Motivation: Bioinformatics software often lacks graphical user interfaces (GUIs), which can limit its adoption by non-technical members of the scientific community. Web interfaces are a common alternative for building cross-platform GUIs, but their potential is underutilized: web interfaces for command-line tools rarely take advantage of the level of interactivity expected of modern web applications and are rarely usable offline. Results: Here we present Pline: a lightweight framework that uses program descriptions and web standards to generate dynamic GUIs for command-line programs. With Pline, cross-platform graphical interfaces are easy to create and maintain, fostering user-friendly software in science. Availability and Implementation: Pline is cross-platform, open-source software. Documen-tation, example plugins and source code is freely available from http://wasabiapp.org/pline