WhatsApp Bot Demo (Real Session)¶

Verified status as of March 28, 2026. Runtime note: FastFN auto-installs function-local dependencies from requirements.txt / package.json; host runtimes are required in fastfn dev --native, while fastfn dev depends on a running Docker daemon. This tutorial runs a real WhatsApp Web session from a function.

1. Start platform¶

docker compose up -d --build

2. Run the first demo (QR)¶

curl -sS 'http://127.0.0.1:8080/qr?text=HelloQR' -o /tmp/qr.svg

3. Open WhatsApp demo intro¶

curl -sS 'http://127.0.0.1:8080/whatsapp' | jq .

curl -sS 'http://127.0.0.1:8080/whatsapp?action=qr' --output /tmp/wa-qr.png

Open /tmp/wa-qr.png and scan from WhatsApp: - Settings - Linked devices - Link a device

5. Check session status¶

curl -sS 'http://127.0.0.1:8080/whatsapp?action=status' | jq .

Look for: - "connected": true - "me": "<jid>"

6. Send a message¶

curl -sS -X POST 'http://127.0.0.1:8080/whatsapp?action=send' \
  -H 'Content-Type: application/json' \
  --data '{"to":"15551234567","text":"hello from FastFN"}' | jq .

7. Read inbox/outbox¶

curl -sS 'http://127.0.0.1:8080/whatsapp?action=inbox' | jq .
curl -sS 'http://127.0.0.1:8080/whatsapp?action=outbox' | jq .

8. AI reply (optional)¶

Set API key in function env file:

<FN_FUNCTIONS_ROOT>/whatsapp/fn.env.json

{
  "OPENAI_API_KEY": {"value":"sk-...","is_secret":true},
  "OPENAI_MODEL": {"value":"gpt-4o-mini","is_secret":false}
}

Then:

curl -sS -X POST 'http://127.0.0.1:8080/whatsapp?action=chat' \
  -H 'Content-Type: application/json' \
  --data '{"to":"15551234567","text":"Write a short friendly reply in Spanish"}' | jq .

9. Reset session¶

curl -sS -X DELETE 'http://127.0.0.1:8080/whatsapp?action=reset-session' | jq .

Flow Diagram¶

flowchart LR
  A["Client request"] --> B["Route discovery"]
  B --> C["Policy and method validation"]
  C --> D["Runtime handler execution"]
  D --> E["HTTP response + OpenAPI parity"]

Objective¶

Clear scope, expected outcome, and who should use this page.

Prerequisites¶

FastFN CLI available
Runtime dependencies by mode verified (Docker for fastfn dev, OpenResty+runtimes for fastfn dev --native)

Validation Checklist¶

Command examples execute with expected status codes
Routes appear in OpenAPI where applicable
References at the end are reachable

Troubleshooting¶

If runtime is down, verify host dependencies and health endpoint
If routes are missing, re-run discovery and check folder layout