Floating WhatsApp, Messenger or Telegram chat button with agent hours and an 'ask about this product' message.
Available Updated Oct 22, 2026Version 1.0.0CS-Cart, Multi-Vendor 4.17.2 – 4.21.x No core file edits
Built for
WhatsApp Chat Button: overview1 of 18
What it does
WhatsApp Chat Button lets shoppers reach you on the messenger they already use. One floating button opens WhatsApp, Messenger, Telegram, a phone call, an SMS or an e-mail, or a small panel with your agents and departments, each with a photo, a role and working hours in their own time zone. Product pages get an Ask about this product button, the cart and checkout a help link. For any store that sells by conversation, and for marketplaces where vendors answer on their own number.
How it works
Enter your WhatsApp number and other channels in the settings, pick the position, colours and pages. In Marketing, WhatsApp chat add agents with their channel and weekly hours. The visitor clicks the button: one contact opens at once, several open the panel with online states and Back at times. The message is typed in, the visitor sends it from their own app. No third-party script is loaded and the page is cache-friendly. Multi-Vendor vendors set their own number in the vendor panel.
Features
One button for WhatsApp, Messenger, Telegram, phone, SMS and e-mail
Agents and departments with photo, role, channel and working hours in their own time zone
Back at times outside working hours, or hide offline agents
Rotation between the agents who are online
Ask about this product with product name, SKU, selected options and link
Cart and checkout help link with the cart lines and total
Position, offsets, colours, size, label, greeting bubble and pages
Moves above sticky add-to-cart bars, bottom menus and cookie notices
Click statistics per day, channel, agent and page, GA4 and Tag Manager events
Multi-Vendor: vendors answer on their own WhatsApp number, full page cache ready (4.21)
What you get
Package
kv_whatsapp_chat_button-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
For developers
Uses 7 CS-Cart PHP hooks. No core files are changed.
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: CS-Cart 4.17.2, Oct 22, 2026Tested on: CS-Cart 4.17.2, Multi-Vendor 4.17.2
Requirements
Platform
CS-Cart 4.17.2 – 4.21.x, or CS-Cart Multi-Vendor 4.17.2 – 4.21.x
PHP
PHP 7.2.5 – 8.3, as supported by your CS-Cart version
Theme
A storefront theme based on Responsive (Responsive, Bright, Nova and most third-party themes)
Platform
A license key from cs-cart.kaviolabs.com or a CS-Cart Marketplace license number
Core changes
None. Hooks and template overrides only
1.0.0
Oct 22, 2026
Latest
Added 10
Floating chat button for WhatsApp, Facebook Messenger, Telegram, phone, SMS, e-mail and (with Help Desk & Support Tickets) a support ticket link; one contact opens directly, several open a chat panel.
Agents and departments in Marketing > WhatsApp chat: name, role, photo, channel, contact, own pre-filled message, weekly working hours in the agent's time zone; "Back at ..." or hidden outside working hours; list or rotate mode.
"Ask about this product" button on product pages with product name, SKU, selected options and link in the message.
Help link on the cart and checkout pages with the cart lines and the total in the message.
Click statistics per day, channel, agent, place and (Multi-Vendor) vendor; counts only.
GA4 / Google Tag Manager events (kv_chat_open, kv_chat_click), via Ecommerce Tracking Pro when active; optional wait for cookie consent (Cookie Consent by Kavio Labs).
Multi-Vendor: vendors' own WhatsApp number, message and hours in the vendor panel, shown on their products and store page, with their own click statistics.
CS-Cart Ultimate: settings per storefront, agents shared or per storefront.
Full page cache support (4.21): same HTML for every visitor, online states computed in the browser.
Tested on CS-Cart 4.17.2, Multi-Vendor 4.17.2. First release.
Do I need a WhatsApp Business account or an API key?
No. The button uses the public click-to-chat links of WhatsApp (wa.me), Messenger (m.me) and Telegram (t.me). Any WhatsApp or WhatsApp Business number works. Messages arrive in your normal app.
Does it work with Multi-Vendor?
Yes. Vendors can enter their own WhatsApp number in the vendor panel; their product pages and store page then show the vendor first and your store support as the fallback. Vendors see their own click counts.
Which CS-Cart versions are supported?
4.17.2 to 4.21.x, CS-Cart (including Ultimate) and Multi-Vendor, PHP 7.2.5 to 8.3.
Will it slow down my store?
No. The add-on loads no third-party script: the button is a small script and stylesheet bundled with the store's own files, and nothing is requested from WhatsApp or any other service before the visitor clicks. The page HTML is the same for every visitor, so the full page cache of CS-Cart 4.21 keeps working.
Do I need cookie consent for the button?
Usually not: it sets no cookie and loads nothing from third parties (a session storage flag only remembers a closed greeting). If your privacy policy requires it, set Wait for cookie consent and the button stays hidden until the visitor allows Preferences or Marketing in our Cookie Consent add-on.
Can I show different people for sales and support?
Yes. Add agents or departments in Marketing → WhatsApp chat with their own number, role, photo and working hours. Use Rotate to spread visitors over the agents who are online.
What happens outside working hours?
Offline agents show when they are back ("Back tomorrow at 08:00") and can still receive a message, or they are hidden (Outside working hours setting). Working hours are kept in each agent's time zone, so visitors anywhere see the right state.
The button covers my sticky add-to-cart bar or bottom menu.
Keep Move above sticky bars automatically on: the button moves above fixed bars at the bottom of the screen while they are visible. You can also change the offsets or use Bottom left.
I already use another chat widget (for example Re:plain).
Both can run. Put the chat button at the bottom left, or hide the floating button and keep only Ask about this product and the cart help link (uncheck all pages in Show the floating button on).
Is the message sent automatically?
No. The chat opens with the message typed in; the visitor can change it and sends it themselves.
How do I get updates?
Updates are free during your updates and support period (12 months, extendable). Download the new version from your account on cs-cart.kaviolabs.com or install it from the Upgrade center, and upload it over the installed one. Settings, agents and statistics are kept.
What happens without a valid license?
Without a valid license (no key after the 14-day start period, an invalid or revoked key, a domain the license does not cover, or no successful check for 14 days), the chat button, the "Ask about this product" button and the cart help link are hidden on the storefront and no new clicks are counted; agents, settings and statistics stay in the admin panel. Once the license is valid again, everything is back.
The admin panel shows a license notice.
Open Add-ons → Manage add-ons → WhatsApp Chat Button: the License card at the top says what is wrong. Fix it on the License tab and click Check now. See License.
Does the add-on work on my staging copy?
Yes. Subdomains of your licensed domain and local development hosts (localhost, private IP addresses, .local, .test) are covered by the same license.
What happens if your license server is down?
Nothing changes for 14 days: the add-on keeps working and retries every hour. Only if no check succeeds for 14 days is it switched off until the next successful check.
Does the license check slow down my storefront?
No. The check runs only in the admin panel or from cron, at most once a day, never while customers browse or check out.
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