Primer Pay for WordPress

Monetize any WordPress post or page with x402 micropayments. Tick a box, set a price, publish. Readers with the Primer Pay browser extension unlock content instantly — everyone else sees a teaser with an install prompt.

How it works

1. You enable the paywall on a post and set a price (e.g. $0.01 USDC).
2. A reader visits the post. WordPress serves the teaser and a small unlock container.
3. Our JavaScript fires a fetch to the plugin's REST endpoint.
4. If the reader has the Primer Pay browser extension, it intercepts the 402 response, signs a USDC payment, and retries transparently.
5. The plugin validates the payment via the Primer facilitator, sets an HMAC-signed access cookie, and returns the unlocked content.
6. Subsequent visits are served from the cookie — no re-payment on refresh.

Readers without the extension see a teaser with a "Get Primer Pay" call-to-action linking to the Chrome Web Store.

Install

Requirements

• WordPress 5.8+ and PHP 7.4+
• A wallet address that can receive USDC payments on Base or SKALE Base (MetaMask, Coinbase Wallet, or the Primer Pay extension itself all work — same address works on all supported networks)
• HTTPS recommended — cookies are marked Secure on HTTPS sites; HTTP still works for local development

Setup

1. Install the plugin from the zip download above and activate it.
2. Go to Settings → Primer Pay and enter your wallet address.
3. Optionally adjust the default price, Access Duration, and Accepted Networks (Base, SKALE Base, or both — with a preferred-network priority).
4. Edit any post, find the Primer Pay box in the sidebar, check Enable x402 Paywall, and publish.

Marking the teaser

Add the [x402] shortcode anywhere in your post content. Everything above it is the free teaser; everything below is the paid content:

This is the free preview everyone sees.

[x402]

This is the paid content only visitors who pay can read.

If you don't add [x402], the plugin falls back to the post's excerpt as the teaser.

Readers: how to pay

Install the free Primer Pay browser extension, fund it with USDC on Base, and browse normally. Paywalled content unlocks automatically — no logins, no forms, no checkout flow.

Supported networks

Enable one or both in Settings → Primer Pay → Accepted Networks. When both are enabled, the preferred network is offered first; if the reader can't pay on it, the next is tried automatically. The same wallet address works on all networks.

Architecture highlights

REST-based unlock flow

Unlike naive x402 paywalls that return 402 on top-level navigation, Primer Pay serves paywalled posts as normal 200 OK pages and runs the x402 exchange via a background fetch() to a REST endpoint. This is compatible with:

• Hosts that insert interstitials or consent banners between the browser and the origin
• CDN bot-protection layers (Cloudflare, etc.)
• Browser content-script sandboxing (which blocks inline scripts in document.write-delivered content)
• Session cookies on unlock (which are discarded by the extension's navigation-path retry)

HMAC-signed access cookies

After a successful payment, the plugin sets an HttpOnly, HMAC-signed cookie scoped to that specific post. Subsequent visits within the configured duration skip the x402 dance entirely and serve the content directly. Cookies are:

• HMAC-SHA256 signed with a site-specific secret stored non-autoloaded in wp_options
• HttpOnly — not readable by JavaScript, preventing XSS exfiltration
• SameSite=Lax
• Verified in constant time via hash_equals()

Non-custodial

The plugin never handles private keys or funds. The merchant provides only a receive address; signing happens entirely in the reader's browser extension. Settlement happens through the Primer facilitator, which charges nothing for Base network transactions.

Planned

• Gutenberg block for inline content gating with editor preview
• Earnings dashboard and payment history export
• WooCommerce integration for digital downloads
• Multi-network support
• SIWX wallet identity for cross-post access passes
• REST API and media-file gating for headless WordPress and gated downloads

Support

Issues and pull requests welcome at github.com/primer-systems/primer-pay-wordpress. For direct contact, email dev@primer.systems.