDefaultModels.js b/api/server/services/Config/loadDefaultModels.js
index 665aa71479..e22a9b2769 100644
--- a/api/server/services/Config/loadDefaultModels.js
+++ b/api/server/services/Config/loadDefaultModels.js
@@ -11,13 +11,23 @@ const fitlerAssistantModels = (str) => {
   return /gpt-4|gpt-3\\.5/i.test(str) && !/vision|instruct/i.test(str);
 };
 
-async function loadDefaultModels() {
+/**
+ * Loads the default models for the application.
+ * @async
+ * @function
+ * @param {Express.Request} req - The Express request object.
+ */
+async function loadDefaultModels(req) {
   const google = getGoogleModels();
-  const openAI = await getOpenAIModels();
+  const openAI = await getOpenAIModels({ user: req.user.id });
   const anthropic = getAnthropicModels();
   const chatGPTBrowser = getChatGPTBrowserModels();
-  const azureOpenAI = await getOpenAIModels({ azure: true });
-  const gptPlugins = await getOpenAIModels({ azure: useAzurePlugins, plugins: true });
+  const azureOpenAI = await getOpenAIModels({ user: req.user.id, azure: true });
+  const gptPlugins = await getOpenAIModels({
+    user: req.user.id,
+    azure: useAzurePlugins,
+    plugins: true,
+  });
 
   return {
     [EModelEndpoint.openAI]: openAI,
diff --git a/api/server/services/Endpoints/custom/initializeClient.js b/api/server/services/Endpoints/custom/initializeClient.js
index e5c9a62e83..c308bd6a71 100644
--- a/api/server/services/Endpoints/custom/initializeClient.js
+++ b/api/server/services/Endpoints/custom/initializeClient.js
@@ -1,8 +1,8 @@
 const { EModelEndpoint, CacheKeys } = require('librechat-data-provider');
 const { getUserKey, checkUserKeyExpiry } = require('~/server/services/UserService');
+const getCustomConfig = require('~/server/services/Config/getCustomConfig');
 const { isUserProvided, extractEnvVariable } = require('~/server/utils');
 const { fetchModels } = require('~/server/services/ModelService');
-const getCustomConfig = require('~/cache/getCustomConfig');
 const getLogStores = require('~/cache/getLogStores');
 const { OpenAIClient } = require('~/app');
 
diff --git a/api/server/services/ModelService.js b/api/server/services/ModelService.js
index 9a9f5238f6..45ae11aa1a 100644
--- a/api/server/services/ModelService.js
+++ b/api/server/services/ModelService.js
@@ -1,47 +1,35 @@
-const Keyv = require('keyv');
 const axios = require('axios');
-const HttpsProxyAgent = require('https-proxy-agent');
+const { HttpsProxyAgent } = require('https-proxy-agent');
 const { EModelEndpoint, defaultModels, CacheKeys } = require('librechat-data-provider');
 const { extractBaseURL, inputSchema, processModelData } = require('~/utils');
 const getLogStores = require('~/cache/getLogStores');
-const { isEnabled } = require('~/server/utils');
-const keyvRedis = require('~/cache/keyvRedis');
 const { logger } = require('~/config');
 
 // const { getAzureCredentials, genAzureChatCompletion } = require('~/utils/');
 
 const { openAIApiKey, userProvidedOpenAI } = require('./Config/EndpointService').config;
 
-const modelsCache = isEnabled(process.env.USE_REDIS)
-  ? new Keyv({ store: keyvRedis })
-  : new Keyv({ namespace: 'models' });
-
-const {
-  OPENROUTER_API_KEY,
-  OPENAI_REVERSE_PROXY,
-  CHATGPT_MODELS,
-  ANTHROPIC_MODELS,
-  GOOGLE_MODELS,
-  PROXY,
-} = process.env ?? {};
-
 /**
  * Fetches OpenAI models from the specified base API path or Azure, based on the provided configuration.
  *
  * @param {Object} params - The parameters for fetching the models.
+ * @param {Object} params.user - The user ID to send to the API.
  * @param {string} params.apiKey - The API key for authentication with the API.
  * @param {string} params.baseURL - The base path URL for the API.
  * @param {string} [params.name='OpenAI'] - The name of the API; defaults to 'OpenAI'.
  * @param {boolean} [params.azure=false] - Whether to fetch models from Azure.
+ * @param {boolean} [params.userIdQuery=false] - Whether to send the user ID as a query parameter.
  * @param {boolean} [params.createTokenConfig=true] - Whether to create a token configuration from the API response.
  * @returns {Promise<string[]>} A promise that resolves to an array of model identifiers.
  * @async
  */
 const fetchModels = async ({
+  user,
   apiKey,
   baseURL,
   name = 'OpenAI',
   azure = false,
+  userIdQuery = false,
   createTokenConfig = true,
 }) => {
   let models = [];
@@ -51,21 +39,26 @@ const fetchModels = async ({
   }
 
