Sara Payne said former editor Rebekah Brooks and retired managing editor Stuart Kuttner had lent their support after her eight-year-old daughter was abducted and murdered in 2000.
She told jurors at the Old Bailey that Brooks was at the forefront of the long-running Sarah's Law campaign to protect children from predatory paedophiles.
Mrs Payne said: "It's easy to forget in these dark times the NotW has often been a force for good and it has something to do with the people who worked on it."
She added: "I do not pretend they are perfect or always got things right," before describing Kuttner as a gentleman and Brooks as "really sweet".
She told how they worked as a team on Sarah's Law, sharing their research.
She said: "I did not sleep. I could call at two o'clock in the morning and she would pick up the phone."
Mrs Payne, who was called by Kuttner's legal team as a character witness, said he helped steer her through the newspaper industry and meeting politicians as part of the campaign.
Brooks, 45, Kuttner, 74, and all of their co-defendants deny the charges against them.
When Kuttner returned to the witness box to continue his evidence, he denied holding back a possible lead in the disappearance of murdered schoolgirl Milly Dowler.
Private investigator Glenn Mulcaire hacked into Milly's phone for the NotW after she went missing in 2002, the court heard.
Kuttner alerted police to a voicemail message suggesting Milly may be alive, said prosecutor Andrew Edis, QC, but only after journalists had been dispatched in an attempt to track her down.
Cross-examining, Mr Edis asked Kuttner: "How did you think the NotW had come by the message?"
Kuttner said: "I have no recollection."
The trial continues.