WhatsApp AI Bot in Production: 3 Months, 50K Messages, Zero Downtime

Source: Dev.to

The Challenge

My client had a problem: 200+ WhatsApp messages per day, 2 people answering, and still losing customers because response time was 2+ hours during peak times.

Their ask: “Can you make a bot that actually works?”

The Stack

WhatsApp Business API
        |
    Evolution API (self-hosted)
        |
    FastAPI Backend
        |
    Yoshii IA (Brazilian Portuguese LLM)
        |
    PostgreSQL + Redis

What Makes It Different

1. It Actually Understands Portuguese

Not translated English. Native Brazilian Portuguese.

Customer: "ce tem a blusa azul em P?"
(Informal: "u got the blue shirt in S?")

Bot: "Temos sim! A blusa azul ta disponivel em P, M e G.
     Quer que eu reserve pra voce?"

2. Smart Handoff

Bot handles 80 % of queries. Complex cases go to humans with full context:

if sentiment_score | Evolution API  |---->| Webhook  |
| Cloud API   |     | (self-hosted)  |     | Handler  |
+-------------+     +----------------+     +----------+
                                                |
                    +---------------------------+
                    |
              +-----v-----+     +---------+
              | Message   |---->| Yoshii  |
              | Processor |     | LLM API |
              +-----------+     +---------+
                    |
              +-----v-----+
              | Response  |
              | Generator |
              +-----------+
                    |
              +-----v-----+
              | Queue     |-----> Send via WhatsApp
              +-----------+

Cost Breakdown

Open Source

The LLM powering this is open source:

• Model: yoshii-ai/Yoshii-7B-BR
• Dataset: brazilian-customer-service-conversations

What’s Next

• Voice message processing (Whisper integration)
• Proactive messaging (order status updates)
• Multi‑language support
• Analytics dashboard

Building something similar? Happy to help in the comments!

sakaguchi.ia.br | WhatsApp