The plethora of available Web design guidelines induces a credibility problem for designers: since most guidelines come from sources having various confidences, to what extent does applying these guidelines lead to a more usable web site that will be better accepted by users? A corpus of tested web design guidelines is therefore expected to answer that question. To reach such a corpus, five steps were performed: firstly, guidelines sources were categorized according to a source model; secondly, the most representative and interesting guidelines sources were selected according to certain criteria; thirdly, the selected guidelines were then categorized according to a general purpose model and subsequently gathered into an initial corpus; fourthly, particular guidelines subject to a user survey were identified; fifthly, these guidelines have been tested to see if users perceive any benefit in applying them. A first corpus of such guidelines was consequently composed into three parts: text-only sites, graphical sites, and framed sites. The contents of this corpus were used to develop an on-line version by a bootstrapping approach