Can I accept online payments in India without a website?

Often yes. Razorpay's sign-up asks for website or app links and social-media links, and both can be added later. Stripe also accepts a social profile if you give its exact URL.

• Razorpay: sign-up asks for website or app links and social-media links. Both can be added later.
• Stripe: it accepts a social-media profile or app if you give the full URL of the specific profile.
• Still useful: an ordering link is the easiest thing to show a gateway and to give customers.
• Check: each gateway can ask for documents, so read its sign-up page before you start.