Income taxes - Pre-tax Income (Loss) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Income components
United States	$ (847,719)	$ (1,818,919)
Outside United States	(270,768)	263,832
Loss before income taxes	$ (1,118,487)	$ (1,555,087)