In this post, I'll show you how to create a super simple crypto bot with Twilio API and cryptocompare python package.

I'm using poetry for a python project but it's not necessary to use it. What you need is to have python3 and pip.

[Requirements]

Twilio developer account and active phone number
python3
pip
ngrok (https://ngrok.com/download)
mobile phone to send a message

Step 1 Get a phone number

When you login and access to console page(https://console.twilio.com/?frameUrl=/console), you will see the side menu on the page.

Then click Active numbers. If you have a phone number/phone numbers, the page shows a number/numbers you have.
If you don't have a number, you will need to get one number.

Step 2 Create a project

As I mentioned, I use Poetry to create a python project because it allows us to manage a python project as well as a project that is made by yarn or npm (like js project).

https://python-poetry.org/

$poetry new twilio_crypto_bot
$cd twilio_crypto_bot
# install packages like yarn add packageName
$poetry add twilio flask requests cryptocompare

without Poetry

$mkdir twilio_crypto_bot
$cd twilio_crypto_bot
$pip install twilio flask requests cryptocompare

app.py: main python script
CryptoPrice.py: get cryptocurrency price via cryptocompare pypi package

$ touch app.py CryptoPrice.py

Step 3 Write code

Finally, it's time to code to build a simple bot with Twilio API.

The codes are very simple.
Create a router with Flask. In this case, the path is /sms and it will be used for Webhook.

When a user sends a message to the active number, sms_reply function is called.
For example, the user send price btc
First, the function receives 'price btc' as incoming_msg.
If incoming_message includes price, the function convert it into BTC then create a CryptoPrice instance with BTC to get the current price.
Before sending back the message check the return from CryptoPrice's method. If the return is only numeric(technically type is str but the return includes only numbers + .), return True which means the method returns the current price. Otherwise, the bot will send an error message.

app.py

from flask import Flask, request, redirect
from twilio.twiml.messaging_response import MessagingResponse
import CryptoPrice
import requests
import re

app = Flask(__name__)


def check_numeric(s: str):
    pattern = r"^[+-]?[0-9]*[.]?[0-9]+$"
    return (re.match(pattern, s) is not None)


@app.route('/sms', methods=['GET', 'POST'])
def sms_reply():
    incoming_msg = request.values.get('Body', '').lower()
    resp = MessagingResponse()
    msg = resp.message()
    responded = False
    # print(incoming_msg)

    if 'price' in incoming_msg:
        # return cryptocurrency price
        crypto = incoming_msg.replace('price', '').strip().upper()
        cc = CryptoPrice.Crypto(crypto)
        crypto_price = str(cc.get_crypto_price())
        # print(crypto_price)

        if not check_numeric(crypto_price):
            response = crypto_price
        else:
            response = f"the current price of {crypto} is ${crypto_price} from cryptocompare"
        print(response)
        msg.body(response)
        responded = True

    if not responded:
        msg.body('what do you want to know about cryptocurrencies?')

    # print(str(resp))
    return str(resp)


if __name__ == '__main__':
    app.run(debug=True)

CryptoPrice.py

import cryptocompare


class Crypto():
    def __init__(self, crypto_symbol):
        self.crypto_symbol = crypto_symbol

    def get_crypto_price(self):
        result = cryptocompare.get_price(self.crypto_symbol, currency='USD')
        try:
            return result[self.crypto_symbol]['USD']
        except TypeError as error:
            return 'There is not a coin pair for {}-USD.'.format(self.crypto_symbol)


def main():
    test = 'KOJI'
    cc = Crypto(test)

    val = cc.get_crypto_price()
    print(val)


if __name__ == '__main__':
    main()

Step 4 Set Webhook

We are almost there. But need one more step to make the bot work since currently the bot cannot recognize that a user sends a message or not. To solve this, we need to set Webhook.

There are 3 steps to finish this.
First step is to run app.py.

# with poetry
$ poetry run python app.py

# without poetry
$ python app.py

Then we need to use ngrok which we stored in the project folder.

$./ngrok http 5000

If your app.py and ngrok work properly, you will see something like this.

Then copy https address that ngrok shows you.
Access your Twilio console and Phone Numbers > Manage > Active Numbers and click a number you want to user for this bot.

If the console page is switched, scroll down and find out Webhook(placed the bottom)

Fill out your https url like below and click Save botton.

Step 5 Send a message to a bot

Now we are good to go.
Open sms application on your smartphone and send a message to the active number. As you notice, this is very simple bot, so the message must be the following.

[Format]
price cryptocurrency_symbol
cryptocurrency_symbol price

Example
price btc
eth price

If you send a message without price, the bot returns what do you want to know about cryptocurrencies?

Also if you pass non-existing crypto symbol, the bot returns There is not a coin pair for crypto_symbol-USD.

What you can do may be the followings.

add a new commands For example, alert functionality
If you send alert eth > 3000, the bot will send an alert when the price reaches the range.
introduce NLP functionality which means your bot can understand natural message from you. For instance, hey I want to know the current bitcoin price.
Use another API and check up/down then send a funny image/gif. Twilio supports .gif, .jpg, and .png as media.
Also you can set scheduled messages with crypto_symbol.