Working script to book a vaccination slot on console as soon as a slot opens up in https://selfregistration.cowin.gov.in/

cowin_vaccination_autobooking.js

// This javascript code will alert you and immediately book the slot whenever a slot opens up on the given date within the given pincodes.

// **** THIS SCRIPT IS TO MAKE NEW BOOKING FOR DOSE 1 OR DOSE 2. IN CASE OF RESCHEDULE, FIRST CANCEL THE BOOKING AND THEN TRY TO BOOK USING THIS SCRIPT. ****
// **** RUN SCRIPT 5 MINUTES BEFORE THE SLOT OPENING TIME. IF THE SESSION IS EXPIRED (EXPIRES IN 10-15 MINUTES), LOG IN AND RERUN THE SCRIPT. ****

// Steps to use
// 1. Update pincodes,age,district_id,beneficiaries,dose,vaccine & vaccine_date. 
// 2. Login to https://selfregistration.cowin.gov.in/
// 3. Right Click on the website
// 4. Click on Inspect
// 5. Switch to the Console Tab on the recently opened Inspect window
// 6. Copy paste the contents of this entire file - cowin_vaccination_autobooking.js
// 8. Press Enter
// 9. This will generate the captcha and show it in a new window. Note the captcha and close the window.
// 10. Within few seconds, A prompt will show on screen asking you to enter the Captcha code. Type in the Captcha as noted.
// 11. It will run every 3 seconds and check for availability of slots. Once available, it will immediately book the slot. Refresh the page once you get the booking confirmation message.

// Change the pincodes as per your city
var pincodes = [202001,202280];

// Change the age as per your requirement
var age = 18; //45,18

// Change the district id as per the city you are living in
var district_id = 623;

// Keep the vaccine as per your need. Currently it will look for both the vaccines.
var vaccines = ["COVISHIELD","COVAXIN","SPUTNIK V"];

// Enter dose = 1 for first dose, dose = 2 for second dose
var dose = 1;

// Change the date to the date of slot booking
var vaccine_date = "07-06-2021";

// Reference id of the person you are booking a slot for. Can find it written beside your name after you log in. 
var beneficiaries = [66119476081580,66229455431599];

// Defined API Host endpoint
var host = "https://cdn-api.co-vin.in/api";

// Variable to keep track of whether slot is booked
var booked = false;

// Authorization token needed to book a slot - No Changes required
var authorizationToken = "Bearer " + sessionStorage.getItem("userToken").match(/"([^"]+)"/)[1];

var sleepNow = (delay) => new Promise((resolve) => setTimeout(resolve, delay))
var trialCounter = 1;

(function () {
  var newscript = document.createElement('script');
  newscript.type = 'text/javascript';
  newscript.async = true;
  newscript.src = 'https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js';
  (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(newscript);
})();

function httpGet(method, theUrl, isPublic=true) {
  var xmlHttp = new XMLHttpRequest();
  xmlHttp.open(method, theUrl, false); 
  
  if(!isPublic)
	xmlHttp.setRequestHeader("authorization", authorizationToken);
  
  xmlHttp.send(null);

  if(xmlHttp.status == 401){
	alert('Your session has been expired. Please Login and rerun the script.');
	location.reload();
  }
  return xmlHttp.responseText;
}

function getCaptcha() {
  var url = host + "/v2/auth/getRecaptcha";
  var data = JSON.parse(httpGet("POST", url,false)).captcha;

  var myWindow = window.open("", "MsgWindow", "width=200,height=100");
  myWindow.document.write(data);
}

async function fetchByDistrict(captcha) {
  if (captcha.length > 0) {
    console.log("Check: ", trialCounter++);
    url = host + "/v2/appointment/sessions/public/calendarByDistrict?district_id=" + district_id + "&date=" + vaccine_date;

    try {
      centers = JSON.parse(httpGet("GET", url)).centers;
    } catch (e) {
      console.log("error");
    }

    for (i in centers) {
      center = centers[i];
      for (j in center.sessions) {
        session = center.sessions[j];
		
		var available_capacity = 0;
		if(dose==1)
			available_capacity = session.available_capacity_dose1;
		else if(dose==2)
			available_capacity = session.available_capacity_dose2;

        if (!booked && session.min_age_limit == age && available_capacity > 0 && vaccines.includes(session.vaccine) && pincodes.includes(center.pincode) && vaccine_date == session.date) {
          console.log("Vaccines available at : ", center.pincode, center.name, center.center_id, available_capacity);

          data = {
            center_id: center.center_id,
            session_id: session.session_id,
            dose: dose,
            slot: session.slots[0],
            beneficiaries: beneficiaries,
            captcha: captcha
          }

          bookSlot(data);
        }
      }
    }
    
    if (!booked) {
      await sleepNow(3000);
      fetchByDistrict(captcha);
    }
  }
}


function bookSlot(data) {
  console.log('Booking Started');
  return $.ajax({
    type: "POST",
    url: host + "/v2/appointment/schedule",
    async: false,
    data: JSON.stringify(data),
    timeout: 10000,
    beforeSend: function (request) {
      request.setRequestHeader("authorization", authorizationToken);
      request.setRequestHeader("Content-Type", "application/json");
    },
    success: function (result) {
      booked = true;
      alert("Your appointment for the vaccine has been booked. \n\nAppointment No: " + result['appointment_confirmation_no']);
	console.log('Booking Success');
    },
    error: function (error) {
	console.log("BOOKING ERROR : ", error.responseText);
    }
  });
}

// Initiate Booking
getCaptcha();
setTimeout(function(){ 
  fetchByDistrict(prompt("Enter Captcha Code below:"));
}, 3000);

Hi Varun,
thank you for this marvelous effort you've put to help people in this time of need. Also, I really appreciate the patient support, immediate bug fixes with code updates as well as warm and courteous behavior you extended towards me while guiding me thoroughly to use these scripts. From my personal experience i completely vouch for their credibility and utility. They have proved extremely helpful in booking slot for my vaccination and all of it seemed effortless. Thanks again Varun...

Thank you so much @digantopaul.. :)

Hi Varun,
is there any way to book only free one?

@klalj86, Not yet.. if you want you can add fee_type: "Free" in the code or only use pincodes with free one..