How to set up a merchant payment integration (Khalti / eSewa Pay) for a Shopify-like store?

Short answer: Open a merchant account, get the API keys, integrate the SDK, run a sandbox test, submit for production approval. Plan two weeks for the back-and-forth.

Practical steps.

1. Merchant onboarding — company registration, PAN, bank account, signed merchant agreement.
2. API keys — public (browser-safe) and secret (server-only).
3. SDK integration — Khalti and eSewa both publish web/mobile SDKs.
4. Sandbox test — happy path, failure path, refund.
5. Production review — KYC, settlement bank, payout schedule.

The exception most miss. Settlement timing differs by wallet. eSewa typically T+1; Khalti varies by plan. Communicate to your finance team before the first sale.

Which integration tripped you up? Tell the next developer.