How can I find API (json data) for cryptocoins current ask/high/low/average price. Is there any website that provides that ticker information for all coins.
For example BTC/LTC ticker info is available in https://btc-e.com/api/2/ltc_btc/ticker
CoinGecko has a free and public cryptocurrency API to obtain crypto prices from exchanges. It currently covers over 7000+ coins from 400+ exchanges.
You can fetch individual ticker data for an exchange with this endpoint for example https://api.coingecko.com/api/v3/exchanges/binance/tickers
Im not able to comment, thats why I am answering it, in addition to reiven's answer. Bitcoinwisdom is indeed a very good site to watch the BTC trend, and you can watch different markets against different currencies. However, there are even more markets you can see. For example the site for the Blackcoin vs Bitcoin market on mintpal is the following. The Dogecoin vs Bitcoin on crypsty is this one.