Thousands of passengers could save money on rail fares as "split tickets" become more common, experts predict.
Buying multiple tickets to split one journey into sections can work out to be cheaper than having a single ticket.
Users do not have to change trains, as long as their train stops at the final destination printed on each ticket - but the practice has been "niche".
Booking site Trainline has now released a SplitSave tool to help find cheaper journeys by splitting trips into legs.
"Split tickets" are legal provided that trains stop at ticket destinations.
Travel journalist Simon Calder told BBC News "split ticketing" was not a new concept, but had previously only been carried out by a well-informed group of passengers.
"What we're seeing now is the whole thing moving from the niche to a company through which millions buy tickets," he said.
Previously, passengers could use split ticketing websites such as RailEurope's Pricehack and Split My Fare to check ticket prices.
How it works
The ticket companies' apps are able to find combinations of tickets to save passengers money on most routes across the UK, by automatically splitting the trip into multiple legs.
Passengers buy more than one ticket, rather than a single ticket covering the entire journey.
As long as the train makes a stop at a passenger's split ticket station along the way, they can be on the same train throughout the whole journey.
To buy a ticket from London Paddington to Bristol Temple Meads without splitting the fare could cost up to £112 on Monday morning.
However, buying one ticket from Paddington to Didcot - which is on the same route - and another from Didcot to Bristol would save around a third of the cost of the trip. The practice is legal so long as the train stops as Didcot.
Trainline said other examples of potential savings included one of £80.10 between Manchester Piccadilly and London Euston, and £79.85 between Edinburgh Waverley and London King's Cross.
The Rail Delivery Group (RDG), which represents train operators, called for a reform to the whole rail fares structure, describing the split-ticket feature as a "sticking plaster" solution to a "system in need of major surgery".
Experts say the rules governing how tickets are sold - which date back to 1995 - have not kept pace with technology or how people work and travel.
The rail industry has previously admitted that passengers are not always offered the cheapest fare available due to "long-standing anomalies".
The RDG published a wish list of reforms last year, including allowing ticket prices to be set more flexibly.
Mr Calder said ticket-splitting by large numbers of passengers may speed up rail fare reforms as train companies begin to lose revenue.
"The railway industry says it has been calling for reform for years and I think [ticket splitting] could accelerate that process," he said.
"We're going to see train companies saying to the government: 'We're losing all this money, you've got to help us sort this out.'
"The simple answer is fares reform."
Jacqueline Starr, chief operating officer at RDG, said: "We support any effort to improve how people buy tickets within the current fares structure, but ultimately these are only sticking plaster solutions on a system in need of major surgery.
"Reforms proposed by train operators and backed by consumer groups would deliver a better range of fares for everyone, encouraging people to use the network and generating revenue for government to re-invest back in to improvements in services."
The tool was welcomed by independent watchdog Transport Focus for enabling passengers "to take advantage of cheaper journeys where they are available".
However, the group's chief executive, Anthony Smith, added: "Of course, people shouldn't need tips and tricks to know they are getting the best deal and so we want to see major fares and ticketing reforms coming out of the forthcoming Williams review."