"There are so many New Zealanders for whom it's [te ao Māori is] a real foreign world," she told the Rotorua Daily Post.
"Ultimately I know it's just an app but truly, this is why I do it.
"In the past, I just took it for granted that most Kiwis would have some understanding of even the most basic pronunciation and customs," she said.
"But teaching workshops I have met lots of Kiwis who have been here for generations that are really estranged from Māori culture and may not even know a Māori person, which blows my mind.
"A lot of them are in very prominent decision-making roles within our society. The decisions that they make really impact Māori communities.
"To me, as a country, we need to be questioning our apathy towards that," Te Whenua added.
It was important to Te Whenua that her app was free and easily accessible, so she made it in a "DIY" process to keep costs down.
Wellington employment lawyer and workplace mediator Sarah Cates was one of the first to download the app.
She told the Rotorua Daily Post it would be useful to her because she often acts for Māori individuals and organisations.
"The app will be a great resource for me to have at my fingertips and help me continue my learning."
Unlike some apps currently available tailored to certain organisations, Tū Tangata is for anyone and not just non-Māori to use, Te Whenua said.
"If you're in a significant position of decision-making that affects outcomes from Māori you must have, as an absolute requirement, an understanding of Māori culture and Māori society.
"That includes the history of our country, the situation that Māori are presently in, customs, etiquette and language."
She said the lack of understanding of te ao Māori among some decision-makers had been highlighted by the likes of the Oranga Tamariki inquiry last year and even the Covid-19 alert levels.
Te Whenua said the Covid-19 recovery, and Matariki this month were good opportunities for New Zealanders to "take stock of what's important to us", so it was fitting for her to launch the app at this time.
