Lewisham Council is asking its own staff to help find £95m in savings with the help of new 'crowdsourcing' software.
The local authority needs to make the cuts over the next four years and is turning to its own employees for "innovative" and "game-changing" ideas.
Under the scheme, staff can submit their proposals using a new software platform designed by company Wazoku.
Council chief exec Barry Quirk said: "To say that finding such cost savings will be a major challenge is an understatement and to achieve such demanding financial targets we will need innovative and game-changing ideas from all our staff.
"But in reducing costs we also have the opportunity to be more productive in how we work and build a better borough for the next decade. Innovative ideas can come from anywhere within an organisation and it is for precisely this reason that we are using this tool.
"We will involve our staff in the change process and give them some ownership of those changes too."