Numo is a free, open-source Android app that lets merchants accept Bitcoin payments with a simple "tap" using NFC (Near Field Communication) technology, similar to Apple Pay or Google Pay .
📝 Before You Start: The Basics
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What you need: An Android smartphone with NFC (Near Field Communication) capabilities. The app does not require any additional hardware like a separate payment terminal .
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What it uses: The app is built on the Cashu protocol, an open-source ecash system for Bitcoin. It also supports standard Lightning Network payments, making it compatible with many different Bitcoin wallets .
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Cost: Numo charges zero platform fees. Merchants keep 100% of their sales .
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Availability: The app is currently available as a direct download (APK) from the official website,
numopay.org. A release on the Google Play Store is expected soon .
🧭 Step-by-Step Guide for Merchants
Here is how to get started and use Numo to accept Bitcoin in your store.
Step 1: Install and Set Up Numo
First, download the Numo app from numopay.org and install it on your NFC-enabled Android device. Open the app to begin .
Step 2: Configure Your Receiving Preferences (Important!)
Before you start making sales, it's wise to set up how you want to receive your Bitcoin. Numo holds incoming payments as "ecash" on a mint (a third-party server) . To reduce risk, the app offers a key feature called Auto-Sweep.
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Find the "Auto-Sweep" setting: Look for this option in the app's configuration menu.
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Set a threshold: You can define an amount (e.g., 100,000 sats). Once your balance reaches this limit, the app will automatically send the funds to your personal, external Lightning wallet address. This helps you maintain control over your Bitcoin .
Step 3: Receive a Payment from a Customer
When a customer is ready to pay, follow these simple steps:
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Open the App: Launch the Numo app on your phone. The app should be ready to receive payments.
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Customer Taps: The customer holds their NFC-enabled Bitcoin wallet (like another Cashu wallet) near your device .
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Payment Processes: The payment token is transferred instantly via NFC. The transaction completes in just a few seconds, providing a smooth experience .
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Confirmation: You and your customer will see a confirmation of the payment on your screens.
Step 4: Accepting Payments from Any Lightning Wallet
Even if your customer doesn't have a Cashu wallet, they can still pay you.
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The Numo app can also generate a standard Lightning invoice.
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The customer can scan the QR code or copy the invoice from your device and pay it with any Lightning-compatible wallet, like Wallet of Satoshi or Breez .
✨ Key Features to Explore
Numo includes several features designed for small businesses:
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Offline Payments: You can accept payments even if your internet connection is down. The app supports offline transactions, which is a major advantage over traditional card terminals .
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Inventory Management: The app has built-in tools to help you track your products .
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Tipping: You can easily accept tips from customers .
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Payment History: You can review your past transactions directly in the app .
⚠️ A Note on Cashu Mints
Since Numo uses the Cashu protocol, it's helpful to understand the role of a mint. A mint is a server that holds the Bitcoin collateral for the ecash tokens .
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For small, everyday transactions, the risk is low, but it's important to know that your balance on the app is held by a third party until you withdraw it (or until the auto-sweep feature does it for you) .
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Using the Auto-Sweep function is a best practice to regularly move your funds to a wallet where you control the private keys