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Tutorial: How to Create Chatbots using Large Language Models (LLMs)?

Deepak Joshi
By Deepak Joshi | Last Updated on January 26th, 2024 9:09 am

Chatbots have become an integral part of the digital experience, offering seamless interaction and support to users across various platforms. The integration of Large Language Models (LLMs) like GPT-3 has further enhanced their capabilities, making them more intuitive and efficient in understanding and responding to human language.

The recent advancements in open-source LLMs, such as Blenderbot and Hugging Face's Model Hub, as highlighted in the video below have opened new avenues for developers. These models, trained on diverse and extensive datasets, enable the creation of chatbots that not only understand complex queries but also respond in a conversational and contextually relevant manner.

In this guide, we delve into the process of building a chatbot using these advanced LLMs. Whether you're a novice or an experienced developer, this guide will provide you with the insights and steps needed to develop a sophisticated chatbot.






Installation and Setup

To begin, install the Hugging Face Transformers library, a cornerstone for working with LLMs. For Python users, this can be done using pip:

pip install transformers

This setup is crucial for accessing a range of pre-trained models suitable for chatbot development. The Hugging Face Transformers Library Documentation provides a comprehensive guide for getting started with these models.

In addition to the Transformers library, it's important to ensure your Python environment is properly configured. Python is a versatile language that forms the backbone of many chatbot applications, including those using LLMs. Verify your Python installation and consider updating it to the latest version for optimal performance:

python --version
python -m pip install --upgrade pip

For a more streamlined and isolated development experience, setting up a virtual environment is recommended. This approach helps in managing dependencies specific to your chatbot project:

python -m venv chatbot-env
source chatbot-env/bin/activate  # On Windows use `chatbot-env\Scripts\activate`

Once your environment is prepared and the necessary libraries are in place, you're all set to embark on the journey of building a sophisticated chatbot using the power of Large Language Models.

Choosing and Loading Your Model

Select a model like GPT-2, known for its efficiency in generating human-like text. Load the model using the following Python code:

from transformers import GPT2LMHeadModel, GPT2Tokenizer

tokenizer = GPT2Tokenizer.from_pretrained("gpt2")
model = GPT2LMHeadModel.from_pretrained("gpt2")

This step is key to harnessing the power of LLMs for your chatbot. To explore more about GPT-2 and its capabilities, OpenAI's blog on GPT-2 offers valuable insights.

Besides GPT-2, you can consider exploring other models that might be more suited to your specific chatbot requirements. For instance, Blenderbot, available through the Hugging Face Transformers library, is an excellent choice for chatbots that require more nuanced and contextually aware conversational abilities. It's designed to handle a wide range of conversational scenarios, making it a versatile option for various chatbot applications.

To load Blenderbot, you would use a similar approach as with GPT-2. Here’s how you can initialize Blenderbot in your Python environment:

 from transformers import BlenderbotTokenizer, BlenderbotForConditionalGeneration

blenderbot_tokenizer = BlenderbotTokenizer.from_pretrained("facebook/blenderbot-400M-distill")
blenderbot_model = BlenderbotForConditionalGeneration.from_pretrained("facebook/blenderbot-400M-distill")

By choosing the right model, you can significantly enhance the effectiveness and user experience of your chatbot. Whether it's GPT-2 for its text generation prowess or Blenderbot for its conversational context handling, the choice depends on the specific needs and goals of your chatbot project.

Building the Chatbot Core

Generate responses using the model. Here's a simple implementation for responding to user queries:

input_text = "Who won the world series in 2020?" 
input_ids = tokenizer.encode(input_text, return_tensors='pt')

output = model.generate(input_ids, max_length=50)
output_text = tokenizer.decode(output[:, input_ids.shape[-1]:][0], skip_special_tokens=True)


This code forms the backbone of your chatbot's conversational abilities. For a practical example of a chatbot project using an open-source LLM, you can refer to this GitHub repository on BlenderBot.

In building the core of your chatbot, it's essential to focus on how the model processes and responds to input. The above implementation with GPT-2 showcases a straightforward approach to generating text. However, if you're using a model like Blenderbot, the approach might slightly differ due to its unique conversational abilities.

