Biocatalysis is an environmentally friendly, cost-efficient alternative to chemocatalytic synthesis. Yet improvements in specificity and efficiency are needed and have to be generated quickly to meet the fast pace of product development in industry. This ambition is met by droplet microfluidics, a powerful tool to scan vast libraries at kHz speed with >107/day throughput. Instead of μl robotic liquid handling systems, pl water-in-oil emulsion droplets are generated in polydimethylsiloxane (PDMS) chips, replacing the use of plasticware.