Book your train, bus and carpool tickets.

The savings are real, especially last minute. Where a Paris-London ticket booked the day before can easily hit sky-high prices, Snap keeps prices close to those found booking weeks ahead: the advertised discount goes up to 50%.

That's precisely its purpose: filling the empty seats on the least in-demand trains, letting you benefit if your schedule is flexible.

Before jumping in, still compare with the standard fares of the day on Eurostar: in off-peak periods, the gap sometimes narrows.

The downside can be summed up in three words: non-refundable, non-exchangeable. Once your Snap booking is confirmed, you can't change the date, the time, or transfer the ticket to someone else.

You also don't choose your train: if the time slot assigned two days before doesn't suit you, too bad. So you really need to be free for the whole half-day chosen.

Book Snap for a weekend that's already set, or a return trip with no constraints. For an appointment at a fixed time, a regular Eurostar ticket remains the right choice.

Snap's principle is a bet on your flexibility. You choose your travel date and a simple preference: morning or afternoon. Eurostar then assigns you a specific train and tells you the time 48 hours before departure.

In exchange for this unknown, the discount reaches 50% off the standard price on Paris-London, Brussels and Amsterdam.

Booking is only done on snap.eurostar.com, the dedicated site, for departures between the next day and about two weeks ahead. Once on board, your Snap ticket is worth exactly the same as a regular ticket.