Placing a WhatsApp button on the website takes five minutes. The difficult part comes after the tap: who responds, how quickly, with what information and what happens when the message arrives at eleven at night. For anyone who visits the site, the button is a promise of conversation. If no one delivers on this promise, the button becomes just another way to lose the customer, now with the conversation history showing that they tried.
This guide separates the two parts: the button, which is technical, and the customer service, which is operational.
Why WhatsApp became the main point of contact
The ICT Households 2025 survey, by Cetic.br, shows that 92% of internet users in Brazil sent instant messages, a proportion stable since 20231. In the same survey, 65% went online only through a cell phone1. For many people, sending a message is less work than calling or filling out a form.
This changes how much the button matters. If your customer prefers to send a message, the button stops being an extra channel and becomes the main one. And a front door with no one behind it costs more than a forgotten form.
What visitors expect when they tap
Anyone who taps the button expects a reply. Nielsen Norman Group, in its guidelines for chat support, recommends showing service hours when chat is not staffed around the clock and making it clear when a bot is responding, so people can adjust their expectations2. The same guidelines ask that the company never ask for the same information twice in the same conversation2.
Speed also matters. A study published in Harvard Business Review in 2011 concluded that most companies did not respond to contacts received over the internet quickly enough3. The practical lesson is simple: define a response time that your team can meet every day and say what it is. Promising "immediate response" and responding the next day is worse than saying "we respond within two hours, Monday to Friday".
The button: how to set it up correctly
The official WhatsApp link to start a conversation is https://wa.me/ followed by the number in full international format. The WhatsApp help center advises you to omit zeros, parentheses and dashes4. For a number in Campinas, for example, it becomes https://wa.me/5519XXXXXXXXX: 55 for Brazil, 19 for the area code (DDD) and the number. According to WhatsApp, the link works both on phones and on WhatsApp Web4.
Three adjustments make a difference:
- A pre-filled message for each page. Adding
?text=to the link, with the encoded text (the spaces become%20), the message appears already typed in the text box4. Use one per service page: "Hi! I came from the air conditioning maintenance page and would like a quote." The customer doesn't face a blank screen, and you know where they came from. - Right place. NN/g recommends making chat access prominent on contact pages and product or service pages2. On mobile, check that the floating button does not cover text, forms or the cookie notice.
- Hours next to the button. One line is enough: “Customer service Monday to Friday, 8 a.m. to 6 p.m.”
If you prefer the official "Chat on WhatsApp" button, WhatsApp requests that it be used unchanged, in the latest version, following brand guidelines4.
In practice
List your service pages and write a pre-filled message for each one, always mentioning the service. In one afternoon, every new conversation starts arriving with its source identified.
Customer service: what happens after the tap
The WhatsApp Business app, made for small businesses, already has the basic tools to turn the button into real customer service5. These are all settings within the app itself.
Complete business profile. Logo, short description, opening hours and website, gathered in one place for the customer to consult before writing5.
Greeting message. Automatically sent to new customers who start a conversation with the company5. Use it to say who responds and how soon, not to dump a menu of options on people.
Away message. Automatically replies outside business hours and says when the business will be back5. It's what separates a "no one responded to me" from a "they told me they'll respond tomorrow at 8am".
Quick replies. Shortcuts for messages you send frequently5: address, payment methods, how the first visit works, necessary documents. Use as a starting point and customize before sending.
Labels. Organize conversations by stage5, such as "new contact", "quote sent", "awaiting reply" and "customer". For a small business, they work as a bare-bones sales tracker, without a spreadsheet.
In practice
Write down the five questions you get most often on WhatsApp this week. Turn each answer into a quick reply and revise the away message to include the exact time you will reply.
A button alone or full customer service
| Button alone | Button with customer service | |
|---|---|---|
| First message | Blank screen | Pre-filled message mentioning the service |
| After hours | Silence | Away message with reply time |
| Repeat questions | Answered from scratch, every time | Revised quick replies |
| Follow-up | Depends on the memory of the person answering | Labels by stage |
| Origin of contact | Unknown | Identified by the pre-filled message |
When the app is no longer enough
If only a few people handle replies, the app may be enough. According to the official page, with Meta Verified you can connect up to ten devices and agents to the same account5. When volume grows or customer service needs to integrate with other systems, such as a calendar and customer management, the way forward is the WhatsApp Business Platform, Meta's API, which requires technical integration, carried out by the company itself or by a provider.
It works under different rules. Since July 1, 2025, Meta charges per message sent from templates (marketing, utility and authentication)6. When the customer writes, a 24-hour customer service window opens, and regular messages sent within it are free of charge6. Outside this window, you can only send pre-approved templates7.
Signs that the platform is worth looking into: two people answering the same customer without knowing it, appointments retyped by hand from a chat into the calendar, and conversations lost among hundreds of others.
Outbound messages require permission
Replying to someone who reached out is customer service. Messaging someone who didn't ask is something else. Meta's policy requires opt-in: the person must have provided their number and confirmed that they want to receive messages from that company. The request must make clear that they are agreeing to receive communications and name the company. The policy also requires compliance with applicable law8.
In Brazil, this law includes the LGPD. Name, phone number and the content of conversations are personal data. In clinics and practices, what the patient says over WhatsApp is often health data, which the law classifies as sensitive personal data (art. 5, II)9. Three practical precautions:
- Ask only for what you need for the first contact. The LGPD calls this the necessity principle (art. 6, III)9.
- Define who has access to the device and conversations. The law requires security measures to protect data (art. 46)9.
- Do not add contacts to broadcast lists without confirmation that the person wants to receive them.
How to tell whether WhatsApp is bringing in customers
Google Analytics 4 automatically records clicks on links that lead away from the site, including the link address10. Mark the click on WhatsApp as a key event and track how many people tap the button on each page. The article on how to know if your website is losing customers shows this step by step.
Then close the loop within WhatsApp itself:
| What to measure | How | How often |
|---|---|---|
| Button taps per page | GA4, key event | Monthly |
| Conversations by service | Pre-filled message for each page | Monthly |
| Conversations that turned into a quote | "Quote sent" label | Weekly |
| Time to first response | Sample of 10 conversations from the week | Weekly |
| Unanswered conversations | Unread filter at the end of the day | Daily |
Checklist
- Check if the link uses the number in international format, without zeros, parentheses or dashes.
- Test the button on your cell phone and computer.
- Create a pre-filled message for each service page.
- Write opening hours next to the button.
- Complete the business profile with description, hours and website.
- Activate the greeting and away message, with the return time.
- Create quick replies for the five most frequently asked questions.
- Organize conversations with labels by stage.
- Mark the WhatsApp click as a key event in GA4.
- Review who accesses conversations and what is asked of the customer.
The button is the easy part
A well-built button takes the customer to the conversation. The rest depends on response, clarity and follow-through. If you want to know how your website leads someone to that first contact, and where that path breaks down, Flowt's free diagnosis measures digital presence with fixed criteria and shows, point by point, where it loses customers.
