95% of people in Spain use WhatsApp every day. The average engagement rate of a web chatbot is 30%. That figure alone should settle the debate, but it doesn’t. There are cases where a web chatbot performs better than WhatsApp, and choosing wrongly costs you money and conversions.
This guide sets out the real decision we make when a client asks us which channel to build first.
TL;DR
- WhatsApp wins in e-commerce, retail and high-ticket services where the customer wants an asynchronous conversation
- Web chatbot wins in SaaS, B2B consulting and cold leads who are still researching
- In 70% of cases, both channels are set up with the same brain behind them
Head-to-head comparison
| Criterion | WhatsApp Bot | Web Chatbot |
|---|---|---|
| Penetration in Spain | 95% daily | 100% browser, 30% engagement |
| Cost per conversation | 0.03-0.08 EUR | 0.001-0.01 EUR |
| Technical setup | Cloud API + dedicated number | Embed in a script tag |
| Response latency | 2-5 seconds | under 1 second |
| Average engagement | 70-85% completion | 25-35% completion |
| Re-engagement | Meta-approved templates | Limited push notifications |
| Asynchronicity | Full (customer closes and comes back) | Ephemeral session |
| CRM integration | Native with number/email | Cookie + optional email |
| Base monthly cost | 50-150 EUR API + templates | 0-30 EUR hosting |
WhatsApp is 30-50 times more expensive per conversation, but converts 2-3 times more. The maths usually works out in businesses with an average order value above 50 EUR.
When to choose a WhatsApp Bot
WhatsApp wins when at least one of these criteria is met:
- Your typical customer is on mobile rather than desktop
- The sales process involves back-and-forth over several hours or days
- You need to confirm an order, schedule a delivery or coordinate logistics
- You sell physical products with specific questions (size, colour, stock)
- Your sector is hospitality, healthcare, beauty, retail or local services
The classic case: an online fashion shop that receives 200 messages a day with sizing questions. A WhatsApp bot with a connected catalogue answers 80% of those questions, recommends products and sends the payment link. A human only steps in for exchanges and returns.
When to choose a web chatbot
A web chatbot wins when the customer is researching before buying:
- B2B SaaS where the lead reads the website for 10-20 minutes before requesting a demo
- Consulting or professional services with cold leads
- Low-ticket e-commerce (under 30 EUR) where the cost per conversation matters
- Organic SEO traffic where the visitor doesn’t want to leave their mobile yet
- Digital product support with a documented knowledge base
The classic case: a B2B SaaS tool with 5,000 organic visits a month. A web chatbot with RAG over the documentation answers 90% of technical questions and captures the email of the hot lead for the sales team.
Decision table by type of business
| Business | Recommended channel | Why |
|---|---|---|
| Fashion/home e-commerce | WhatsApp + Web | WhatsApp for after-sales, web for discovery |
| B2B SaaS | Web first | Organic traffic, leads researching |
| Hospitality / bookings | Customer wants asynchronicity and confirmation | |
| Consulting / agencies | Web + form | Cold leads, long cycle |
| Clinics and healthcare | Appointment booking, reminders, asynchronicity | |
| Estate agents | Photos, location, asynchronicity | |
| Online education | Web first | Discovery + enrolment |
For businesses with the budget, we recommend both channels connected to the same backend. The customer chooses where to talk, and the conversation keeps its context whichever channel they use.
The real technical stack
A decent WhatsApp Bot requires:
- WhatsApp Business API (Meta Cloud API or a BSP such as 360Dialog/Twilio)
- Verified dedicated number (a personal WhatsApp won’t work)
- Approved templates for starting conversations
- Webhook receiver with HMAC authentication
- Conversational model with session memory
A decent web chatbot requires:
- Embed script with lazy loading
- Backend with a vector database (pgvector works well)
- Conversational model with page context
- Optional email capture for handoff to a human
- Conversation analytics to improve prompts
What STAKKER SYSTEMS does in this area
We set up both channels with the same orchestration layer: the STAKKER AI chat assistant lives on your website and on your WhatsApp with the same brain behind it. The only difference between channels is the input connector. It responds 24/7, captures the lead and alerts you instantly.
Reference price: €25/month + a one-off €99 setup fee (excluding VAT, no minimum term), negotiable on contact; you’ll find the details on the pricing page. And if your leak is on the phone, the same approach exists for voice: an AI phone receptionist whose demo you can request via WhatsApp on 951 870 512.
The web bot is live in production on stakker.es. You can try it out on any page, at the bottom right.
Frequently asked questions
Do I need a dedicated WhatsApp number? Yes. The WhatsApp Business API requires a number that has never been used on any WhatsApp account before. Your personal number won’t do, nor will a recycled one.
How long does Meta take to approve the number? Between 24 and 72 hours if the documentation is in order. If your business isn’t registered as an SL (Spanish limited company) or autónomo (self-employed person in Spain), it can take weeks.
Can I switch from one provider to another without losing my number? Yes. A WhatsApp Business number is portable between BSPs. The switch takes 3-5 days.
Does the web chatbot slow down my site? If it’s properly implemented with lazy loading, it doesn’t affect Core Web Vitals. The one on stakker.es loads after the LCP.
Can I train the bot on my documentation? Yes. You upload PDFs, URLs or markdown and it is vectorised in pgvector. The bot answers by citing specific sources.
How much does a WhatsApp conversation cost with Meta? It depends on who starts it and the type of template. Customer-initiated conversations are cheaper (0.03-0.05 EUR). Business-initiated ones using a template cost 0.05-0.08 EUR.
Would you like to try our chatbot before deciding? It’s embedded on any page of stakker.es, or request the free diagnosis to see which channel makes sense for your business.