   try {
-    const payload = {
+    const options = {
       headers: {
         Authorization: `Bearer ${apiKey}`,
       },
     };
 
-    if (PROXY) {
-      payload.httpsAgent = new HttpsProxyAgent(PROXY);
+    if (process.env.PROXY) {
+      options.httpsAgent = new HttpsProxyAgent(process.env.PROXY);
     }
 
     if (process.env.OPENAI_ORGANIZATION && baseURL.includes('openai')) {
-      payload.headers['OpenAI-Organization'] = process.env.OPENAI_ORGANIZATION;
+      options.headers['OpenAI-Organization'] = process.env.OPENAI_ORGANIZATION;
     }
 
-    const res = await axios.get(`${baseURL}${azure ? '' : '/models'}`, payload);
+    const url = new URL(`${baseURL}${azure ? '' : '/models'}`);
+    if (user && userIdQuery) {
+      url.searchParams.append('user', user);
+    }
+    const res = await axios.get(url.toString(), options);
+
     /** @type {z.infer<typeof inputSchema>} */
     const input = res.data;
 
@@ -83,11 +76,22 @@ const fetchModels = async ({
   return models;
 };
 
-const fetchOpenAIModels = async (opts = { azure: false, plugins: false }, _models = []) => {
+/**
+ * Fetches models from the specified API path or Azure, based on the provided options.
+ * @async
+ * @function
+ * @param {object} opts - The options for fetching the models.
+ * @param {string} opts.user - The user ID to send to the API.
+ * @param {boolean} [opts.azure=false] - Whether to fetch models from Azure.
+ * @param {boolean} [opts.plugins=false] - Whether to fetch models from the plugins.
+ * @param {string[]} [_models=[]] - The models to use as a fallback.
+ */
+const fetchOpenAIModels = async (opts, _models = []) => {
   let models = _models.slice() ?? [];
   let apiKey = openAIApiKey;
-  let baseURL = 'https://api.openai.com/v1';
-  let reverseProxyUrl = OPENAI_REVERSE_PROXY;
+  const openaiBaseURL = 'https://api.openai.com/v1';
+  let baseURL = openaiBaseURL;
+  let reverseProxyUrl = process.env.OPENAI_REVERSE_PROXY;
   if (opts.azure) {
     return models;
     // const azure = getAzureCredentials();
@@ -95,15 +99,17 @@ const fetchOpenAIModels = async (opts = { azure: false, plugins: false }, _model
     //   .split('/deployments')[0]
     //   .concat(`/models?api-version=${azure.azureOpenAIApiVersion}`);
     // apiKey = azureOpenAIApiKey;
-  } else if (OPENROUTER_API_KEY) {
+  } else if (process.env.OPENROUTER_API_KEY) {
     reverseProxyUrl = 'https://openrouter.ai/api/v1';
-    apiKey = OPENROUTER_API_KEY;
+    apiKey = process.env.OPENROUTER_API_KEY;
   }
 
   if (reverseProxyUrl) {
     baseURL = extractBaseURL(reverseProxyUrl);
   }
 
+  const modelsCache = getLogStores(CacheKeys.MODEL_QUERIES);
+
   const cachedModels = await modelsCache.get(baseURL);
   if (cachedModels) {
     return cachedModels;
@@ -114,10 +120,15 @@ const fetchOpenAIModels = async (opts = { azure: false, plugins: false }, _model
       apiKey,
       baseURL,
       azure: opts.azure,
+      user: opts.user,
     });
   }
 
