Lyra McKee wanted to expose the truth, a close friend said.
She was an incredible investigative journalist and a defender of press freedom, a GoFundme fundraiser page added.
Her first book, Angels With Blue Faces, is a non-fiction investigation of the murder of Robert Bradford, a Methodist minister and Ulster Unionist politician for South Belfast who was killed by the IRA in 1981.
The 29-year-old from Belfast was hailed as a powerful advocate for LGBTI rights, civil liberties and human rights.
The fundraising page said: “Lyra was a passionate defender of press freedom and exposing the truth.
“You don’t expect journalists to be killed anywhere.
“For it to happen to a friend, in a (troubled) democracy, is just unbelievable.”
She was described as part of a new generation of Northern Irish journalists (and young people) who had moved past sectarian identities and wanted to build a more progressive, more peaceful Northern Ireland.
She worked on the grassroots campaign to reform the law of libel in Northern Ireland.
Thousands have been raised towards funeral expenses.
- Press Association