Attribution

Basemap

• © OpenStreetMap contributors — under the Open Database License (ODbL).
• © Protomaps — basemap tiles derived from OpenStreetMap.
• MapLibre GL JS — BSD-3 licensed map renderer.

Geometry

• Natural Earth — country boundaries (1:50m admin-0), public domain.

Tax & treaty data sources

• OECD Corporate Tax Statistics — SDMX API, free with attribution.
• OECD Tax Database — personal income tax rates, free with attribution.
• Tax Foundation ITCI — comprehensive OECD country data.
• Tax Foundation — worldwide corporate tax rates.
• PwC Worldwide Tax Summaries — global tax rate reference.

See methodology for full sourcing details and refresh cadence.