Hosted checkout

Every payment has a hosted checkout page at https://pay.codeappear.com/pay/{reference} (returned as checkout_url when you create the payment). The page walks your customer through the payment in Bangla and English:

1. The customer picks a provider (bKash / Nagad / Rocket / Upay) from your active MFS accounts.
2. They see your number, the exact amount due (which may include a small gateway charge), and step-by-step Send Money instructions.
3. After sending the money, they enter the TrxID from their confirmation SMS and the number they sent from.
4. The page polls while Fastaar matches the SMS forwarded by your paired phone — usually under a minute — then shows the result.

amount vs amount_due

amount is the price you set. amount_due is what the customer must actually send — it equals amount plus any cash-out charge configured on the selected payment method (a fixed or percentage fee to cover the provider's cash-out cost). The checkout page always shows amount_due.

Integration tips

• Redirect to checkout_url right after creating the payment; the link is single-use and expires.
• Pass success_url and cancel_url to send the customer back to your site when they finish or cancel. Fastaar appends payment_id and invoice_number to the URL.
• invoice_number is required — your order reference, echoed back in the API response, webhooks, and the success redirect. Use metadata for any extra key/values.
• invoice_number is idempotent: retrying with the same value while the previous payment is still active is rejected with 409 duplicate_invoice_number instead of creating a duplicate. Look the existing payment up with GET https://pay.codeappear.com/api/v1/payments?invoice_number=… rather than retrying blindly.
• Add per-account instructions (e.g. "Use reference: shop") under MFS Accounts — they appear on the checkout page.
• The success redirect is for UX only — confirm orders from the payment.completed webhook, which is the source of truth.

Checkout domain

By default checkout_url, payment link, and invoice URLs are served on Fastaar's own domain. Under Developer → Domains in the merchant panel you can point a subdomain you own — e.g. pay.yourshop.com — at Fastaar, so customers pay on your own domain instead. How many domains you can register depends on your plan's Domain Limit.

1. Pick a subdomain you own for checkout, e.g. pay.yourshop.com — don't use your root domain.
2. In your DNS settings, add a CNAME record pointing that subdomain at the target host shown on the Domains page in the merchant panel.
3. Wait for DNS to propagate — this can take a few minutes up to a few hours depending on your registrar.
4. Add the domain in the merchant panel, then click Verify. Fastaar checks the CNAME automatically and marks the domain verified once it resolves correctly.

Once verified, checkout_url for new payments, payment links, and invoices under that merchant automatically use the domain. Existing/already-generated URLs are not rewritten. TLS for the domain is handled at the infrastructure level (reverse proxy) — this only covers domain ownership verification and URL generation.