Accept USDC subscriptions in minutes

Quickstart

From zero to first payment in four steps:

Create a product

From your merchant dashboard, click Add product. You'll configure:

Share your pay link

Every product generates a unique pay link:

https://authonce.io/pay/{merchant-slug}/{product-slug}

From your dashboard you can:

• Copy the URL directly
• Download a QR code to use in print, email, or presentation slides
• Share via WhatsApp, email, or any messaging app

The pay page is fully responsive and works on any device. Subscribers choose their payment method on arrival — no friction, no account required.

Payment methods

AuthOnce is fully non-custodial. Every payment method moves USDC, EURC, or USDT directly from the subscriber's own wallet to yours — AuthOnce never processes a card, never touches fiat, and never holds a key to either side's funds.

USDC / EURC — one signature, gasless

The subscriber connects a wallet and signs a single EIP-2612 permit. No gas required. From that point, AuthOnce's keeper bot pulls the subscription amount on each billing date directly to your wallet. The subscriber never needs to sign again.

USDT — two-step approval

USDT doesn't support EIP-2612 permits. The subscriber approves the vault on-chain first (one gas transaction), then confirms the subscription. Slightly more friction up front than USDC/EURC, but the same non-custodial, pull-based billing from then on.

Subscribers without a stablecoin wallet yet

AuthOnce doesn't process cards and doesn't touch fiat at any point. A subscriber who doesn't already hold USDC, EURC, or USDT gets it through an onramp partner (Circle or Coinbase Onramp), which delivers stablecoin straight to their own wallet — AuthOnce is never in that path. This onramp integration is not yet live; until it is, subscribers need a stablecoin wallet before they can subscribe.

Grace period & dunning

When a payment fails — either because the subscriber's wallet has insufficient balance or their approval expired — AuthOnce does not immediately cancel the subscription. Instead, it enters a grace period.

During the grace period:

• The keeper retries the payment once every 24 hours
• The subscriber receives an email notification immediately, and a reminder every 48 hours
• You receive a notification that the payment failed and the grace period end date
• The subscription status shows as Grace in your dashboard

If the subscriber tops up their wallet (or re-approves), the next daily retry will succeed and billing continues normally. If the grace period ends with no successful payment, the subscription expires.

Fees

AuthOnce charges a single flat fee, hardcoded in the smart contract:

Webhooks

Webhooks let your backend react in real time to subscription events. AuthOnce sends a signed HTTPS POST to your endpoint within seconds of each event.

Configure your webhook endpoint

From Dashboard → Settings → Webhooks, enter your endpoint URL. AuthOnce will sign every request with HMAC-SHA256 using your webhook secret.

Every webhook payload follows the same structure:

{
  "event":     "payment.success",
  "timestamp": 1750000000,
  "data": {
    "subscription_id": "42",
    "merchant_address": "0xbb6d...",
    "vault_address":    "0xd889...",
    "amount_usdc":      "10.00",
    "merchant_received_usdc": "9.95",
    "tx_hash":        "0xecb0...",
    "status":         "active"
  }
}

Webhook events

Signature verification

Every webhook includes an X-AuthOnce-Signature header. Always verify it before processing the event — it protects you from spoofed requests.

// Node.js example
const crypto = require("crypto");

function verifyWebhook(rawBody, signature, secret) {
  const expected = "sha256=" + crypto
    .createHmac("sha256", secret)
    .update(rawBody)
    .digest("hex");
  return crypto.timingSafeEqual(
    Buffer.from(expected),
    Buffer.from(signature)
  );
}

// In your Express route:
app.post("/webhook/authonce", (req, res) => {
  const sig = req.headers["x-authonce-signature"];
  if (!verifyWebhook(req.rawBody, sig, process.env.AUTHONCE_WEBHOOK_SECRET)) {
    return res.status(401).send("Unauthorized");
  }
  // Safe to process
  const { event, data } = req.body;
  // ...
  res.status(200).send("OK");
});

Dashboard

Your merchant dashboard at authonce.io gives you:

• Subscribers — list of all active, grace, cancelled, and expired subscribers with wallet addresses and payment history
• Payments — full payment history with transaction hashes, amounts, and Basescan links
• Analytics — MRR, GTV, ARPU, churn rate, new vs churned subscribers over time
• Webhooks — delivery log, retry status, response codes
• Products — manage all your subscription products

Cancellations

If you need to stop billing a subscriber, contact them directly and ask them to cancel from their subscriber portal at authonce.io/my-subscriptions. Alternatively, you can pause your product from the dashboard — no new payments will be attempted while paused.

Tax exports

From Dashboard → Payments → Export, you can download:

• CSV — all payments with date, subscriber, amount in USDC and EUR equivalent, transaction hash
• XLSX — same data as a spreadsheet, with a separate guide tab explaining the columns for your accountant

Pricing tiers