Foreign Crypto exchanges may be required to pay GST on the transactions with Indian citizens as the Government is thinking of levying GST at the rate of 18% on transactions with its citizen
There already has been news earlier that the tax department is also exploring the charging of a 2% equalization levy on transactions with overseas/foreign exchanges.
The cost of purchasing the cryptocurrencies such as bitcoin is likely to increase due to the hit of these taxes the government is exploring.
As far as the local crypto exchanges are concerned, the 18% GST is included in the trading fee which is charged from customers. It is similar to stock trading wherein the brokerage charges recovered are inclusive of the GST.
Cryptocurrencies though in India are not illegal but currently they are still not regulated. Non-regulation means you can purchase or sell the cryptocurrencies such as bitcoins but these are not controlled, regulated, or protected by any bank or government.
Government is in the stage of bringing regulatory framework and laws regarding cryptocurrencies. Various taxation angles are also being explored alongside.