v3.25.4
Income taxes - Summary of Income Tax Expense (Details) - CHF (SFr)
SFr in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Income tax expense SFr 0 SFr 3 SFr 10
Deferred tax assets 0 0 0
Deferred tax liabilities 0 0 0
Income tax expense reconciled to loss before tax      
Loss before income tax (70,447) (50,913) (54,223)
Tax benefit calculated at the domestic rates applicable in the respective countries (9,586) (6,925) (7,371)
(Income not subject to tax)/expenses not deductible for tax purposes 598 692 611
Effect of unused tax losses and tax offsets not recognized as deferred tax assets 8,988 6,236 6,770
Effective income tax rate expense SFr 0 SFr 3 SFr 10
Minimum      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Applicable tax rate 13.60% 13.60% 13.60%
Maximum      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Income tax expense SFr 100 SFr 100 SFr 100
Applicable tax rate 34.00% 33.80% 33.80%
Income tax expense reconciled to loss before tax      
Effective income tax rate expense SFr 100 SFr 100 SFr 100
Weighted average      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Applicable tax rate 13.60% 13.60% 13.60%
SWITZERLAND      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Applicable tax rate 13.60% 13.60% 13.60%