Is scalping illegal?

Scalping is perfectly legal in any country, although some brokers do not allow it. 

To date, no regulatory body has said that scalping is an illegal way to make money from financial trading.

Scalpers can make substantial profits in a short period of time, which causes a loss for some brokers, which is why they do not allow it. 

Some brokers themselves act as liquidity providers. Those brokers do not like successful scalpers because they cause them to lose money. 

On the other hand, some brokers allow scalping but make the trading environment unfavorable for scalpers. The scalper then gets high spreads (difference between buy and sell price) and often poor execution (slippage). This confuses some traders, and they begin to believe that scalping is illegal.

The fact is that scalping is simply a trading method like any other method, followed by both private and institutional traders. 

Some traders consider scalping as their primary trading method.

Whatever opinion one holds of scalping, it is one of the most profitable strategies in financial trading for which there are no regulatory obligations. 

So, if you want to start scalping, you should find a broker that allows or even favors it. 

Those brokers do exist.