Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the reference to our firm under the caption “Experts” and to the use of our report dated June 16, 2017, in the Registration Statement (Form S-1) and related Prospectus of Altair Engineering Inc. for the registration of shares of its common stock.

/s/ Ernst & Young LLP

Detroit, Michigan

September 29, 2017