diff --git a/.env.example b/.env.example
index 3bc352c24b..2f49cc517a 100644
--- a/.env.example
+++ b/.env.example
@@ -117,6 +117,12 @@ DEBUG_OPENAI=false # Set to true to enable debug mode for the OpenAI endpoint
 # https://github.com/waylaidwanderer/node-chatgpt-api#using-a-reverse-proxy 
 # OPENAI_REVERSE_PROXY=
 
+# (Advanced) Sometimes when using Local LLM APIs, you may need to force the API
+# to be called with a `prompt` payload instead of a `messages` payload; to mimic the
+# a `/v1/completions` request instead of `/v1/chat/completions`
+# This may be the case for LocalAI with some models. To do so, uncomment the following:
+# OPENAI_FORCE_PROMPT=true
+
 ##########################
 # OpenRouter (overrides OpenAI and Plugins Endpoints): 
 ##########################
diff --git a/api/app/clients/OpenAIClient.js b/api/app/clients/OpenAIClient.js
index b49ef70f7d..b8673d9d88 100644
--- a/api/app/clients/OpenAIClient.js
+++ b/api/app/clients/OpenAIClient.js
@@ -4,6 +4,7 @@ const BaseClient = require('./BaseClient');
 const { getModelMaxTokens, genAzureChatCompletion } = require('../../utils');
 const { truncateText, formatMessage, CUT_OFF_PROMPT } = require('./prompts');
 const spendTokens = require('../../models/spendTokens');
+const { isEnabled } = require('../../server/utils');
 const { createLLM, RunManager } = require('./llm');
 const { summaryBuffer } = require('./memory');
 const { runTitleChain } = require('./chains');
@@ -71,20 +72,22 @@ class OpenAIClient extends BaseClient {
       };
     }
 
-    if (process.env.OPENROUTER_API_KEY) {
-      this.apiKey = process.env.OPENROUTER_API_KEY;
+    const { OPENROUTER_API_KEY, OPENAI_FORCE_PROMPT } = process.env ?? {};
+    if (OPENROUTER_API_KEY) {
+      this.apiKey = OPENROUTER_API_KEY;
       this.useOpenRouter = true;
     }
 
+    const { reverseProxyUrl: reverseProxy } = this.options;
+    this.FORCE_PROMPT =
+      isEnabled(OPENAI_FORCE_PROMPT) ||
+      (reverseProxy && reverseProxy.includes('completions') && !reverseProxy.includes('chat'));
+
     const { model } = this.modelOptions;
 
-    this.isChatCompletion =
-      this.useOpenRouter ||
-      this.options.reverseProxyUrl ||
-      this.options.localAI ||
-      model.includes('gpt-');
+    this.isChatCompletion = this.useOpenRouter || !!reverseProxy || model.includes('gpt-');
     this.isChatGptModel = this.isChatCompletion;
-    if (model.includes('text-davinci-003') || model.includes('instruct')) {
+    if (model.includes('text-davinci-003') || model.includes('instruct') || this.FORCE_PROMPT) {
       this.isChatCompletion = false;
       this.isChatGptModel = false;
     }
@@ -128,9 +131,13 @@ class OpenAIClient extends BaseClient {
       this.modelOptions.stop = stopTokens;
     }
 
-    if (this.options.reverseProxyUrl) {
-      this.completionsUrl = this.options.reverseProxyUrl;
-      this.langchainProxy = this.options.reverseProxyUrl.match(/.*v1/)[0];
+    if (reverseProxy) {
+      this.completionsUrl = reverseProxy;
+      this.langchainProxy = reverseProxy.match(/.*v1/)?.[0];
+      !this.langchainProxy &&
+        console.warn(`The reverse proxy URL ${reverseProxy} is not valid for Plugins.
+The url must follow OpenAI specs, for example: https://localhost:8080/v1/chat/completions
+If your reverse proxy is compatible to OpenAI specs in every other way, it may still work without plugins enabled.`);
     } else if (isChatGptModel) {
       this.completionsUrl = 'https://api.openai.com/v1/chat/completions';
     } else {
@@ -185,7 +192,7 @@ class OpenAIClient extends BaseClient {
         this.encoding = model.includes('instruct') ? 'text-davinci-003' : model;
         tokenizer = this.constructor.getTokenizer(this.encoding, true);
       } catch {
-        tokenizer = this.constructor.getTokenizer(this.encoding, true);
+        tokenizer = this.constructor.getTokenizer('text-davinci-003', true);
       }
     }
 
