The interpretation of data derived from metagenomic approaches requires computational pipelines and IT infrastructures that improve over time and are strongly linked to the availability of pre-existing data stored in online databases (e.g. National Center for Biotechnology Information). We developed ExTaxsI, a tool for large scale analysis and visualization of biological and taxonomic data that can interact with web databases. ExTaxsI is based on Python 3 programming language and has several functions organized in modules that make it a flexible tool. It can be interfaced with NCBI Database to create customized local databases that can be integrated with the main algorithms involved in taxonomic assignment (BLAST, VSEARCH). Moreover, it is possible to analyze and create files with simple queries, producing taxonomic lists, multi-FASTA or interactive and “easy to use” geographic maps with the coordinates of the records.