Free Sankey diagram tools: the five kinds, and which to pick

1. Text-syntax web tools

Tools such as SankeyMATIC run in the browser and draw a Sankey from lines of text in their own format, roughly "Source [amount] Target". They are free and quick for someone who learns the syntax, and good for a single diagram you build in one sitting.

Where they get in the way: the data has to be rewritten into the syntax, which is awkward when it starts life as a spreadsheet, and a typo in the format is easy to miss.

2. Code libraries

Plotly (Python and JavaScript), D3 with its Sankey module, and Google Charts all draw Sankey diagrams from code. They are free, endlessly configurable, and the right choice for a diagram that lives inside an application or refreshes from a database.

Where they get in the way: you need a developer, nodes are referenced by index, and every change to the numbers is a change to the script.

3. Business-intelligence visuals

Power BI offers Sankey diagrams through custom visuals, and Tableau users build them with calculated fields or extensions. That suits a team whose data already lives in the BI tool and whose diagram belongs on a dashboard.

Where they get in the way: setup takes time, the free tiers limit sharing, and a one-off diagram for a report is a lot of machinery.

4. Spreadsheets

Excel and Google Sheets have no built-in Sankey chart type. The workarounds (stacked area tricks, add-ins, or a script) can produce one, but they are fragile, and the result is hard to edit afterwards. Spreadsheets are excellent for holding Sankey data; they are a poor place to draw it.

5. Typed Sankey editors

A typed editor keeps the data in a sheet and draws the diagram from it, live. SankeyCharts.app is one: one row per node, where it flows and how much, or a pasted source, target, value list. There is no syntax and no code, the bands are sized and laid out automatically, and every node's inflow is checked against its outflow.

Where it gets in the way: it is not a database pipeline. A diagram that must refresh by itself every night still belongs in code or a BI tool.

How to choose

Pick by who owns the numbers and how often they change:

• A developer, and the numbers change automatically: a code library
• An analyst, and the data already lives in a BI model: a BI visual
• Anyone, one diagram, comfortable learning a format: a text-syntax tool
• Anyone, data in a spreadsheet, numbers edited by hand: a typed editor

• Sankey chart best practices: ten rules for clear diagrams (QueryChart)

Frequently asked questions