Curl gives response but python does not and the request call does not terminate?

I am trying this following curl request

curl 'https://www.nseindia.com/api/historical/cm/equity?symbol=COALINDIA&series=\[%22EQ%22\]&from=03-05-2020&to=03-05-2021&csv=true' \
-H 'authority: www.nseindia.com' \
-H 'accept: */*' \
-H 'user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) 
Chrome/88.0.4324.182 Safari/537.36' \
-H 'x-requested-with: XMLHttpRequest' \
-H 'sec-gpc: 1' \
-H 'sec-fetch-site: same-origin' \
-H 'sec-fetch-mode: cors' \
-H 'sec-fetch-dest: empty' \
-H 'referer: https://www.nseindia.com/get-quotes/equity?symbol=COALINDIA' \
-H 'accept-language: en-GB,en-US;q=0.9,en;q=0.8' \
-H 'cookie: ak_bmsc=2D5CCD6F330B77016DD02ADFD8BADB8A58DDD69E733C0000451A9060B2DF0E5C~pllIy1yQvFABwPqSfaqwV4quP8uVOfZBlZe9dhyP7+7vCW/YfXy32hQoUm4wxCSxUjj8K67PiZM+8wE7cp0WV5i3oFyw7HRmcg22nLtNY4Wb4xn0qLv0kcirhiGKsq4IO94j8oYTZIzN227I73UKWQBrCSiGOka/toHASjz/R10sX3nxqvmMSBlWvuuHkgKOzrkdvHP1YoLPMw3Cn6OyE/Z2G3oc+mg+DXe8eX1j8b9Hc=; nseQuoteSymbols=[{"symbol":"COALINDIA","identifier":null,"type":"equity"}]; nsit=X5ZCfROTTuLVwZzLBn7OOtf0; AKA_A2=A; bm_mi=6CE0B82205ACE5A1F72250ACDDFF563E~LZ4/HQ257rSMBPCrxy0uSDvrSxj4hHpLQqc8R5JZOzUZYo1OqZg5Q/GOt88XNtMbsWM8bB22vtCXzvksGwPcC/bH2nPFEZr0ci6spQ4GOpCa/TM7soc02HVf0tyDTkmg/ZdLZlWzond4r0vn+QpSB7f3fiVza1Gdx9OaFL1i3rvqe1OKmFONreHEue20PL0hlREVWeLcFM/5DxKArPwzCSopPp62Eea1510iivl7GmY=; nseappid=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJhcGkubnNlIiwiYXVkIjoiYXBpLm5zZSIsImlhdCI6MTYyMDA2MTQ5OSwiZXhwIjoxNjIwMDY1MDk5fQ.YBTQ0MqRayD3QBM3V6zUt5zbRRICkbIhWWNedkDYrdU; bm_sv=C49B743B48F174C77F3DDAD188AA6D87~bm5TD36snlaRLx9M5CS+FOUicUcbVV3OIKjZU2WLwd1PtHYUum7hnBfYeUCDv+5Xdb9ADklnmm1cwZGJJbiBstcA6c5vju53C7aTFBorl8SJZjBN/4ku61oz0ncrQYCaSxkFGkRRY9VMWm6SpQwHXfMsUzc/Qk7301zs7KZuGCY=' \
--compressed 

This gives us the required response (example below)

"Date ","series ","OPEN ","HIGH ","LOW ","PREV. CLOSE ","ltp ","close ","vwap ","52W H","52W L ","VOLUME ","VALUE ","No of trades "
"03-May-2021","EQ","133.00","133.45","131.20","133.05","132.20","132.20","132.21","163.00","109.55",10262391,"1,356,811,541.80",59409

