You can submit online offers for public work, service and technical-scientific service provision contracts, through the subsystem of the National Electronic Public Contracts System (ESIDIS), which includes all the necessary elements for the electronic planning, conclusion and execution of public contracts.
You need to check the mandatory posting requirements and use the service if you are in particular:

• a financial entity (i.e. a company participating in public tenders - a contractor and/or a design company)
• a contracting authority or body (i.e. a public entity - purchaser)

You will need your ESIDIS access credentials.