The UK government has said it will accelerate the use of open source software in public services.
Tom Watson MP, minister for digital engagement, said open source software would be on a level playing field with proprietary software such as Windows.
Open source software will be adopted "when it delivers best value for money", the government said.
It added that public services should where possible avoid being "locked into proprietary software".
Licenses for the use of open source software are generally free of charge and embrace open standards, and the code that powers the programs can be modified without fear of trampling on intellectual property or copyright.
According to some in the open source industry, the shift from proprietary standards could save the government £600m a year.
Simon Phipps, chief open source officer for Sun Microsystems, said the UK government's stance was part of a "global wave" of take up for open source in governments.
Open source can help avoid many of the hidden costs of proprietary software - Steve Shine, Ingres
"We waste a fortune on proprietary computer software because of paying for licenses and promises up front and not demanding value," he said.
Mr Phipps said schools, government departments and public services would have a "crucial freedom" because of the choice of whether to pay for support and training when using open source software.
The government's action plan could see a wave of open source software being deployed in areas such as office applications (word processing and spreadsheets), document management and database infrastructure, the backbone of many large-scale IT systems.
Steve Shine, European vice president of Ingres, an open source support vendor, said the government's action plan had "more teeth" than policies being adopted in other countries because the plan was tied into policies regarding how IT managers procure new software.
He said the move had partly been driven by a series of high-profile IT failures in recent years that had relied on proprietary software.
He said: "Open source can help avoid many of the hidden costs of proprietary software such as making organisations re-pay for licenses if they want to shift use of a particular piece of software from one place to another.
"This is irrelevant in the open source world."
Announcing an open source and open standards action plan, the government said it would:
* ensure that the government adopts open standards and uses these to communicate with the citizens and businesses that have adopted open source solutions
* ensure that open source solutions are considered properly and, where they deliver best value for money are selected for government business solutions
* strengthen the skills, experience and capabilities within government and in its suppliers to use open source to greatest advantage
* embed an open source culture of sharing, re-use and collaborative development across government and its suppliers
* ensure that systems integrators and proprietary software suppliers demonstrate the same flexibility and ability to re-use their solutions and products as is inherent in open source.
Government departments will be required to adopt open source software when "there is no significant overall cost difference between open and non-open source products" because of its "inherent flexibility".
Mr Phipps and Mr Shine said they expected a backlash from proprietary software firms.
"I am absolutely certain there have been communications extremely high-up in proprietary vendors with management high up in government," said Mr Shine.
Mr Phipps added: "Measured over the short term traditional vendors will cut prices back, end load contacts and do everything to appear cheaper.
"But the real value with open source comes from giving users a new flexibility."
He said the widespread adoption of open source software in public services could also have a knock on effect to the ordinary consumer.
"It's already happening to significant extent in the UK. Lots of homes are using Firefox and OpenOffice.org.
"It is becoming acceptable and expected."