Improving the UX of your website with an intelligent chatbot | AWS Lex

Note: The video series of this blog post is available here.

User Experience is one of the most important concerns in building modern web applications. No matter how feature-rich is your website, if people don’t find it intuitive to use, you will not reach out to your potential customers.

AWS Lex allows users to easily interact with your website using natural language via a conversational chatbot. Your users can chat in voice or in text and use your product services without having to go through complex user interfaces.

As a developer, you don’t have to be a Machine Learning/Deep Learning expert to have a chatbot embedded into the website. AWS Lex provides advance deep learning functionalities and automatic speech recognition techniques out of the box.

In this post, we are going to create a conversational bot that finds weather information as per user’s requests. Following are the technologies that we will be using in this project.

  1. Amazon Lex
  2. Amazon Cognito
  3. AWS Lambda
  4. AWS IAM
  5. Amplify Library
  6. Angular Framework

Please find the github repo related to this post at

Getting the bot ready for training

First, let’s create our bot and get it ready for training. We want our bot to search for weather information when a user has requested it. In this guide, let’s only consider communication via text.

Login to AWS console and Go to AWS Lex

If you haven’t created a bot before select get started and you will be directed to the create bot window.

Creating a Custom Bot

We can either select already created bot or create our custom bot. Let’s select Custom Bot.

Let’s give our bot a name(I named it “WeatherBot”)and fill the other configurations as above image. Since we don’t enable voice select text-based application option. Afterward, click create and you will be presented with a new screen as below.

We need to understand the terminology for our bot in AWS Lex. There are 5 main points to remember.

  1. Intents
  2. Utterances
  3. Slots
  4. Prompts
  5. Fulfillment

Intents are the intentions why someone would use the bot. In our example, someone might want to know the weather of a particular city in the world. We will have an intent called “FindWeather”. We can have more than one intents for the bot. Another intent would be “GreetUser”. Utterances are how a user interacts with the bot stating different phrases. An example utterance can be “How is the weather in Colombo?”

When a user utters a phrase in text or invoice, the bot will match it to a corresponding intent. “How is the weather in Colombo” utterance will be matched to “FindWeather” intent. In order to fulfill the user’s intent, the bot will ask other required questions from the user. These questions are called “Prompts”. Once a user replied to a prompt that will be stored in variables for later use. These variable are called “Slots”. When all the required slots for a intent is collected, the bot will fulfill the intention of the user. The “fulfillment” may involve calling a 3rd party service to search for information, talking to a database, executing some logic in lambda function etc… Our example WeatherBot will talk to OpenWeatherMap API with the user requested city to search for weather information and send it back to the user.

Creating Intents

Click “Create Intent” button to create the first intent for our WeatherBot. Let’s call it “FindWeather” and Add it.

Now let’s add some sample utterances a user might ask. They will help our chatbot to learn about user inputs.

I have added three utterances as shown above. Note that two of those utterances has {City} variable. This is a required slot value for FindWeather intent. We can fill the slot using the user’s utterance itself. “Tell me about the weather” utterance doesn’t have {City} slot involved. So the bot will question the user about the city using a prompt.

In the Slots section, let’s add our City slot. We can define the Prompt message together with that. Our bot can use the intent to get the City slot filled from the user if it didn’t receive it already from the user’s initial utterance.

Our bot requires only one variable to search for the weather. That is the City. Once it is received from the user, the bot will call the action for Fulfillment of the intent.

In our case, let’s call a Lambda function that talks to OpenWeather API to search the weather for the requested City.

Creating the Lambda Function

Let’s use the Serverless Framework to create our lambda function. If you haven’t already installed Serverless Framework please visit this link.

Once you have installed the serverless framework and configure credentials with your AWS account, create a serverless service using below command.

serverless create --template aws-nodejs --path weather-bot

Once creation is completed, change directory into weather-bot folder and open the files in your favorite IDE.


Let’s add a simple function as shown above. I will call it getWeather. The logic of the function lies in the handler.js file.

Lambda logic to obtain weather info from OpenWeatherMap API

I have obtained a free API key from and added it as a query parameter(APPID) in the URL. I extracted the “City” slot value that was taken by the user and passed it in the URL as well. “units” parameter is set to “metric” in order to get temperature values in Celsius.

I also used “axios” npm library to easily send HTTP requests to the server. You may also use the default “http” node module if you prefer. Note how the answer variable is constructed. It is created with string concatenation to form a natural language like the response. This response is returned from the lambda function as a special JSON object. This is required for our bot to read the answer properly. For more information about request/response JSON object template supported by AWS Lex see this link from official documentation.

Alright! Let’s deploy our lambda function using the following command. Before that, don’t forget to install axios library from npm

// First run
npm install axios
// Then run
serverless deploy

Once it is successfully deployed, go back to Lex console and select the lambda function name under the Fulfillment section.

Testing our bot

We have done all the configuration required from our side. Now let’s build the bot and let AWS Lex train its neural network. Once the build is complete we can test our bot.

Once it showed the success message, you can start testing it in the console itself.

The bot further asks a question since we didn’t provide it the city name.

As you can see, our bot successfully connected to OpenWeatherMap API sent us the Weather information for London city.

Adding our bot to the website

Now that we have an awesome bot, we need to add it to our production website so our users can directly interact with it.

Let’s create an angular website and use AWS Amplify library to connect to our WeatherBot securely. We need to install angular CLI and amplify CLI globally and configure amplify to with AWS credentials.

// Install angular cli globallynpm install -g @angular/cli
// Create a new angular projectng new my-bot-website --style=scss --routing
// Install amplify library globally
npm install -g @aws-amplify/cli
// Configure amplify with AWS IAM credentials
amplify configure

In order to communicate with our bot securely, we have to make sure only the logged in user can talk to it. As for the next steps let’s add a Login to the website and then use Amplify out of the box interaction component to connect to our WeatherBot.

Once a user is successfully logged into the application, AWS Cognito assigns him an IAM role. The Permission/Policies for invoking backend services are associated with this role. Since our user will communicate with the AWS Lex Chatbot, we need to provide permission for that authenticated role to call AWS Lex services. You can find the IAM role name that is assigned to logged in user at Cognito Identity Pool configuration.

I’m not going to add those steps in this blog as this post is already lengthy. Instead, let me share the Github URL for the code here.

You can clone the code from the repo and run amplify init to initialize with your AWS resources. To run it on browser use amplify serve

You can use Amplify library itself to host your website along with the bot in an S3 bucket.

I hope someone will find this post useful.


Please follow and like us:

Published by



Hi everyone! I'm Manoj and I love cloud computing. This blog is connected to my Youtube channel where I share my experience in working with popular cloud platforms and new/hot/trending cloud services. Hey if you want to become a cloud computing expert, make sure you've subscribed to my Youtube channel and never miss weekly uploads!

Leave a Reply

Your email address will not be published. Required fields are marked *