Khalti vs eSewa for SaaS billing: integration, coverage and verification

You will end up integrating both. The useful question is how they differ in the places that bite: coverage, flow and verification.

Coverage

eSewa is a wallet: the customer pays from their eSewa balance or a linked bank. Khalti is a wallet and an aggregator: its KPG-2 checkout can open Khalti wallet, e-banking or mobile banking at a partner bank, connectIPS or SCT. Khalti exposes the live bank list at `/api/v5/bank/` (e-banking and mobile-checkout variants), which is why a checkout can say “pick your bank” and send the customer straight to Nabil or NIC Asia.

Flow

Khalti KPG-2 is server-initiated: POST `/api/v2/epayment/initiate/` with amount, order and return URL; you get a `pidx` and a `payment_url`; after the customer returns you call `/api/v2/epayment/lookup/` with the pidx. eSewa ePay v2 is a signed form post: you compute an HMAC-SHA256 over `total_amount,transaction_uuid,product_code`, redirect to the form endpoint, and eSewa redirects back with a base64 payload whose signature you must recompute and compare.

Verification is where projects go wrong

Neither return URL is proof of payment. For Khalti, treat `lookup` as the source of truth. For eSewa, verify the response signature and call the status-check endpoint if the callback is late or the amount formatting differs — a known gotcha is that eSewa serialises `1000.0` as a JSON number, so re-encoding it before hashing yields a different HMAC. Tola Pay verifies both server-side before an invoice is marked paid; your code never sees a gateway.

Fees and settlement

Both charge a per-transaction service fee set in the merchant agreement (Khalti also notes a one-time API charge and free transfers from the merchant dashboard to your bank). Neither publishes per-merchant rates; get them in writing from your account manager and model them per rail.

Which to lead with

Show both and let the customer decide. In practice Khalti wins for bank-account payers (because of the bank channels) and eSewa for wallet-first consumers. A hosted checkout that renders both — plus cards for foreign buyers and bank transfer for B2B — removes the choice from your roadmap.