There is no official WhatsApp API. Here is a simple python class which satisfies the need.

emoji.json

{
	":laughing:" : ":-d", 
	":neutral_face:" : ":-|", 
	"stuck_out_tongue:" : ":-p", 
	":heart:" : "<3", 
	":simple_smile:" : ":-)", 
	":worried:" : ":-(", 
	":-1:" : "(n)", 
	":thumbsup:" : "(y)", 
	":wink:" : ";-)"
}

whatsapp.py

# SWAMI KARUPPASWAMI THUNNAI

#============================================================
# Simple yet Hackable! WhatsApp API [UNOFFICIAL] for Python3
# Note: The author gives permission to use it under Apache2.0
#============================================================

import time
import datetime as dt
import json
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.ui import WebDriverWait   
        

class WhatsApp:
    """
    This class is used to interact with your whatsapp [UNOFFICIAL API]
    """
    emoji = {} # This dict will contain all emojies needed for chatting
    browser = webdriver.Chrome()
    
    # This constructor will load all the emojies present in the json file and it will initialize the webdriver
    def __init__(self,wait,screenshot=None):
        self.browser.get("https://web.whatsapp.com/")
        # emoji.json is a json file which contains all the emojis
        with open ("emoji.json") as emojies:
            self.emoji = json.load(emojies) # This will load the emojies present in the json file into the dict        
        time.sleep(wait)
        if screenshot != None:
            self.browser.save_screenshot(screenshot) # This will save the screenshot to the specified file location
        
    # This method is used to send the message to the individual person or a group
    # will return true if the message has been sent, false else
    def send_message(self,name,message):
        message = self.emojify(message) # this will emojify all the emoji which is present as the text in string
        search = self.browser.find_element_by_class_name("input-search")
        search.send_keys(name+Keys.ENTER) # we will send the name to the input key box
        current_time = time.time()
        while True:
            try:
                send_msg = self.browser.find_element_by_class_name("input")
                send_msg.send_keys(message+Keys.ENTER) # send the message
                return True
            except Exception as e:
                print(e)
            new_time = time.time()
            elapsed_time = new_time - current_time
            if elapsed_time > 30:
                return False
            
    # This method will count the no of participants for the group name provided
    def participants_for_group(self,group_name):
        search = self.browser.find_element_by_class_name("input-search")
        search.send_keys(group_name+Keys.ENTER) # we will send the name to the input key box
        current_time = time.time()
        while True:
            try:
                click_menu = self.browser.find_element_by_css_selector("header.pane-header:nth-child(2) > div:nth-child(2) > div:nth-child(1) > div:nth-child(1) > span:nth-child(1)")
                click_menu.click()
                participants_css_selector = "div.animate-enter2:nth-child(4) > div:nth-child(1) > div:nth-child(1) > div:nth-child(2)"
                participants_count = self.browser.find_element_by_css_selector(participants_css_selector).text
                if "256" in participants_count:
                    return participants_count
                else:
                    time.sleep(1)
            except Exception as e:
                print(e)
            new_time = time.time()
            elapsed_time = new_time - current_time
            if elapsed_time > 100:
                return "NONE" 
    
    # get the status message of a person 
    # TimeOut is approximately set to 10 seconds
    def get_status(self,name,timeout=10):
        search = self.browser.find_element_by_class_name("input-search")
        search.send_keys(name+Keys.ENTER) # we will send the name to the input key box
        start_time = dt.datetime.now()
        while True:
            try:
                click_menu = self.browser.find_element_by_css_selector("header.pane-header:nth-child(2) > div:nth-child(2) > div:nth-child(1) > div:nth-child(1) > span:nth-child(1)")
                click_menu.click()
                # This is the css selector for status
                status_selector = "div.animate-enter2:nth-child(4) > div:nth-child(2) > div:nth-child(1) > div:nth-child(1) > div:nth-child(1) > span:nth-child(1) > span:nth-child(1)"
                status = self.browser.find_element_by_css_selector(status_selector).text
                # if the status if obtained the length must be greater than 0
                if len(status) > 0:
                    return status
            except Exception as e:
                pass
            end_time = dt.datetime.now()
            elapsed_time = (end_time - start_time).seconds
            if elapsed_time > timeout:
                raise TimeoutError("The response has been TimedOut. You may change the time-out specifying in your args.")
    
    # to get the last seen of the person
    def get_last_seen(self,name,timeout=10):
        search = self.browser.find_element_by_class_name("input-search")
        search.send_keys(name+Keys.ENTER) # we will send the name to the input key box
        start_time = dt.datetime.now()
        last_seen_css_selector = ".chat-subtitle-text"
        while True:
            try:
                last_seen = self.browser.find_element_by_css_selector(last_seen_css_selector).text
                if len(last_seen) > 0:
                    if "click here" in last_seen:
                        pass
                    else:
                        return last_seen
            except Exception as e:
                pass
            
            end_time = dt.datetime.now()
            elapsed_time = (end_time - start_time).seconds
            if elapsed_time > timeout:
                raise TimeoutError("The response has been TimedOut. You may change the time-out specifying in your args.")
     
    # This method is used to emojify all the text emoji's present in the message
    def emojify(self,message):
        for emoji in self.emoji:
            message = message.replace(emoji,self.emoji[emoji])
        return message      
    
    # This method is used to quit the browser
    def quit(self):
        self.browser.quit()