Friends of Jenkins's refuse to disclose names, insisting that information is "confidential" because of the nature of the case.
Siôn Jenkins, 41, was jailed for life in July 1998 at Lewes Crown Court, East Sussex.
It is unclear exactly who is running the website, which was first registered in April 1999.
Friends of Jenkins's refuse to disclose names, insisting that information is "confidential" because of the nature of the case.
Although Jenkins has extremely limited access to the web while serving his sentence in Wakefield prison, he does have an active role in the website's content, regularly contributing information.
Jenkins was convicted of the murder of Billie-Jo, 13, who was battered to death with a tent peg at their family home in Hastings, East Sussex, in February 1997.
Throughout the trial, he protested his innocence, and his supporters hope the internet will raise the profile of his appeal.
"The website is run on a confidential basis," said the Reverend Stuart Bell of St Michael's Church in Aberystwyth where Jenkins worshipped while on bail awaiting trial.
"Siôn does have an input, through friends or whoever. Information and letters from him are published on the website."
The Rev Bell, who visits Jenkins monthly and continues to protest his friend's innocence, added: "I don't know exact figures, but I do know there has been a lot of interest in the site.
"In the last mailing I received from the Justice For Siôn Jenkins Group, details were given of letters and responses they had received from those who had seen the site."
The website alleges Jenkins's case - which is to be taken to the European Courts of Human Rights - was a miscarriage of justice.
It highlights a number of points which his supporters claim prove his innocence.
Jenkins was convicted of the murder after around 150 microscopic bloodspots were found on his clothes.
The website says: "With the support of all those prepared to challenge the injustice he has experienced, and in the hope of liberty, he will steadfastly continue to maintain his innocence."
In January, three judges rejected an application by Jenkins - who last year lost his appeal against conviction - to take his case to the House of Lords.
His appeal hinged on fresh evidence of tests which were said to show that the bloodspots could have come from Billie-Jo's breath as he stood over her.
Meanwhile, Billie-Jo's natural father Bill Jenkins - no relation to his daughter's killer - has petitioned Prime Minister Tony Blair "for life to mean life".
"Child murderers are getting out early all the time. Time is not a great healer. People like me are the forgotton victims and we want proper justice for our children," he said.