On which trading platforms is it better to place job offers on a competitive basis?

Question

Business Informatics

Good day everyone! As the head of the IT department at a large plant in the Leningrad Region, I constantly face the problem of finding contractors for work (not only in the field of IT) - video surveillance (installation of 36 cameras on the territory of the industrial complex, laying fiber optic lines on the territory of the plant, organizing an access control system, etc. .d.). I would like to clarify the following with knowledgeable people: are there trading platforms for holding a competition for such work, when, according to the terms of reference, several companies can form a commercial offer? Which ones are better?