Seven of Poland's publishers behind 26 national and regional newspapers and 11 magazines have joined together to provide access to 42 websites and services.
From today (18 July) readers will see Piano's login icon at the top of each page of the 42 sites. Next month a free trial will be offered, followed by the start of the full Piano subscription system in September.
Readers will pay €4.70 (£3.70) per month or €47 (£36.88) annually for full access to the 42 sites.
This is Piano's third national payment system to be launched in the past 14 months, with Slovakia's joint part-paywall launching in April 2011 and Slovenia's in January 2012. Experiments in joint models are taking place elsewhere with Dutch publishers announcing in April they were uniting to create a digital "kiosk" – likened to Spotify – where readers can buy articles on-demand or as part of a monthly subscription.
Piano, which is not involved in the dutch kiosk model, said it plans to launch in a fourth market by the end of this year.
In a release, the company said "Poland represents Piano's largest market with a population of 39 million people and over 19 million internet users".
Participating publishers can select the amount of content they put behind the group wall. Some publishers provide ad-free versions of their sites, while others offer premium access to content before it is released, plus exclusive material.
The development in Poland will see an increase in the amount of content to be out behind the wall at launch. When Piano was introduced in Slovakia 14 months ago around 5 per cent of the available content was in the system, Tomas Bella, chief executive of Piano, said in the release. In Slovenia 10 per cent was behind the wall from the outset, and Poland's participating publishers are putting between 10 and 15 per cent of media content the other side of the fence.
"Poland allows us to demonstrate how well our system works in larger markets," Bella, who was previously editor-in-chief of Slovakia's biggest news portal, said in the release. "We are already known for our innovation. Now we will prove our innovation is scalable."
Domestic publishers Agora and Murator and four internationally-owned publishers, Swiss-German Ringier Axel Springer, British Media Regionalne, German Polskapresse and Edytor, "will join the growing worldwide paid-content trend with their entrance into the Piano system".
Update 1.45pm: This article initially stated six publishers were on board and 37 sites were part of the scheme. Since issuing a release earlier in the week, Piano Media has updated the figures and there are now seven publishers involved and 42 sites going behind a part-paywall.