  This article presents an on-line tool (rttools.irap.omp.eu) and its
accompanying software ressources for the numerical solution of basic radiation
transfer out of local thermodynamic equilibrium (LTE). State-of-the-art
stationary iterative methods such as Accelerated $\Lambda$-Iteration and
Gauss-Seidel schemes, using a short characteristics-based formal solver are
used. We also comment on typical numerical experiments associated to the basic
non-LTE radiation problem. These ressources are intended for the largest use
and benefit, in support to more classical radiation transfer lectures usually
given at the Master level.
