This deliverable describes the algorithms underlying the data apps defined in D1.1 and whose results are reported in D3.1. While D3.1 answers the question of what the data apps produced, this deliverable addresses how those results were obtained, documenting methodological approaches, design choices, and algorithmic dependencies among the apps. Only the apps chosen for development are shown. The choice of developed apps is based on their feasibility within the project’s timeframe. Transparent algorithm documentation is relevant not only to DSOs seeking to operationalise these tools but also to researchers, electricians, and engineers who may wish to reproduce or adapt the methods in their own contexts. The descriptions are kept at a high methodological level; code-level implementation details are available in the open-source repository on GitHub. The presented apps have been categorised into three main groups, the first group comprising data apps that are particularly for data preparation and topology refinement, thereby setting the stage for their usability in other data apps. These apps include the data extractor - for time series data loading and topology refinement, SM classifier for characterisation and classification of smart meters, SM phase mapper for refining per-phase topology information and mapping SMs based on their voltage measurements, and data corrector serving as a data updating patch, particularly for cleaning SM profiles, phase correction, and topology cleaner. The second category contains data apps for phase imbalance analytics. Hence, the phase imbalance profiler and phase imbalance analyser have been presented. The last category covers apps that help identify electrification loads and the phases they are connected to. In this case, the focus was on identifying electrical heating, electric vehicles, and photovoltaic panels. For the group of electrification loads, a data app for Phase connector assistance is added that was not in D3.1, which is used as an endpoint for a service described in D4.1.