-  if (!reverseProxyUrl) {
+  if (models.length === 0) {
+    return _models;
+  }
+
+  if (baseURL === openaiBaseURL) {
     const regex = /(text-davinci-003|gpt-)/;
     models = models.filter((model) => regex.test(model));
   }
@@ -126,18 +137,27 @@ const fetchOpenAIModels = async (opts = { azure: false, plugins: false }, _model
   return models;
 };
 
-const getOpenAIModels = async (opts = { azure: false, plugins: false }) => {
-  let models = [
-    'gpt-4',
-    'gpt-4-0613',
-    'gpt-3.5-turbo',
-    'gpt-3.5-turbo-16k',
-    'gpt-3.5-turbo-0613',
-    'gpt-3.5-turbo-0301',
-  ];
+/**
+ * Loads the default models for the application.
+ * @async
+ * @function
+ * @param {object} opts - The options for fetching the models.
+ * @param {string} opts.user - The user ID to send to the API.
+ * @param {boolean} [opts.azure=false] - Whether to fetch models from Azure.
+ * @param {boolean} [opts.plugins=false] - Whether to fetch models from the plugins.
+ */
+const getOpenAIModels = async (opts) => {
+  let models = defaultModels.openAI;
 
-  if (!opts.plugins) {
-    models.push('text-davinci-003');
+  if (opts.plugins) {
+    models = models.filter(
+      (model) =>
+        !model.includes('text-davinci') &&
+        !model.includes('instruct') &&
+        !model.includes('0613') &&
+        !model.includes('0314') &&
+        !model.includes('0301'),
+    );
   }
 
   let key;
@@ -154,7 +174,7 @@ const getOpenAIModels = async (opts = { azure: false, plugins: false }) => {
     return models;
   }
 
-  if (userProvidedOpenAI && !OPENROUTER_API_KEY) {
+  if (userProvidedOpenAI && !process.env.OPENROUTER_API_KEY) {
     return models;
   }
 
@@ -163,8 +183,8 @@ const getOpenAIModels = async (opts = { azure: false, plugins: false }) => {
 
 const getChatGPTBrowserModels = () => {
   let models = ['text-davinci-002-render-sha', 'gpt-4'];
-  if (CHATGPT_MODELS) {
-    models = String(CHATGPT_MODELS).split(',');
+  if (process.env.CHATGPT_MODELS) {
+    models = String(process.env.CHATGPT_MODELS).split(',');
   }
 
   return models;
@@ -172,8 +192,8 @@ const getChatGPTBrowserModels = () => {
 
 const getAnthropicModels = () => {
   let models = defaultModels[EModelEndpoint.anthropic];
-  if (ANTHROPIC_MODELS) {
-    models = String(ANTHROPIC_MODELS).split(',');
+  if (process.env.ANTHROPIC_MODELS) {
+    models = String(process.env.ANTHROPIC_MODELS).split(',');
   }
 
   return models;
@@ -181,8 +201,8 @@ const getAnthropicModels = () => {
 
 const getGoogleModels = () => {
   let models = defaultModels[EModelEndpoint.google];
-  if (GOOGLE_MODELS) {
-    models = String(GOOGLE_MODELS).split(',');
+  if (process.env.GOOGLE_MODELS) {
+    models = String(process.env.GOOGLE_MODELS).split(',');
   }
 
