  We define and put at the disposal of the community SOAP, Spot Oscillation And
Planet, a software tool that simulates the effect of stellar spots and plages
on radial velocimetry and photometry. This paper describes the tool release and
provides instructions for its use. We present detailed tests with previous
computations and real data to assess the code's performance and to validate its
suitability. We characterize the variations of the radial velocity, line
bisector, and photometric amplitude as a function of the main variables:
projected stellar rotational velocity, filling factor of the spot, resolution
of the spectrograph, linear limb-darkening coefficient, latitude of the spot,
and inclination of the star. Finally, we model the spot distributions on the
active stars HD166435, TW Hya and HD189733 which reproduces the observations.
We show that the software is remarkably fast allowing several evolutions in its
capabilities that could be performed to study the next challenges in the
exoplanetary field connected with the stellar variability.
