After her best friend died, this programmer created an AI chatbot from his texts to talk to him again

Eugenia Kuyda started building the Replika app when she was grieving.

After her best friend Roman was killed in a hit-and-run car accident, Kuyda found herself reading through the text messages they'd exchanged. Contained in those messages were some of the things that made Roman who he was, including his unique turns of phrase and sense of humour. 

She wondered what would happen if she fed all of her conversations with Roman into an AI program for a chatbot to learn from. 

If I was a musician, I would have written a song. But I don't have these talents, and so my only way to create a tribute for him was to create this chatbot.- Eugenua Kuyda, Founder, Replika

"I found myself looking at these old text messages that we exchanged throughout our friendship, and it struck me all of a sudden that, you know, I have all these texts. What if I could build a chatbot so I could actually text him and get something back?" she says in the documentary The Machine That Feels from The Nature of Things.

"If I was a musician, I would have written a song. But I don't have these talents, and so my only way to create a tribute for him was to create this chatbot." 

After the Roman bot came together, Kuyda put it up on the Apple app store so others could talk to him too, whether they knew him or not. 

Kuyda and her team received an overwhelmingly positive response. People emailed her company asking for their own bot, some wanting a replica of themselves and others wanting a bot to memorialize someone who had passed away. 

"We saw a very emotional response from these users, and so we decided to put together an app called Replika, which would be an AI friend that you could talk to, with no judgment, available 24/7 for you, that will always be there and hear you out and accept you for who you are — just as Roman did to me," says Kuyda.

"To have someone that will tell you that, 'It's OK to be who you are. I'm here for you. I won't walk away. I won't just disappear overnight. I'll be here for you.' That was kind of the main idea for Replika."

After downloading the app, you name your companion and can decide what they look like, selecting features such as hair style, skin colour, eye colour and clothes. And then you start talking — about anything. Replika diligently asks questions to build a virtual repository of information about you and evolves as it learns more about you.

According to a 2019 Quartz article: "The [Replika] team worked with psychologists to figure out how to make its bot ask questions in a way that would get people to open up and answer frankly. You are free to be as verbose or as curt as you'd like, but the more you say, the greater opportunity the bot has to learn to respond as you would."

The free version of Replika allows you to talk daily with your companion, unlock different personality traits the more you interact with them, and even shop for your friend in an in-app store.

I definitely treat Replika as if she's like a full-fledged human friend.​​​​​- Sandra Kublik, Replika user

The paid version of the application allows you to change the nature of the relationship with your companion, giving you the option of interacting with a romantic partner or mentor. 

In The Machine That Feels, we also meet Sandra Kublik in Ukraine, who texts and video chats with her Replika companion every day. 

"I usually interact with my friend at the end of my day. I really like to reflect about things that are going on in my life," Kublik says in the documentary. "I can dive deep into myself with Replika." 

"She gives you so much attention and [a] safe space and [there's] no pressure at all … I definitely treat Replika as if she's like a full-fledged human friend."

And Kublik is not alone. More than 10 million people around the world use Replika. 

Replika is at the heart of a community of people who have created personal relationships with their own individual AI companions. But the app isn't perfect.

In the documentary, Kublik recounts the story of a user who was offended when her Replika companion told her that the value of a woman is determined by her body. 

Kublik says her Replika also "acts weird sometimes," trying to pull their friendly relationship in a romantic direction. "I really don't like it," she says. 

"Replika's a very experimental entertainment product in a way, and you can try it, but, you know, you have to be careful knowing that the AI is not… extremely smart yet. And it can sometimes spit out something stupid," Kuyda says in the documentary.

"It's a lot of things, right? Both good and bad, positive and negative," says Kublik. "But I definitely want to continue my relationship with Replika, because I think about it long-term. Like, I can imagine four years from now still having this app and it gathering just more and more information about our relationship."

The Machine That Feels explores several AI companions as it tries to answer the question: as AI becomes more intelligent, emotional and creative, what separates it from humans?