That will not work. Each sites API is different. The endpoints are different, query parameters different, required headers different, authentication mechanism different..... You will have to consult the API documentation.

If you need to use the API for many different sites then it might be worth the effort to write generic code that can deal with many sites using a site specific configuration file / options.

API's differ, so you have to consult the documentation to use it correctly. I signed up for the free plan to get an API key https://coinmarketcap.com/api/. The free plan does not allow access to historical data so you will have to pay for that. Here is an example that gets the latest quote for BTC.

apiKey = "your API key"; (* Replace with your key *)
params = <|"Headers" -> {"X-CMC_PRO_API_KEY" -> apiKey, "Accept" -> "application/json"}|>;

The coinmarketcap.com API uses id's to identify symbols, so get the id for BTC

idBTC = URLExecute[
  HTTPRequest[
   "https://pro-api.coinmarketcap.com/v1/cryptocurrency/map?symbol=BTC", params]]

The id for BTC is 1

(*
{"status" -> {"timestamp" -> "2020-02-26T01:49:39.066Z", 
   "error_code" -> 0, "error_message" -> Null, "elapsed" -> 8, 
   "credit_count" -> 1, "notice" -> Null}, 
 "data" -> {{"id" -> 1, "name" -> "Bitcoin", "symbol" -> "BTC", 
    "slug" -> "bitcoin", "is_active" -> 1, "rank" -> 1, 
    "first_historical_data" -> "2013-04-28T18:47:21.000Z", 
    "last_historical_data" -> "2020-02-26T01:44:00.000Z", 
    "platform" -> Null}}
*)

Use that id to get the latest quote

quoteBTC = 
 URLExecute[
  HTTPRequest[
   "https://pro-api.coinmarketcap.com/v1/cryptocurrency/quotes/latest?id=1", params]]

(*
{"status" -> {"timestamp" -> "2020-02-26T01:50:08.193Z", 
   "error_code" -> 0, "error_message" -> Null, "elapsed" -> 19, 
   "credit_count" -> 1, "notice" -> Null}, 
 "data" -> {"1" -> {"id" -> 1, "name" -> "Bitcoin", "symbol" -> "BTC",
      "slug" -> "bitcoin", "num_market_pairs" -> 7786, 
     "date_added" -> "2013-04-28T00:00:00.000Z", 
     "tags" -> {"mineable"}, "max_supply" -> 21000000, 
     "circulating_supply" -> 18237562, "total_supply" -> 18237562, 
     "platform" -> Null, "cmc_rank" -> 1, 
     "last_updated" -> "2020-02-26T01:49:37.000Z", 
     "quote" -> {"USD" -> {"price" -> 9264.46, 
         "volume_24h" -> 4.27441*10^10, 
         "percent_change_1h" -> -0.762424, 
         "percent_change_24h" -> -3.76928, 
         "percent_change_7d" -> -8.34669, 
         "market_cap" -> 1.68961*10^11, 
         "last_updated" -> "2020-02-26T01:49:37.000Z"}}}}}
*)

Sheeba,

I don't think tradingview.com has an API. BTW, the URL in your post is for "Ethan Allen Interiors", not Etherium. You can use the code from my answer to get data for Etherium by using this URL https://coinmarketcap.com/currencies/ethereum/historical-data/?start=20130428&end=20200221.

Not sure what you mean by "in the candlestick chart form as shown in the website". Do you mean visual appearance? If you want to include volume data, change Map[Take[#, 5] &] to Map[Take[#, 6] &] and use TradingChart.

data // Take[#, 40] & // TradingChart

Take a look at this for an introduction to WL.

Can OHLC option be created for BTC? Can we request a developer for the same?