   return models;
diff --git a/api/server/services/ModelService.spec.js b/api/server/services/ModelService.spec.js
new file mode 100644
index 0000000000..19fa407ce8
--- /dev/null
+++ b/api/server/services/ModelService.spec.js
@@ -0,0 +1,212 @@
+const axios = require('axios');
+
+const { fetchModels, getOpenAIModels } = require('./ModelService');
+jest.mock('~/utils', () => {
+  const originalUtils = jest.requireActual('~/utils');
+  return {
+    ...originalUtils,
+    processModelData: jest.fn((...args) => {
+      return originalUtils.processModelData(...args);
+    }),
+  };
+});
+
+jest.mock('axios');
+jest.mock('~/cache/getLogStores', () =>
+  jest.fn().mockImplementation(() => ({
+    get: jest.fn().mockResolvedValue(undefined),
+    set: jest.fn().mockResolvedValue(true),
+  })),
+);
+jest.mock('~/config', () => ({
+  logger: {
+    error: jest.fn(),
+  },
+}));
+jest.mock('./Config/EndpointService', () => ({
+  config: {
+    openAIApiKey: 'mockedApiKey',
+    userProvidedOpenAI: false,
+  },
+}));
+
+axios.get.mockResolvedValue({
+  data: {
+    data: [{ id: 'model-1' }, { id: 'model-2' }],
+  },
+});
+
+describe('fetchModels', () => {
+  it('fetches models successfully from the API', async () => {
+    const models = await fetchModels({
+      user: 'user123',
+      apiKey: 'testApiKey',
+      baseURL: 'https://api.test.com',
+      name: 'TestAPI',
+    });
+
+    expect(models).toEqual(['model-1', 'model-2']);
+    expect(axios.get).toHaveBeenCalledWith(
+      expect.stringContaining('https://api.test.com/models'),
+      expect.any(Object),
+    );
+  });
+
+  it('adds the user ID to the models query when option and ID are passed', async () => {
+    const models = await fetchModels({
+      user: 'user123',
+      apiKey: 'testApiKey',
+      baseURL: 'https://api.test.com',
+      userIdQuery: true,
+      name: 'TestAPI',
+    });
+
+    expect(models).toEqual(['model-1', 'model-2']);
+    expect(axios.get).toHaveBeenCalledWith(
+      expect.stringContaining('https://api.test.com/models?user=user123'),
+      expect.any(Object),
+    );
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+});
+
+describe('fetchModels with createTokenConfig true', () => {
+  const data = {
+    data: [
+      {
+        id: 'model-1',
+        pricing: {
+          prompt: '0.002',
+          completion: '0.001',
+        },
+        context_length: 1024,
+      },
+      {
+        id: 'model-2',
+        pricing: {
+          prompt: '0.003',
+          completion: '0.0015',
+        },
+        context_length: 2048,
+      },
+    ],
+  };
+
+  beforeEach(() => {
+    // Clears the mock's history before each test
+    const _utils = require('~/utils');
+    axios.get.mockResolvedValue({ data });
+  });
+
+  it('creates and stores token configuration if createTokenConfig is true', async () => {
+    await fetchModels({
+      user: 'user123',
+      apiKey: 'testApiKey',
+      baseURL: 'https://api.test.com',
+      createTokenConfig: true,
+    });
+
+    const { processModelData } = require('~/utils');
+    expect(processModelData).toHaveBeenCalled();
+    expect(processModelData).toHaveBeenCalledWith(data);
+  });
+});
+
+describe('getOpenAIModels', () => {
+  let originalEnv;
+
+  beforeEach(() => {
+    originalEnv = { ...process.env };
+    axios.get.mockRejectedValue(new Error('Network error'));
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+    axios.get.mockReset();
+  });
+
+  it('returns default models when no environment configurations are provided (and fetch fails)', async () => {
+    const models = await getOpenAIModels({ user: 'user456' });
+    expect(models).toContain('gpt-4');
+  });
+
+  it('returns `AZURE_OPENAI_MODELS` with `azure` flag (and fetch fails)', async () => {
+    process.env.AZURE_OPENAI_MODELS = 'azure-model,azure-model-2';
+    const models = await getOpenAIModels({ azure: true });
+    expect(models).toEqual(expect.arrayContaining(['azure-model', 'azure-model-2']));
+  });
+
+  it('returns `PLUGIN_MODELS` with `plugins` flag (and fetch fails)', async () => {
+    process.env.PLUGIN_MODELS = 'plugins-model,plugins-model-2';
+    const models = await getOpenAIModels({ plugins: true });
+    expect(models).toEqual(expect.arrayContaining(['plugins-model', 'plugins-model-2']));
+  });
+
+  it('returns `OPENAI_MODELS` with no flags (and fetch fails)', async () => {
+    process.env.OPENAI_MODELS = 'openai-model,openai-model-2';
+    const models = await getOpenAIModels({});
+    expect(models).toEqual(expect.arrayContaining(['openai-model', 'openai-model-2']));
+  });
+
+  it('attempts to use OPENROUTER_API_KEY if set', async () => {
+    process.env.OPENROUTER_API_KEY = 'test-router-key';
+    const expectedModels = ['model-router-1', 'model-router-2'];
+
+    axios.get.mockResolvedValue({
+      data: {
+        data: expectedModels.map((id) => ({ id })),
+      },
+    });
+
+    const models = await getOpenAIModels({ user: 'user456' });
+
+    expect(models).toEqual(expect.arrayContaining(expectedModels));
+    expect(axios.get).toHaveBeenCalled();
+  });
+
+  it('utilizes proxy configuration when PROXY is set', async () => {
+    axios.get.mockResolvedValue({
+      data: {
+        data: [],
+      },
+    });
+    process.env.PROXY = 'http://localhost:8888';
+    await getOpenAIModels({ user: 'user456' });
+
+    expect(axios.get).toHaveBeenCalledWith(
+      expect.any(String),
+      expect.objectContaining({
+        httpsAgent: expect.anything(),
+      }),
+    );
+  });
+});
+
+describe('getOpenAIModels with mocked config', () => {
+  it('uses alternative behavior when userProvidedOpenAI is true', async () => {
+    jest.mock('./Config/EndpointService', () => ({
+      config: {
+        openAIApiKey: 'mockedApiKey',
+        userProvidedOpenAI: true,
+      },
+    }));
+    jest.mock('librechat-data-provider', () => {
+      const original = jest.requireActual('librechat-data-provider');
+      return {
+        ...original,
+        defaultModels: {
+          [original.EModelEndpoint.openAI]: ['some-default-model'],
+        },
+      };
+    });
+
+    jest.resetModules();
+    const { getOpenAIModels } = require('./ModelService');
+
+    const models = await getOpenAIModels({ user: 'user456' });
+    expect(models).toContain('some-default-model');
+  });
+});
diff --git a/bun.lockb b/bun.lockb
index 9fd1d656d1..c97b397047 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/docs/install/configuration/custom_config.md b/docs/install/configuration/custom_config.md
index a45cd69a44..fde2cccc81 100644
--- a/docs/install/configuration/custom_config.md
+++ b/docs/install/configuration/custom_config.md
@@ -242,6 +242,9 @@ endpoints:
     - Type: Boolean
     - Example: `fetch: true`
     - **Note**: May cause slowdowns during initial use of the app if the response is delayed. Defaults to `false`.
+  - **userIdQuery**: When set to `true`, adds the LibreChat user ID as a query parameter to the API models request.
+    - Type: Boolean
+    - Example: `userIdQuery: true`
 
 ### **titleConvo**:
 
diff --git a/package.json b/package.json
index 526a6d289a..48209877b4 100644
--- a/package.json
+++ b/package.json
@@ -50,8 +50,8 @@
     "format": "prettier-eslint --write \"{,!(node_modules)/**/}*.{js,jsx,ts,tsx}\"",
     "b:api": "NODE_ENV=production bun run api/server/index.js",
     "b:api:dev": "NODE_ENV=production bun run --watch api/server/index.js",
-    "b:data-provider": "cd packages/data-provider && bun run b:build",
-    "b:client": "bun --bun run b:data-provider && cd client && bun --bun run b:build",
+    "b:data": "cd packages/data-provider && bun run b:build",
+    "b:client": "bun --bun run b:data && cd client && bun --bun run b:build",
     "b:client:dev": "cd client && bun run b:dev",
     "b:test:client": "cd client && bun run b:test",
     "b:test:api": "cd api && bun run b:test",
diff --git a/packages/data-provider/src/config.ts b/packages/data-provider/src/config.ts
index 44c0a260b4..753b35bb85 100644
--- a/packages/data-provider/src/config.ts
+++ b/packages/data-provider/src/config.ts
@@ -15,6 +15,7 @@ export const endpointSchema = z.object({
   models: z.object({
     default: z.array(z.string()).min(1),
     fetch: z.boolean().optional(),
+    userIdQuery: z.boolean().optional(),
   }),
   titleConvo: z.boolean().optional(),
   titleMethod: z.union([z.literal('completion'), z.literal('functions')]).optional(),
@@ -40,7 +41,8 @@ export const configSchema = z.object({
     .object({
       custom: z.array(endpointSchema.partial()),
     })
-    .strict(),
+    .strict()
+    .optional(),
 });
 
 export type TCustomConfig = z.infer<typeof configSchema>;
@@ -177,6 +179,10 @@ export enum CacheKeys {
    * Key for the model config cache.
    */
   MODELS_CONFIG = 'modelsConfig',
+  /**
+   * Key for the model queries cache.
+   */
+  MODEL_QUERIES = 'modelQueries',
   /**
    * Key for the default endpoint config cache.
    */