If you could find out exactly when you're going to die... would you want to know?
Based on a 2019 American supernatural horror film called 'Countdown' directed and written by Justin Dec
Disclaimer: This app is for entertainment purposes. Results should not be taken seriously.
At a party, teenager Courtney is convinced by her friends to download Countdown, an app that seemingly predicts how long a user has left to live. Courtney is startled to see it says she only has 3 hours and 22 minutes left to live. After avoiding getting into a car with her drunk boyfriend Evan, Courtney receives a notification stating she has broken the "user agreement". Returning home, she is attacked by an unseen entity and killed as her timer reaches zero. At the same time, Evan crashes his car and a tree branch impales the seat where Courtney would have been sitting.
Quinn Harris, a nurse who works at the hospital where an injured Evan is admitted, lends a supportive ear but dismisses his claims of a supernatural app. Nevertheless, curiosity eventually causes her to download it. She is horrified to learn it says she has only two days left to live. Evan skips his surgery and is informed he has violated the user agreement. He tries to escape the hospital, but is confronted with an apparition of Courtney before being killed by the entity.
When Quinn finds out that Evan has died, she decides to check his phone, which indicates no time left. Due to dismay that she will die in the next day, Quinn declines to go out with her younger sister Jordan and their father. The app informs her she has violated the user agreement. Shortly afterward, her boss Dr. Sullivan sexually harasses her and thwarts her attempt to report his offense to her supervisor. When Quinn researches the app, she finds that similar deaths have supposedly occurred involving other app users, but the public generally considers them to be fake. She attempts to buy a new phone, but finds that Countdown has downloaded itself onto it.
After being attacked by a demonic figure, she meets a young man named Matt, whose Countdown states he will die in 18 hours. Together, they learn that the user agreement is broken if the user tries to change their fate: Quinn's trip with her family and Matt taking a train ride, which they both canceled, should have resulted in their deaths. At work, Quinn learns Sullivan has tricked the staff into thinking she sexually harassed him, resulting in her suspension. On her time off, she and Matt consult a priest named Father John, who informs them that the app is linked to a demon named Ozhin who was originally summoned by a Roma woman who told a prince when he would die. Cell phone salesman Derek hacks into the app code and identifies that Jordan was meant to die shortly before Quinn, then adds several decades to her, Jordan's, and Matt's lives. However, while Matt and Quinn are spending the night together, the entity takes the form of Matt and attacks Quinn. Then their countdowns, including Jordan's, reset to their original lifespans, much to their shock and horror.
Jordan receives a notification of her countdown changing to the original lifespan and is then terrorized by a demonic form of her and Quinn's deceased mother. Quinn and Matt collect her and return to Father John, who theorizes the curse can be broken if someone dies before their countdown ends or lives for even a single second afterwards. They prepare a warding circle in an attempt to delay Ozhin. The demon arrives and manages to lure them outside, killing Matt and wounding Jordan. Quinn rushes Jordan to the hospital; once there, she realizes she can kill Sullivan before his allotted time and end the curse. She attempts to attack him, but he is saved by Ozhin, who simultaneously prepares to kill Jordan on time. However, Quinn purposefully overdoses on drugs, sacrificing herself before her timer ends and proving the app wrong. Per Quinn's instructions, Jordan manages to revive her with Naloxone ("Narcan") and their countdown timers stop. Some time later, while visiting her and Jordan's mother's grave, Quinn receives word of Sullivan's arrest after more nurses have come forward to accuse him. Finally satisfied, she suddenly discovers an app called Countdown 2.0 has downloaded itself onto her phone.
In a mid-credits scene, Derek is on a Tinder date when his Countdown app causes the lights in the restaurant to go out and he is attacked by Ozhin.