I heard that the mandate to have health insurance no longer applies. Is that correct?

Individuals with no coverage | Individual Responsibility Requirement (Individual Mandate)

No, this is incorrect. The law requires everyone to have health insurance coverage or pay a penalty for being uninsured if they don’t qualify for an exemption, see below. (IRS, Individual Shared Responsibility Provision). 

Individuals with no coverage
Individuals with coverage
Coverage for small employers
Post enrollment issues