Causal is a browser-based modeling tool, to replace spreadsheets. What's wrong with spreadsheets? Spreadsheets can't handle uncertainty. Most quantities in a model aren't precisely known, but spreadsheet cells hold fixed values. Without uncertainty, you can't know how confident to be in your results. Causal’s models are probabilistic, letting you understand the uncertainty of your results. Spreadsheet models are opaque. Spreadsheet cell references are invisible — the only way to understand your model’s structure is by tracing through each cell and its references, one by one. Causal’s visual diagrams immediately show how your model works. Spreadsheet cells are all the same. Your model has different parts — inputs, constants, functions, outputs. A spreadsheet just has cells. This makes it difficult to manage, and leads to conceptual errors. Causal's abstractions are designed just for modeling.