Traditional methods for the generation of nucleotide variant libraries can create premature stop codons and incorporate redundant codons, which leads to poor control and uneven distribution of diversity. Twist Bioscience’s silicon-based DNA synthesis platform, on the other hand, enables precise synthesis of variants to allow unprecedented, efficient, and comprehensive interrogation of the single variant space. Precision synthesis at the nucleotide and codon levels enables inclusion of desirable variants and exclusion of undesirable variants. New data demonstrate the ability of Twist Bioscience’s synthesis technology to construct nucleotide variant libraries and barcoded libraries for the in-depth examination of DNA or amino acid sequence space.