What it does

For stores that want to reach visitors who never leave an e-mail address. A soft permission card, a bell button or an alert button on the product page asks first; the browser prompt opens only after a click. Subscribers get your campaigns with title, text, image and link, and the alerts they asked for: back in stock and price drop. Uses the Web Push standard of Chrome, Edge, Firefox, Opera and Safari; tested end to end with Edge. On iPhone and iPad only after the store is added to the Home Screen.

How it works

Install

The VAPID keys are created for you. Choose how visitors subscribe: card after a delay, bell, both, or product buttons only. Open Marketing, Web push campaigns, write a title and text, add a link and an image, see the live preview, choose the audience and send now or at a set time. Product alerts are sent when a product comes back in stock or its price falls by your minimum. A cron job sends batches; Send queue now does it by hand. On 4.21 the add-on joins the core service worker next to the PWA add-on.

Features

Push notifications signed with your own VAPID keys, no push service account
Soft permission card, bell button and product alert buttons
Campaigns with title, text, link, large image and icon, with live preview
Send now or at a set date and hour; audience: all, signed-in customers or guests, by language and storefront
Back-in-stock and price-drop alerts with a minimum drop
Sent, failed, expired, clicks and click rate per campaign
Subscriber list with browser, device, alerts and a test message
Cron batches, retries for busy push services, expired browsers removed
Joins the CS-Cart 4.21 service worker next to the PWA add-on
Full page cache safe: the visitor's state lives in the browser

What you get

Package	kv_web_push-1.0.0.zip, installed through Add-ons → Manage add-ons
Updates & support	12 months included. Download new versions from your account and install them in Add-ons → Manage add-ons or the Upgrade Center.
License	1 production installation. Staging, dev and localhost are free and unlimited. The add-on keeps working after the update period ends. How licensing works

Compatibility

We list only the builds we install and test on. “Tested” means the full test plan was run on that build; “Supported” means the build is inside the supported range and uses the same hooks.

CS-Cart version and edition compatibility
CS-Cart version	CS-Cart	CS-Cart Ultimate	Multi-Vendor	Multi-Vendor Ultimate
4.22 and later	Testing next	Testing next	Testing next	Testing next
4.21.2	Supported	Supported	Supported	Supported
4.20.x	Supported	Supported	Supported	Supported
4.19.x	Supported	Supported	Supported	Supported
4.18.x	Supported	Supported	Supported	Supported
4.17.2	Tested	Supported	Tested	Supported
Before 4.17.2	Not supported	Not supported	Not supported	Not supported

Last tested build: Multi-Vendor 4.17.2, Nov 3, 2026Tested on: Multi-Vendor 4.17.2, CS-Cart 4.17.2

Requirements

PHP	CS-Cart or Multi-Vendor 4.17.2 to 4.21.x, PHP 7.4 to 8.3
PHP	PHP extensions `openssl` and `curl` (present on almost every host)
Requirement	HTTPS on the storefront. Browsers allow push only on secure pages
Requirement	A cron job (recommended) for scheduled campaigns, product alerts after imports and large lists
Core changes	None. Hooks and template overrides only

1.0.0

Nov 3, 2026

Latest

Added 6

Browser push notifications sent by the store itself: VAPID keys created on install, messages encrypted with aes128gcm, no push service account.
Permission card, bell button and product alert buttons; the browser prompt opens only after a click.
Campaigns with title, text, link, large image and icon, live preview, send now or at a set time, audience by customer type, language and storefront.
Back-in-stock and price-drop alerts with a minimum drop.
Counters for sent, failed, expired and clicks; subscriber list with test message.
Cron batches, retries, expired subscriptions removed; joins the CS-Cart 4.21 core service worker next to the PWA add-on.

Tested on Multi-Vendor 4.17.2, CS-Cart 4.17.2. First release.

Do I need a OneSignal, Firebase or other account?

No. The store signs every message with its own VAPID keys and sends it to the push service of the visitor's browser. The browser makers run these services without an account for this use.

Does it work on iPhone?

Only when the shopper has added your store to the Home Screen (iOS 16.4 or newer). In a normal Safari tab on iPhone and iPad web push is not available, so the add-on shows no card, bell or buttons there.

Why do I see no card on my store?

The storefront must use HTTPS. The card waits for the page view number and the delay you set, and it does not show after Not now (for the days you set), after the visitor blocked notifications, or for a browser that is already subscribed. Open the store in a private window to see it again.

Why does the click rate differ from my analytics?

A click counts once per message when the shopper clicks the notification. Analytics tools count visits.

Is my storefront still cached by the full page cache (4.21)?

Yes. The page holds only the public key and the texts, the same for every visitor; whether someone is subscribed is read in the browser.

We use the PWA add-on of CS-Cart 4.21. Is there a conflict?

No. On 4.21 the add-on adds its part to the core service worker that the PWA add-on uses too, so there is still one service worker and the offline page keeps working.

What happens when I create new keys?

All subscriptions stop working, because they were made for the old public key. Visitors must subscribe again. Only do it when the private key may have leaked.

Do vendors of Multi-Vendor get access?

No. Campaigns reach all subscribers of the marketplace, so only administrators with the promotions privilege manage them.

What is stored about subscribers?

The push endpoint and keys of the browser, the browser name, device type, language, the customer ID when signed in and a one-way hash of the address used for rate limiting. The add-on collects no e-mail address or name.

InstallationRequirements, Install, Cron job, Upgrade, Uninstall ConfigurationPrompt and storefront, Product alerts, Sending UsageDashboard, A campaign, Results, Subscribers, What shoppers see Developer notesService worker, Encryption, Storefront endpoints (POST, same site only), Hooks, Tables, Cron FAQ9 answers to common questions.

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What it does

How it works

Install

Features

What you get

Compatibility

Requirements

Added 6

Details

Support

What stands behind your license

Tested builds

12 months of updates

30-day refund

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