For the marketing lots of forex brokers claim to offer spreads from 0 pips, but practically who is the forex broker with the lowest spread ?

Spreads at 0 being an exceptional situation, it would be more accurate to check what is the historical average spread, with Lmax Global for example, we can see on the home page (on left side) https://www.lmax.com/professional a chart displaying the average spread for all currency pairs; on 15th April it was 0.19 pips on eur/usd, 0.2 on usd/jpy and 0,79 on gbp/jpy.

Forex brokers with higher spreads includes the commission in the spread, but this is not the case for forex brokers with the lowest spreads, the commission is charged additionally for an average of 40 $ per million traded. Lmax standard commission is 25 $ per million, making him the cheapest forex broker in terms of spread + commission for a standard client. It is even possible to get 23 $ per million with a reduced minimum deposit through our special partnership with Lmax;( check out our special deal ) with these conditions, combined with the Lmax Global strong reputation and liquidity it is quite impossible to trade forex in better conditions.
This article might be also helpful on the criteria to choose a reliable forex broker.