But it also wants to reach out into other parts of the world, and so is now targeting outlets in western Europe, including UK publishers.
The demand is slightly different in western Europe, specifically in English-language markets, Peter Richards, who works in international sales at Piano Media, explained to Journalism.co.uk.
For example, the markets which Piano Media has so far approached in western Europe – including Denmark and the Netherlands – seem to prefer the idea of taking an individual approach, rather than a national model.
There did not seem to be the "collective will to pull together and launch a national model", Richards said.
Piano Media is therefore approaching these markets with a different solution – Piano Solo – which enables a publisher to set up their own independent paywall, without having to reach an arrangement with others.
The Solo product was made available earlier this year, and this week the first publishers, based in Slovakia, signed up to put it into practice.
According to a press release "the three publishers will introduce their new content using a subscription payment meter, significantly increasing the amount of paid content locked by Piano".
Richards said that Solo-related discussions are "in progress" at publishers in Poland and other countries in central Europe, with models expected to be up and running "by the end of June".
And this Solo model is what Piano Media is now also pursuing in the UK market and elsewhere in western Europe, including in Italy, Spain and Belgium.
"Most publishers seem to be open to at least trying a metered paywall some time this year," Richards said. "Maybe not in their full stable, but a portion."
He said in western Europe the company is "in final negotiations with a Belgian publisher", as well as "two Italian publishers". It is also working on "a study for a Spanish publisher".
He predicts that Piano Media will see its first Solo paywall in western Europe in June, and potentially "three or four implementations in western Europe by September".
In the UK around five publishing groups have so far "expressed initial interest", Richards said, which particular interest being shown by regional media groups.
"Large publishing houses in the UK already have a paid-content solution, so our target market is right now regional."
For Piano Media this is a significant step in presenting itself as not just "a central European solution for a national model only", Richards told Journalism.co.uk. This move was supported by its purchase last year of the "technology and associated rights" of company Novosense, which was used to create the Solo system.
According to a release at the time, the idea was to "help individual media quickly monetise their online content, taking advantage of Piano’s existing know how and reducing risks and costs normally associated with a paid-content launch".
The other benefits for publishers, according to Richards, is the way the Solo product "minimises the most common way to go around a paywall, which is deleting cookies".
"If the user deletes cookies we still know who the user is," Richards said.
Piano is also able to benefit on its experience in building existing national paywalls. "We have a lot of data from what other publishers are making money on," he said, adding that there is demand for the "content analysis" Piano offers to help publishers set their paywall parameters.
For example, they can choose between "hardlocking" and putting content or sections behind a wall, giving people a metered allowance which can be different for different content, or a combination of the two.
He added that for Solo paywall models which run "hardlocking" rather than a meter, Piano has "proven that there's no loss of traffic, there's no loss in pageviews".
"If you use the metered part of Solo, depending on the meter setting, there is some loss of traffic. It's hard to avoid pageview loss with the meter. What we're doing with the Solo is trying to have maximum flexibility for the publisher."
While they will still be required to make "a commitment" to Piano, publishers can effectively try out the product on a smaller-scale in the initial stages.
For example, a publisher with many websites could run the paywall on its smaller titles before they push it out across the portfolio. There is also the ability to buy just "the core metering components, without the payment systems, without the call centre, without detailed analytics", Richards said, and test it that way.
The other option is to go to Piano Media for "a detailed technical and content analysis" before choosing to buy the technology.
"We'll tell them where we think the most loyal sections of the site are that could be potentially hardlocked, what the meter settings could be, what their pageview loss would be ... what technical changes they would require.
"So it's not necessarily a full test but it's a lot of knowledge delivered in a detailed report."
"We do see publishers asking for data," Richards said, "and they're willing to pay for it."