vonpay-checkout

Python SDK for the Von Payments Checkout API. Create hosted checkout sessions, verify webhook signatures, and validate signed return redirects.

Install

pip install vonpay-checkout

Requires: Python 3.9+, httpx 0.27+

Quick start

from vonpay.checkout import VonPayCheckout, VonPayError

client = VonPayCheckout("vp_sk_test_...")

session = client.sessions.create(
    amount=1499,
    currency="USD",
    country="US",
    success_url="https://example.com/order/123/confirm",
)

print(session.checkout_url)
# https://checkout.vonpay.com/checkout?session=vp_cs_test_...

Discrete-lifecycle API

The payment_intents, refunds, tokens, and capabilities namespaces give server-side control over payment intents, alongside the existing hosted-checkout sessions flow.

# Create a payment intent (auth + capture)
intent = client.payment_intents.create(
    amount=1499,
    currency="usd",
    capture_method="automatic",
    metadata={"order_id": "ord_42"},
    idempotency_key="ord_42-charge-1",
)
print(intent.id, intent.status)  # "vpi_live_…", "succeeded"

# Auth-only + later capture (fulfillment-on-ship)
auth = client.payment_intents.create(amount=1499, currency="usd", capture_method="manual")
client.payment_intents.capture(auth.id, amount_to_capture=1499)

# Refund a captured intent (partial or full)
refund = client.refunds.create(payment_intent=intent.id, amount=500)

# Create a reusable token for save-card / MIT flows
token = client.tokens.create(buyer_id="buyer_42", setup_for_future_use="off_session")

# Read the merchant's processor capability matrix before invoking optional ops
caps = client.capabilities.get()
if caps.supported_operations.partial_refund:
    # partial refunds supported — safe to offer partial-refund UI
    ...

Features

• Typed session / webhook / error objects — full CheckoutSession, SessionStatus, WebhookEvent, VonPayError types.
• Webhook verification — webhooks.construct_event(raw_body, signature_header, signing_secret) parses the x-vonpay-signature: t=<unix>,v1=<hex> header, verifies HMAC-SHA256 over f"{t}.{raw_body}" keyed by your per-endpoint signing secret (whsec_…), and enforces the freshness window (≤5 min old / ≤30 sec future). Accepts multiple v1= entries for zero-downtime secret rotation.
• Return confirmation — client.sessions.confirm_return(params, session_secret) verifies the signature and confirms server-side that the payment succeeded, returning ReturnOutcome(paid, signature_valid, status, reason). Use this, and branch on paid. ⚠️ verify_return_signature() is the low-level primitive: it proves the message is AUTHENTIC, and a declined payment is signed just as validly, so a true from it is not proof of payment. ⚠️ reason == "still_pending" means the charge is in flight (the ordinary 3-D Secure case) — show a neutral "confirming your payment", never a failure. ⚠️ paid: true still does not mean safe to fulfil: record which session IDs you have already fulfilled, and prefer fulfilling from the charge.succeeded webhook. ⚠️ Not session.succeeded — that event is emitted internally but is not subscribable: it is absent from the merchant subscription catalog, which accepts an unknown event key, stores nothing and returns success. An endpoint subscribed to it receives nothing, forever, with no error raised at any layer. charge.succeeded is the fulfilment event.
• Auto-retry — exponential backoff on 429 / 5xx with Retry-After header support.
• Request ID tracing — every response includes X-Request-Id for support tickets.

Documentation

• Python SDK reference
• API reference
• Quickstart

License

MIT