Java语言写成的绘制RNA二级结构的软件，需要安装JAVA虚拟机。

loopDloop is a tool for drawing RNA secondary structures in molecular biology.

loopDloop will read files that include biosequence data with base pairing information. It will display graphical views of the sequence's secondary molecular structure. Various options allow one to modify, adorn and edit the structure. Standard application functions to save, print, edit and manage preferences are included. This program will not estimate nor produce the base pairings needed for secondary structure. For that, other software such as RNAFOLD, MulFOLD, and multiple sequence alignment editors may be used.