Antibodies are indispensable in biological research and medical diagnostics. However, their production is time-consuming, expensive, and requires the use of many animals. Scientists at the Max Planck Institute for Biophysical Chemistry in Göttingen, Germany, have now developed so-called secondary nanobodies that can replace the most-used antibodies and may drastically reduce the number of animals in antibody production. This is possible because the secondary nanobodies can be produced in large scale by bacteria. Moreover, the secondary nanobodies outperform their traditional antibody counterparts in key cell-biological applications.