Hosuke for Welcart

Hosuke is an independent restock notification plugin designed specifically for Welcart e-Commerce. It is developed by Kobayashi Sharyo Co., Ltd. and is not officially affiliated with Welcart Inc.

When a shopper visits a product page whose SKU is currently sold out, Hosuke inserts a “Notify me when back in stock” button. The shopper enters their email address, and once the SKU’s stock transitions from 0 back to 1 or more, Hosuke automatically dispatches a notification email so the shopper can return to buy. Turns sold-out moments into recovered sales opportunities.

Key features

• SKU-level registration (works with both single-SKU and multi-SKU products)
• Automatic injection of the notify button next to the Welcart sold-out label via the standard usces_filters_single_sku_zaiko_message filter
• Real-time stock change detection on product save
• 15-minute WP-Cron background scan (catches stock changes made outside the admin UI)
• Three customizable email templates: registration confirmation, restock notification, admin alert
• [hosuke_restock_list] shortcode and sidebar widget to display recently restocked items
• Both guest and Welcart-member registration flows (member email auto-fills)
• Google reCAPTCHA v3 integration for spam protection
• Per-IP rate limiting on the registration endpoint
• Send queue with exponential-backoff retry (up to 3 attempts)
• Automatic cleanup of expired notifications
• GDPR / Japanese Personal Information Protection Act compliance via the WordPress Privacy Tools (Export / Erase)
• One-click unsubscribe for shoppers (via email link or Welcart my-page)
• CSV export from the admin panel
• WP-CLI command: wp hosuke send-queue
• REST API: POST /wp-json/hosuke/v1/send-queue, GET /wp-json/hosuke/v1/restock-list
• Japanese and English translation files bundled

Requirements

• WordPress 6.0 or higher
• PHP 7.4 or higher
• Welcart e-Commerce 2.9 or higher

About the author

Hosuke is developed and maintained by Kobayashi Sharyo Co., Ltd. as part of the kbsr product line for Welcart and WordPress.

Other kbsr products:

• Banto for Welcart — Amazon Pay V2 payment gateway + 5-carrier shipping label integration for Welcart (paid)
• Bunsuke — Japanese-focused AI writing assistance plugin for WordPress (paid)

See the full product lineup for details.

Privacy Policy

Hosuke stores the following personal data:

• Email address of subscribers
• Optionally, Welcart member ID (if the subscriber is logged in at registration time)
• Hashed IP address at registration (SHA-256, salted with WP nonce_salt)
• User agent string
• Timestamps: registration, notification sent, unsubscription

This data is used solely for the purpose of delivering the requested restock notification.

Data is automatically deleted after the configured retention period (default: 90 days after notification, 365 days for unfulfilled registrations).

WordPress Privacy Tools integration is provided for GDPR-style data export and deletion requests.

Third-Party Services

Hosuke can optionally integrate with Google reCAPTCHA v3 for spam protection.

• When enabled, the reCAPTCHA JavaScript library is loaded on product pages that display the notification button.
• The reCAPTCHA token is sent to Google’s servers for verification.
• Google’s terms and privacy policy apply: https://policies.google.com/privacy

This integration is off by default and must be explicitly enabled in Settings with your own site key and secret.