For instance, Blenderbot is designed to handle more extended conversations, keeping track of the context. This feature can be particularly useful in creating chatbots that need to maintain a coherent conversation over multiple exchanges. Here's an example of how you might set up a response generation with Blenderbot:

conversation_input = "What's the weather like today?"
blenderbot_input_ids = blenderbot_tokenizer.encode(conversation_input, return_tensors='pt')

blenderbot_output = blenderbot_model.generate(blenderbot_input_ids, max_length=100)
blenderbot_output_text = blenderbot_tokenizer.decode(blenderbot_output[0], skip_special_tokens=True)


In this implementation, Blenderbot can provide more contextually relevant responses, making the chatbot interaction more engaging and natural. Whether you choose GPT-2 for its text generation capabilities or Blenderbot for its conversational context handling, the core of your chatbot should be built around the strengths of the selected model to ensure the best user experience.

Developing the Chatbot Backend

Once you have your chatbot's core functionalities in place, the next step is to deploy these capabilities on a backend server. This section will guide you through using Flask, a lightweight Python web framework, for this purpose. Additionally, we'll introduce NGROK, a tool that allows you to make your local server accessible over the internet.

Flask is an excellent choice for deploying Python applications due to its simplicity and flexibility. To get started, install Flask using pip:

pip install Flask

Next, create a basic Flask application. This application will serve as the backend for your chatbot:

from flask import Flask, request, jsonify
app = Flask(__name__)

@app.route('/chat', methods=['POST'])
def chat():
    user_input = request.json['message']
    input_ids = tokenizer.encode(user_input, return_tensors='pt')
    output = model.generate(input_ids, max_length=50)
    response = tokenizer.decode(output[0], skip_special_tokens=True)
    return jsonify({'response': response})

if __name__ == '__main__':

This code sets up a basic Flask server with a single endpoint '/chat' that accepts POST requests. When a user sends a message, the chatbot processes it and returns a response.

To make your local Flask server accessible over the internet, NGROK can be used. This is particularly useful for testing and development purposes. First, download and install NGROK from their website.

Once installed, you can expose your local server to the internet by running:

ngrok http 5000

This command tells NGROK to forward traffic from a public URL to your local server running on port 5000 (the default Flask port).

With NGROK running, your Flask server is now accessible over the internet, allowing you to test and interact with your chatbot from any device.

By setting up Flask and using NGROK, you've created a robust backend for your chatbot, capable of handling requests from users anywhere in the world.

Creating the Chat Interface

The chat interface depends on your target platform, be it a website, mobile app, or social media. The design should focus on user-friendliness and seamless integration of the chatbot.

When designing the chat interface, consider the user journey and how the chatbot will fit into this experience. The interface should be intuitive, allowing users to interact with the chatbot effortlessly. This includes clear input fields, readable text, and responsive design elements that adapt to different devices.

In addition to the visual aspects, the backend integration is crucial. This involves connecting your chatbot model to the interface so that it can receive user inputs and send back responses. If you're using a model like GPT-2 or Blenderbot, ensure that the backend can handle the model's processing requirements. For instance, you might need to set up APIs that allow your chatbot to communicate with the model server, especially if the processing is done remotely.

Here’s a basic example of how you might integrate the chatbot model with a web interface using Flask, a lightweight Python web framework:

from flask import Flask, request, jsonify
app = Flask(__name__)

@app.route('/chat', methods=['POST'])
def chat():
    user_input = request.json['message']
    input_ids = tokenizer.encode(user_input, return_tensors='pt')
    output = model.generate(input_ids, max_length=50)
    response = tokenizer.decode(output[0], skip_special_tokens=True)
    return jsonify({'response': response})

if __name__ == '__main__':

This Flask application creates a simple API endpoint for your chatbot. When a user sends a message through the chat interface, the message is processed by the model, and a response is generated and returned.

Remember, the key to a successful chatbot interface is not just about aesthetics but also about functionality and responsiveness. Your chatbot should be able to handle queries efficiently and provide responses in a way that feels natural and engaging to the user.

Chatbot Interaction Process

Understanding the chatbot interaction process is crucial for creating a responsive and intelligent chatbot. This section will describe how to encode conversation history, fetch user prompts, tokenize inputs, generate responses, and update the conversational context.

For a chatbot to be effective, it needs to remember the context of the conversation. This is achieved by encoding the conversation history. Here's how you can implement this:

# Assuming 'conversation_history' holds the ongoing conversation
input_text = conversation_history + user_input
input_ids = tokenizer.encode(input_text, return_tensors='pt')

This approach appends the user's input to the existing conversation history, allowing the model to generate responses based on the entire conversation, not just the latest message.

Once the conversation history is encoded, the chatbot needs to fetch user prompts and generate appropriate responses. Here's an example using GPT-2 or Blenderbot:

output = model.generate(input_ids, max_length=100)
response = tokenizer.decode(output[0], skip_special_tokens=True)
conversation_history += response  # Update conversation history with the bot's response

This code generates a response based on the user's input and the conversation history, then updates the conversation history with the chatbot's response.

