Share-based compensation - Options - Fair Value Assumptions (Details) - Employee Stock Option - $ / shares	1 Months Ended
	Apr. 30, 2024	Mar. 31, 2024	Apr. 30, 2023	Mar. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate (%)	4.54%	4.21%	3.50%	3.65%
Expected volatility range (%)	55.32%	55.11%	63.39%	63.36%
Fair market value per ordinary share as at grant dates (in dollars per share)	$ 1.32	$ 1.50	$ 1.74	$ 2.08