In the world of commercial construction, BuildingConnected (now part of Autodesk Construction Cloud) is a heavyweight. It’s the go-to platform for general contractors (GCs) to send out bid packages, and for subcontractors to find work.
However, to actually submit a bid through that board, you typically need the GC to invite you or you need a higher-tier account. If the free tier of BuildingConnected doesn't meet your needs, consider these genuinely free (or freemium) alternatives: buildingconnected free