26/10/2015 3:31 PM AEDT | Updated 15/07/2016 12:50 PM AEST

New Safety App Thread Created In Memory Of Murdered South Australian Teenager Carly Ryan

Mark Mawson via Getty Images
15 year old girl's face lit up by an iPhone at a bus stop

When an 18-year-old musician struck up an online friendship with Carly Ryan, 15, in 2007, chat rooms and social media were in their infancy.

Online predators were not spoken about, 'catfishing' was not yet a term and for this South Australian teenager, her trust in the boy she'd been chatting to for 18 months led her into the deadly hands of a murderer.

For mother Sonya Ryan, she saw her grief as a choice.

"All of a sudden my daughter was killed by an online predator and it completely annihilated my world," Ryan told The Huffington Post Australia.

"I was left with choice -- to just dissolve, it’s over, or you fight.

"I have made that choice to fight and to do what I feel my daughter would have wanted, to prevent crimes and to find ways to keep people safe.

"She was a really compassionate kid and I feel this is what she would have wanted me to do."

Love ♡ always Miss you everyday #loveyoumore #foreverandever #teamcarly #nevergiveup

Posted by The Carly Ryan Foundation Inc. on Friday, October 16, 2015

The fight began in school classrooms, where Ryan would speak about internet safety.

As demand grew along with the rising popularity of social media, she created The Carly Ryan Foundation and Monday launched an app to keep young people safe.

Ryan said the centre of the app was a question she asked herself:

"What could Carly have possibly used?" Ryan said.

"In a dangerous situation, what could she have used to have discreetly told me where she was and that she was in trouble?"

Thread is officially launched on android! An amazing day in Sydney. Thankyou Google, Kojo & Government of SA #thethreadapp

Posted by The Carly Ryan Foundation Inc. on Sunday, October 25, 2015

Named Thread, the app is a way of discretely checking in with friends and family at the touch of a button, to say you've arrived home safely, or that you made it to sports practice. You can also send a map of where you are or a photo.

Thread also has an alert function, which immediately calls 000 and alerts your chosen contacts, sending your location, or a photo with a photo and your location.

"It's not something that tracks teenagers all the time -- it's something they have to want to use," Ryan said.

"It's using technology to easily connect with the people who love and care about it."

It's free for Android and iPhone and was created by created by digital specialists KOJO with some funding from the South Australian Government.

Download it here.

A screenshot form Thread.