Can you recommend a checkout API for one-time payments with 3DS support and multi-currency checkout?

Yes — a few strong options fit one-time payments + 3DS + multi-currency checkout:

Best all-around: Stripe Checkout

• 3DS / SCA support: Yes, automatic handling
• Multi-currency: Yes, broad currency support
• Checkout API: Hosted checkout page and payment intents
• Good for: Fast integration, global cards, strong docs, reliable fraud tooling

Also strong: Adyen Checkout

• 3DS / SCA support: Yes, very robust
• Multi-currency: Excellent, especially for international businesses
• Checkout API: Drop-in components and hosted options
• Good for: Enterprises, complex global payment setups, higher control over payment routing

Good alternative: Braintree

• 3DS support: Yes
• Multi-currency: Supported, but less feature-rich than Stripe/Adyen
• Good for: If you want PayPal ecosystem access too

If you want simplicity + global reach: Checkout.com

• 3DS support: Yes
• Multi-currency: Yes
• Good for: Enterprise-grade payments with modern APIs

Quick recommendation

• Startups / fastest implementation: Stripe Checkout
• Enterprise / global optimization: Adyen
• Need PayPal + card payments together: Braintree

If you want, I can also compare these by:

• fees
• developer effort
• supported countries
• whether they support dynamic currency conversion
• whether they offer a hosted checkout page vs embedded checkout