In general, typesetting experimentation is not a very practical thing to do. WYSIWYG typesetting systems are very reactive but do not offer highly configurable algorithms, and TeX, with its separate development / compilation / visualization phases, is not as interactive as its WYSIWYG competitors. Being able to experiment with typesetting algorithms interactively and in real-time is nevertheless desirable, for instance for demonstration purposes, or for rapid prototyping and debugging of new ideas. We present ETAP (Experimental Typesetting Algorithms Platform), a tool written to ease typesetting experimentation and demonstration. ETAP currently provides several paragraph justification algorithms, all with many configuration options such as kerning, ligatures, flexible spaces, sloppiness, hyphenation, etc. The resulting paragraph is displayed with many visual hints as well, such as paragraph, character, and line boxes, baselines, over/underfullness hints, hyphenation clues, etc. All these parameters, along with the desired paragraph width, are adjustable interactively through a GUI, and the resulting paragraph is displayed and updated in real-time. But ETAP can also be used without, or in conjunction with the GUI, as a scriptable application. In particular, it is able to generate all sorts of statistical reports or charts on the behavior of the various algorithms, for instance, the number of over/underfull boxes per paragraph width, the average compression or stretch ratio per line, whatever else you want. This allows you to quickly demonstrate or evaluate the comparative behavior or merits of the provided algorithms, or whichever you may want to add to the pool.