The Scottish parliament is looking for a new partner to continue running its e-procurement system.
The eProcurement Scotland service has grown to include around 100 organisations over the past three years, ordering £8.6bn worth of services for the public sector.
The service says growth of between 30% and 35% is "expected but not guaranteed" over the next 24 months.
It wants a strategic partner to provide business and technology support for "business continuity and incremental improvements to the service".
The partner will be expected to work on projects including interoperability of software, implementation of new technology and creating a single-point-of-contact helpdesk.
The work will take around 48 months from the date the contract is awarded, but the tender document gives no indication of the value of the contract. The full scope of the work will be defined at a later stage of the tender process, the organisation said.