It's important to continuously update the conversational context to maintain a coherent and relevant dialogue. This involves appending the chatbot's responses to the conversation history:

conversation_history += f"User: {user_input}\nBot: {response}\n"

This code snippet ensures that both the user's input and the chatbot's response are added to the conversation history, maintaining the flow and context of the conversation.

By implementing these steps, your chatbot will be able to handle conversations in a more human-like and context-aware manner, leading to a more engaging and satisfying user experience.

Testing and Debugging

Testing and debugging are critical steps in the development of a chatbot. This section provides guidance on how to effectively test your chatbot and troubleshoot common issues.

Testing your chatbot ensures that it responds as expected in various scenarios. A popular tool for testing APIs, including chatbot backends, is Postman. Here's a basic guide on how to use Postman for testing your chatbot:

  1. Install and open Postman.
  2. Create a new request and set the method to 'POST'.
  3. Enter your chatbot's endpoint URL. If you're using NGROK, this will be the NGROK URL.
  4. In the 'Body' tab, select 'raw' and choose 'JSON' as the format.
  5. Type a JSON object with a key for your message, like {"message": "Hello, chatbot!"}.
  6. Send the request and observe the response.

This process allows you to simulate user inputs and receive responses from your chatbot, helping you verify its functionality.

During testing, you might encounter various issues. Here are some common problems and tips on how to resolve them:

  • Chatbot Not Responding: Ensure your server is running and accessible. Check for any errors in the console where your Flask app is running.
  • Unexpected Responses: Verify that your model is correctly processing the input. Check the conversation history encoding to ensure it's being updated correctly.
  • Errors in Code: Look for syntax or logical errors in your Python code. Use debugging tools or print statements to trace the flow of your program.

Remember, debugging is an iterative process. It often involves identifying the problem, making changes, and retesting until the issue is resolved.

By following these testing and debugging steps, you can enhance the reliability and performance of your chatbot, ensuring a smooth user experience.

Advantages and Disadvantages of Using LLMs

LLMs offer superior context understanding and support multiple languages, making them ideal for global customer interaction. However, they can be computationally expensive and sometimes unpredictable in their responses. Listed here are some of the advantages and disadvantages of using LLMs.


  • Superior Context Understanding: LLMs like GPT-3 and GPT-4 are renowned for their ability to understand and generate contextually relevant responses. This capability makes interactions with chatbots more natural and human-like.
  • Multilingual Support: These models are often trained on diverse datasets, enabling support for multiple languages. This is particularly beneficial for businesses aiming to provide global customer support.
  • Continuous Learning and Improvement: LLMs can learn from interactions, improving their responses and accuracy over time. This self-improvement aspect makes them increasingly effective for chatbot applications.
  • Flexibility and Scalability: LLMs offer a high degree of flexibility in terms of deployment and scalability, catering to various business sizes and needs.
  • Real-Time Learning Capabilities: Some LLMs, like the ones demonstrated in Blenderbot, have capabilities for real-time learning and adaptation. This means they can adjust their responses based on the ongoing conversation, providing a more dynamic and engaging interaction.
  • Customization and Personalization: LLMs allow for a high degree of customization. You can fine-tune these models to suit specific industry needs or conversational tones, making your chatbot more aligned with your brand voice and customer expectations.


  • Computational Expenses: Advanced LLMs require significant computational resources, which can be a barrier for smaller organizations or individual developers.
  • Predictability Issues: While generally reliable, LLMs can sometimes generate unpredictable or inappropriate responses, posing a challenge for consistent quality in user interactions.
  • Data Privacy Concerns: Despite being a more private option than API-based models, local execution of LLMs still presents potential data privacy challenges that need careful management.
  • Resource Intensiveness: The training and maintenance of LLMs can be resource-intensive, requiring ongoing effort and expertise.
  • Integration Complexity: Integrating LLMs into existing systems or platforms can sometimes be complex, requiring a good understanding of both the model and the platform.
  • Ongoing Maintenance: LLMs, especially those that are continuously learning, require regular updates and maintenance to ensure they remain effective and relevant.


Building a chatbot with LLMs is both challenging and rewarding. While there are hurdles to overcome, the benefits of improved customer engagement and operational efficiency are significant. This tutorial sets you on a path to explore the exciting world of chatbot development using LLMs.

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Deepak Joshi

Content Marketing Specialist at Appy Pie