To use any of the Chatfuel modules, you need to have a Facebook account. Using your Facebook account credentials, sign up for Chatfuel at chatfuel.com.
For custom backend service integration with your chat bot, Chatfuel provides a plugin called JSON API. After inserting this plugin into one of the bot's blocks, you'll need to provide a URL of the backend service endpoint. To obtain an endpoint address from Integromat's Chatfuel app, create a new Integromat scenario and insert a Chatfuel module called JSON Listener. Clicking on the module will let you create a new webhook (just give it a name and click Save), which will provide a dedicated URL that can be used to receive messages from your bot.
Copy this URL by clicking the Copy address to clipboard button. Then, go to your Chatfuel bot builder, open the block containing the JSON API and enter the address into the URL field. Also, set the Type field to POST.
Now that your bot knows where to reach Integromat, you can start building a response inside your Integromat scenario. Sending a response is as simple as inserting a JSON Response module in the scenario's data flow. Below is an example scenario which uses filters to send a personalized greeting if a user's first name is available, and a generic greeting otherwise.
With this scenario setup, sending the first name as part of the user attributes from Chatfuel causes the default "Hello, Anonymous" response to instead include the user's first name: