This paper presents the modelization and visualization tools for para-texts studies. Using as an example corpora the commentaries from Juste Lipse to the Annales from Tacite, we defend the benefits of ad hoc solutions, specific to the very project scientific objectives, combined with the respect of standards, useful for documentation and data and tool re-use: we use the term Digital Laboratory (Laboratoire Numérique) in contrast to, for example, Digital Edition (Édition Numérique). Our approach is based on the following principles: start with questioning and defining the nature of the object of study; serve the scientific objective as first goal and main criteria; solutions must allow reuse of data, tools and methodology.