"It's 400 per cent growth of revenue in half a year," he said.
"I think it's pretty significant."
Reinartz, who recently made the Forbes 30 under 30 Asia list, believes centralising the company in New Zealand has contributed to its success.
"We're all Kiwis . . . we all sort of think the same way, so our value is of working hard, getting stuff done, understanding that we don't have tons of resource and we can't just delegate everything."
The "can-do attitude" helped the management team work well together, he said.
The company hopes to scale its growth to $1 million monthly revenue within the next two years.
Postr already runs in Indonesia, Germany and Portugal, as well as Australia and New Zealand, and will soon be launching in Singapore, Chile, South Africa, Algeria and Jordan.
It will also be launching apps in developed markets, including the US and Canada.
It currently has more than two million installs, and nearly the same number of registered users. It served close to 500 million ads in a year and will have served over a billion by the end of 2018. It has already given more than 500 terabytes of mobile connectivity to consumers this year.
"It's become quite a sizeable operation."
The team are feeling "excited" about the growth.
"It's like it's finally working, you know? That's the feeling. We've been working very hard."
They are now at a stage where they must figure out how to scale the operation to an even larger size, Reinartz said.
They are working on new products which Reinartz could not say much about, but he said they would be similar to the current app though might not necessarily involve lock screens.
"Early talks with one New Zealand carrier about big data monetisation have been particularly exciting," he said.
"The New Zealand market was a great test run for our global expansion - it's the perfect spot to see how a developed market reacts to a product and this has allowed us to scale across the world.
"We would love to repeat this process with new products we will be launching over the coming year."
Reinartz last year said the phenomenon of "sponsored data" was on the rise, with mobile data being the most sought-after source of connectivity.
People were increasingly unwilling to pay for minutes or SMS, instead using services like WhatsApp and Facebook Messenger to make calls and send texts. Postr gave mobile operators another revenue-raising tool.
People who download Postr's white-label apps get personalised advertising appearing on the lock screen of their cellphone or tablet, where they can either click to engage with it or unlock and use their device as they normally would.
They earn benefits from their telecommunications provider, ranging from 200MBs to 1GB of monthly mobile data, call time or other credits, depending on market conditions and telco offerings.
