The key tools used in recombinant DNA technology are -

1. EnzymesRestriction Enzymes: Hind II, EcoRI, EcoRI I, Smal, EcoR V are most commonly used restriction enzymes. That cut the DNA at specific sit.
   Ligase: Responsible for the joining of cut ends.
   Protease: Degrade the proteins present along with DNA eg. Histone.
   
2. Cloning Vectors: Plasmids and bacteriophages are used as cloning vector because they have ability to replicate.
3. Competent Host: Competent host cells are able to take up foreign DNA it.