But if I use the following python script to get the data

import requests

headers = {
'authority': 'www.nseindia.com',
'accept': '*/*',
'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.182 Safari/537.36',
'x-requested-with': 'XMLHttpRequest',
'sec-gpc': '1',
'sec-fetch-site': 'same-origin',
'sec-fetch-mode': 'cors',
'sec-fetch-dest': 'empty',
'referer': 'https://www.nseindia.com/get-quotes/equity?symbol=COALINDIA',
'accept-language': 'en-GB,en-US;q=0.9,en;q=0.8','cookie':'ak_bmsc=2D5CCD6F330B77016DD02ADFD8BADB8A58DDD69E733C0000451A9060B2DF0E5C~pllIy1yQvFABwPqSfaqwV4quP8uVOfZBlZe9dhyP7+7vCW/YfXy32hQoUm4wxCSxUjj8K67PiZM+8wE7cp0WV5i3oFyw7HRmcg22nLtNY4Wb4xn0qLv0kcirhiGKsq4IO94j8oYTZIzN227I73UKWQBrCSiGOka/toHASjz/R10sX3nxqvmMSBlWvuuHkgKOzrkdvHP1YoLPMw3Cn6OyE/Z2G3oc+mg+DXe8eX1j8b9Hc=; nseQuoteSymbols=[{"symbol":"COALINDIA","identifier":null,"type":"equity"}]; nsit=X5ZCfROTTuLVwZzLBn7OOtf0; AKA_A2=A; bm_mi=6CE0B82205ACE5A1F72250ACDDFF563E~LZ4/HQ257rSMBPCrxy0uSDvrSxj4hHpLQqc8R5JZOzUZYo1OqZg5Q/GOt88XNtMbsWM8bB22vtCXzvksGwPcC/bH2nPFEZr0ci6spQ4GOpCa/TM7soc02HVf0tyDTkmg/ZdLZlWzond4r0vn+QpSB7f3fiVza1Gdx9OaFL1i3rvqe1OKmFONreHEue20PL0hlREVWeLcFM/5DxKArPwzCSopPp62Eea1510iivl7GmY=; nseappid=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJhcGkubnNlIiwiYXVkIjoiYXBpLm5zZSIsImlhdCI6MTYyMDA2MTQ5OSwiZXhwIjoxNjIwMDY1MDk5fQ.YBTQ0MqRayD3QBM3V6zUt5zbRRICkbIhWWNedkDYrdU; bm_sv=C49B743B48F174C77F3DDAD188AA6D87~bm5TD36snlaRLx9M5CS+FOUicUcbVV3OIKjZU2WLwd1PtHYUum7hnBfYeUCDv+5Xdb9ADklnmm1cwZGJJbiBstcA6c5vju53C7aTFBorl8SJZjBN/4ku61oz0ncrQYCaSxkFGkRRY9VMWm6SpQwHXfMsUzc/Qk7301zs7KZuGCY=',}

params = (
('symbol', 'COALINDIA'),
('series', '/["EQ"/]'),
('from', '30-04-2021'),
('to', '03-05-2021'),
('csv', 'true'),
)

response = requests.get('https://www.nseindia.com/api/historical/cm/equity', headers=headers, params=params)

It gets stuck in the last line.

I am using python3.9 and urllib3.

Not sure what is the problem. This url downloads a csv file from the website.

You must jump through some hoops with Python to get the file you're after. You need to get the request header cookie part right, otherwise you'll keep getting 401 code.

First, you need to get the regular cookies from the authority www.nseindia.com. Then, you need to get the bm_sv cookie from the https://www.nseindia.com/json/quotes/equity-historical.json. Finally, add something that's called nseQuoteSymbols.

Glue all that together and make the request to get the file.

Here's how:

from urllib.parse import urlencode

import requests

headers = {
    'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) '
                  'AppleWebKit/537.36 (KHTML, like Gecko) '
                  'Chrome/88.0.4324.182 Safari/537.36',
    'x-requested-with': 'XMLHttpRequest',
    'referer': 'https://www.nseindia.com/get-quotes/equity?symbol=COALINDIA',
}

payload = {
    "symbol": "COALINDIA",
    "series": '["EQ"]',
    "from": "04-04-2021",
    "to": "04-05-2021",
    "csv": "true",
}

api_endpoint = "https://www.nseindia.com/api/historical/cm/equity?"

nseQuoteSymbols = 'nseQuoteSymbols=[{"symbol":"COALINDIA","identifier":null,"type":"equity"}]; '


def make_cookies(cookie_dict: dict) -> str:
    return "; ".join(f"{k}={v}" for k, v in cookie_dict.items())


with requests.Session() as connection:
    authority = connection.get("https://www.nseindia.com", headers=headers)
    historical_json = connection.get("https://www.nseindia.com/json/quotes/equity-historical.json", headers=headers)
    bm_sv_string = make_cookies(historical_json.cookies.get_dict())

    cookies = make_cookies(authority.cookies.get_dict()) + nseQuoteSymbols + bm_sv_string
    connection.headers.update({**headers, **{"cookie": cookies}})

    the_real_slim_shady = connection.get(f"{api_endpoint}{urlencode(payload)}")
    csv_file = the_real_slim_shady.headers["Content-disposition"].split("=")[-1]
    with open(csv_file, "wb") as f:
        f.write(the_real_slim_shady.content)

Output -> a .csv file that looks like this: