Disclosed are foam compositions and processes to form closed-cell tannin-based foams. The foams comprises a continuous polymeric phase defining a plurality of cells, wherein the continuous polymeric phase comprises a tannin-based resin derived from a tannin and a monomer, wherein the monomer comprises furfural, glyoxal, acetaldehyde, 5-hydroxymethylfurfural, acrolein, levulinate esters, sugars, 2,5-furandicarboxylic acid, 2,5-furandicarboxylic aldehyde, urea, difurfural (DFF), furfuryl alcohol, glycerol, sorbitol, lignin, or mixtures thereof, and wherein the plurality of cells comprises a plurality of open-cells and a plurality of closed-cells with an open-cell content measured according to ASTM D6226-5, of less than 50%. The foam composition also comprises a discontinuous phase disposed in at least a portion of the plurality of closed-cells, the discontinuous phase comprising one or more blowing agents.