Primer Pay

A browser extension that automatically handles x402 payments as you browse.

What is Primer Pay?

Primer Pay is a Chrome extension that detects HTTP 402 responses and handles payment automatically. When you visit a paid resource, the extension intercepts the request, signs a payment authorization, and retries — all without leaving the page.

Key features:

• Automatic interception — patches fetch and XMLHttpRequest to detect 402 responses
• Gasless payments — signs EIP-712 authorizations off-chain, no gas required
• Spend controls — per-payment limits, daily caps, confirmation thresholds
• Transaction history — track all payments by domain

Installation

Primer Pay is currently in beta. To install:

1. Download the extension from GitHub Releases
2. Open Chrome and go to chrome://extensions/
3. Enable "Developer mode" (toggle in top right)
4. Click "Load unpacked" and select the extension folder

Getting Started

After installation:

1. Create a wallet — click the extension icon and choose "Create Wallet". Set a 4-6 digit PIN.
2. Save your recovery phrase — write down the 12-word mnemonic. This is the only way to recover your wallet.
3. Fund your wallet — send USDC (on Base) to your wallet address. Click "Receive" to see your address and QR code.
4. Browse — the extension automatically handles 402 responses within your spend limits.

Dashboard

The main popup shows your balance, daily spend, and recent transactions:

The dashboard shows your USDC balance, daily spend progress, and recent transactions.

Spend Controls

Configure limits to control automatic payments:

Confirmation Modes

• Auto-pay all — never prompt, pay automatically within limits
• Confirm above threshold — prompt for payments above a set amount
• Always confirm — prompt for every payment

When confirmation is required, a modal appears:

The confirmation modal shows the amount and destination before you approve.

Supported Networks

Premium Features

Hold 100,000 PR tokens on Base to unlock:

• Additional networks — Ethereum, Arbitrum, Optimism, Polygon
• Domain allowlist — restrict payments to specific domains
• Custom RPC endpoints — use your own RPC nodes
• CSV export — export full transaction history
• Extended history — 1,000 transactions (vs 100 for free tier)

Security

• PIN protection — wallet is encrypted with your PIN
• Auto-lock — wallet locks after inactivity (configurable: 1-60 minutes)
• Rate limiting — max 10 payments per minute per domain
• Local storage — private keys never leave your device

Backup & Recovery

Your wallet can be recovered using the 12-word mnemonic phrase shown during creation. You can also export your private key from Settings > Security > Export Private Key.

Importing an Existing Wallet

If you already have a wallet, you can import it using either a recovery phrase or private key:

1. Click the extension icon and choose Import Wallet
2. Select either Recovery Phrase or Private Key tab
3. Enter your 12 or 24 word mnemonic, or paste your private key
4. Set a new PIN for this device
5. Click Import

Import an existing wallet using a recovery phrase or private key.

Receiving Funds

To add USDC to your wallet:

1. Click Receive from the dashboard
2. Copy your wallet address or scan the QR code
3. Send USDC on the Base network to this address

The receive screen shows your address and a QR code for easy funding.

Settings

Access settings by clicking Settings from the dashboard. The settings panel is organized into three sections:

The settings panel shows spend controls, premium features, and network configuration.

Domain Allowlist (Premium)

Restrict automatic payments to specific domains. When enabled, payments will only be made to domains on your list:

The domain allowlist restricts payments to only the specified domains.

Custom RPC Endpoints (Premium)

Use your own RPC nodes for better reliability or privacy. Leave blank to use the default public endpoints:

Configure custom RPC endpoints for each network.

Security Settings

The security panel provides options for protecting your wallet and managing keys:

Security settings for auto-lock, PIN management, and wallet backup.

Troubleshooting

Payment was blocked

Payments can be blocked for several reasons:

• Exceeds per-payment limit — the requested amount is higher than your max per-payment setting
• Daily limit reached — you've hit your daily spending cap
• Insufficient balance — not enough USDC in your wallet
• Domain not allowed — domain allowlist is enabled and the site isn't on your list
• Network disabled — the requested network is turned off in settings
• Rate limited — more than 10 payment requests from the same domain in one minute

Wallet won't unlock

• Make sure you're entering the correct PIN
• PINs are 4-6 digits only
• If you've forgotten your PIN, you'll need to wipe the wallet and restore from your recovery phrase

Balance shows $0.00

• Ensure you sent USDC on the Base network (not Ethereum mainnet or other chains)
• Check that the transaction has confirmed on-chain
• Try locking and unlocking your wallet to refresh the balance
• If using a custom RPC, verify the endpoint is working

Extension not detecting 402 responses

• Make sure your wallet is unlocked (green dot in header)
• Check that the toggle is enabled (not disabled)
• Refresh the page — the content script needs to inject on page load
• Some sites may use non-standard 402 implementations that aren't compatible

Premium features not unlocking

• Ensure you hold at least 100,000 PR tokens in the same wallet
• PR tokens must be on Base mainnet
• Click the refresh button (↻) in the Premium section to re-check your balance
• Premium status is cached for 5 minutes