As millions of Israelis paused in reflection on Monday at the sound of the siren marking Holocaust Remembrance Day, the Internet here was buzzing. The first online database of more than half a million pieces of property lost by Holocaust victims, many in Eastern Europe, had just been uploaded as a first step toward restitution.

After years of quiet diplomacy that accomplished little, organizers of the new project, financed by the Israeli government, said the idea was to harness technology in the struggle for restitution and to make as much noise as possible.

“This is an activist approach,” said Bobby Brown, executive director of the Holocaust Era Asset Restitution Taskforce, known by its acronym, Project Heart. “We believe there are no secrets anymore about the Holocaust.”

Pointing to the success of public drives in the past, like the campaign for Soviet Jewry and the settlement of claims of Holocaust victims by Swiss banks, Mr. Brown said the issue of property restitution had to be out there on Twitter and Facebook, although negotiations with countries where properties were located “do not have to be made public right away.”