A needle free injection device suitable for delivering a therapeutic substance into the intradermal space of a patient. The needle free injection device includes a main spring which can be compressed using one or more handles attached to the device to place the needle free injection device into an armed configuration. Device embodiments may optionally include an injector tube and associated apparatus which may be moved relative to other device structures when the injector is pressed against the skin of a patient with sufficient force. The disclosed operational switches and release mechanisms cooperate to prevent injection unless the device is properly positioned for an injection. Needle free injection systems and methods of operating a needle free injection device are also disclosed.
