Abstract We study the gravitational waves (GWs) spectrum produced during the electroweak phase transition in a scale-invariant extension of the Standard Model (SM). enlarged by a dark $$ U(1)_{D} $$ U(1)D gauge symmetry. This symmetry incorporates a vector dark matter (DM) candidate and a scalar field (scalon). Because of scale invariance. https://threadheaders.shop/product-category/t-shirt/