Liverpool led the tributes to Jota, saying the club was “devastated” by such an “unimaginable loss”.
He scored 65 goals in 182 appearances for Liverpool, helping them win the FA Cup and League Cup in 2022 and the Premier League title last season.
The club put out further statements later on Thursday, with boss Slot paying tribute to a player who had become “a loved one to all” at the club.
The Dutchman added: “Someone who made others feel good about themselves just by being with them. A person who cared deeply for his family.”
Slot said he last spoke to Jota to congratulate him on Portugal winning the Nations League and wish him luck for his wedding.
“In many ways, it was a dream summer for Diogo and his family, which makes it all the more heartbreaking that it should end like this,” he added.
Slot said Liverpool and their supporters are “all with” Jota’s family and the “the same can be said of the wider family of football”.
Reds captain Virgil van Dijk said it was a “privilege” to have played alongside Jota and been his friend off the pitch.
“We will miss you beyond words and never forget you,” added the Dutchman. “Your legacy will live on, we will make sure of it.”
Left-back Andy Robertson said Jota was “the most British foreign player” he had met.
In an Instagram post, the Scotland international added: “The last time I saw him was the happiest day of his life – his wedding day. I want to remember his never-ceasing smile from that magical day. How much he was bursting with love for his wife and family.”
A statement from the club’s owners and leadership group, Billy Hogan, John Henry, Tom Werner and Mike Gordon, said they have been left “numb with grief” as they offered condolences to Jota’s family.
They added: “Beyond the player that we all knew was a wonderfully humble human being, he was sincere, intelligent, funny, tough and created connections with people everywhere he went. He had a zest for life that was utterly contagious.”
Liverpool sporting director Richard Hughes and Fenway Sports Group chief executive of football Michael Edwards said in a statement: “This is a tragedy that transcends Liverpool football club.”
They added the club will look to honour Jota with the “respect and affection” he deserves in the coming days, but for now “express a love that is filled with deep sorrow and pain” after losing someone “truly irreplaceable”.