  We present the Mathematica package SpinorHelicity4D, a dedicated suite for
analytic and numeric calculations involving four-dimensional massless and
massive spinor-helicity formalism. Analytic features of the package include for
example: manipulation of contracted and uncontracted spinor quantities,
automated application of Schouten identities for expression simplification,
contractions of spinor products into chains, re-expression of chains in terms
of Dirac traces and evaluation of such traces, derivatives of arbitrary
functions of spinor quantities. Numeric features of the package include among
others: generation of arbitrary $n$-point numerical complex kinematics,
allowing for both massless and massive external states, fully numeric or
parametric kinematics, and numeric generation on either $\mathbb{R}$ or
$\mathbb{Q}$, the latter providing output immediately suitable for finite field
applications. Furthermore, the package features user-friendly, intuitive but
also highly customizable input options, thus providing an approachable tool for
the casual user while still supporting more advanced applications for more
adept and frequent users. All of the output is returned in the standard bracket
notation, making it easily interpretable, but at the same it retains all of the
analytic properties of the objects, allowing for copy-pasted and manipulated
output to be provided as new input. This makes it ideal for front-end
applications on a Mathematica notebook, while still allowing for deployment on
a cloud server for more heavy calculations.