diff --git a/api/app/clients/PluginsClient.js b/api/app/clients/PluginsClient.js
index 15d81e81f7..919f1b8131 100644
--- a/api/app/clients/PluginsClient.js
+++ b/api/app/clients/PluginsClient.js
@@ -34,7 +34,11 @@ class PluginsClient extends OpenAIClient {
     this.isGpt3 = this.modelOptions?.model?.includes('gpt-3');
 
     if (this.options.reverseProxyUrl) {
-      this.langchainProxy = this.options.reverseProxyUrl.match(/.*v1/)[0];
+      this.langchainProxy = this.options.reverseProxyUrl.match(/.*v1/)?.[0];
+      !this.langchainProxy &&
+        console.warn(`The reverse proxy URL ${this.options.reverseProxyUrl} is not valid for Plugins.
+The url must follow OpenAI specs, for example: https://localhost:8080/v1/chat/completions
+If your reverse proxy is compatible to OpenAI specs in every other way, it may still work without plugins enabled.`);
     }
   }
 
diff --git a/api/app/clients/specs/OpenAIClient.test.js b/api/app/clients/specs/OpenAIClient.test.js
index 3dd3694851..6dc4123a6a 100644
--- a/api/app/clients/specs/OpenAIClient.test.js
+++ b/api/app/clients/specs/OpenAIClient.test.js
@@ -1,3 +1,4 @@
+require('dotenv').config();
 const OpenAIClient = require('../OpenAIClient');
 
 jest.mock('meilisearch');
@@ -39,6 +40,54 @@ describe('OpenAIClient', () => {
       expect(client.modelOptions.model).toBe(model);
       expect(client.modelOptions.temperature).toBe(0.7);
     });
+
+    it('should set apiKey and useOpenRouter if OPENROUTER_API_KEY is present', () => {
+      process.env.OPENROUTER_API_KEY = 'openrouter-key';
+      client.setOptions({});
+      expect(client.apiKey).toBe('openrouter-key');
+      expect(client.useOpenRouter).toBe(true);
+      delete process.env.OPENROUTER_API_KEY; // Cleanup
+    });
+
+    it('should set FORCE_PROMPT based on OPENAI_FORCE_PROMPT or reverseProxyUrl', () => {
+      process.env.OPENAI_FORCE_PROMPT = 'true';
+      client.setOptions({});
+      expect(client.FORCE_PROMPT).toBe(true);
+      delete process.env.OPENAI_FORCE_PROMPT; // Cleanup
+      client.FORCE_PROMPT = undefined;
+
+      client.setOptions({ reverseProxyUrl: 'https://example.com/completions' });
+      expect(client.FORCE_PROMPT).toBe(true);
+      client.FORCE_PROMPT = undefined;
+
+      client.setOptions({ reverseProxyUrl: 'https://example.com/chat' });
+      expect(client.FORCE_PROMPT).toBe(false);
+    });
+
+    it('should set isChatCompletion based on useOpenRouter, reverseProxyUrl, or model', () => {
+      client.setOptions({ reverseProxyUrl: null });
+      // true by default since default model will be gpt-3.5-turbo
+      expect(client.isChatCompletion).toBe(true);
+      client.isChatCompletion = undefined;
+
+      // false because completions url will force prompt payload
+      client.setOptions({ reverseProxyUrl: 'https://example.com/completions' });
+      expect(client.isChatCompletion).toBe(false);
+      client.isChatCompletion = undefined;
+
+      client.setOptions({ modelOptions: { model: 'gpt-3.5-turbo' }, reverseProxyUrl: null });
+      expect(client.isChatCompletion).toBe(true);
+    });
+
+    it('should set completionsUrl and langchainProxy based on reverseProxyUrl', () => {
+      client.setOptions({ reverseProxyUrl: 'https://localhost:8080/v1/chat/completions' });
+      expect(client.completionsUrl).toBe('https://localhost:8080/v1/chat/completions');
+      expect(client.langchainProxy).toBe('https://localhost:8080/v1');
+
+      client.setOptions({ reverseProxyUrl: 'https://example.com/completions' });
+      expect(client.completionsUrl).toBe('https://example.com/completions');
+      expect(client.langchainProxy).toBeUndefined();
+    });
   });
 
   describe('selectTokenizer', () => {
diff --git a/api/server/services/ModelService.js b/api/server/services/ModelService.js
index f2ba7d94c3..41d4290ffb 100644
--- a/api/server/services/ModelService.js
+++ b/api/server/services/ModelService.js
@@ -28,7 +28,7 @@ const fetchOpenAIModels = async (opts = { azure: false, plugins: false }, _model
   }
 
   if (reverseProxyUrl) {
-    basePath = reverseProxyUrl.match(/.*v1/)[0];
+    basePath = reverseProxyUrl.match(/.*v1/)?.[0];
   }
 
   const cachedModels = await modelsCache.get(basePath);