<p>Equity<?tk 1?> in public transit accessibility is increasingly recognized as a critical planning objective, yet existing evaluation tools often fall short in interpretability and operational relevance. This paper introduces a practical and reproducible toolbox designed to assess vertical equity in spatial accessibility, focusing on disparities between potentially vulnerable and non-vulnerable populations. Grounded in a Rawlsian equity perspective, the toolbox combines two accessibility indicators, public transit accessibility and urban opportunity accessibility, with three intuitive equity metrics and two graphical diagnostic tools. To demonstrate the applicability of the toolbox, we use the indicators to assess the current equity situation of spatial accessibility on the territory of the Montreal regional transport authority. The preliminary investigation reveals the existence of a specific study area experiencing significant levels of inequity in 2023. In this area, vulnerable populations experience 12–19% lower median accessibility and are disproportionately concentrated in low-accessibility areas. Classical equity indices such as Gini, Theil, and Atkinson suggest relatively fair overall distributions, but fail to capture these group-specific disparities, underscoring their limitations in vertical equity analysis. We also demonstrate how this toolbox can be used for scenario analysis by updating the results with a projection of the public transit network of 2033. The scenario shows improved accessibility and reduced inequity, with median values converging between groups and underrepresentation in high-accessibility areas diminishing. Overall, the toolbox offers a scalable, interpretable framework for diagnosing equity in transit planning, enabling planners to identify priority areas, set equity targets, and evaluate the impacts of future interventions.</p>