The 24-hour window

This is the rule that shapes every integration, and it is Meta’s, not ours.

• Outside 24 hours of the customer’s last message to you, the only thing that will be delivered is an approved template.
• Inside that window, free text and media work too.

A free-text or media send with no open window is refused with 409 WINDOW_CLOSED before anything reaches Meta — you are not charged and nothing is queued.

Open the conversation with a template; once the customer replies, you have 24 hours of free-form messaging.

Asking rather than deriving

GET /conversations answers the question directly, per thread, as windowOpen — so you do not have to re-derive the rule from timestamps.

cURL

curl "https://vaarto.com/api/v1/conversations?perPage=20" \
  -H "Authorization: Bearer $VAARTO_API_KEY"

Node.js

const res = await fetch("https://vaarto.com/api/v1/conversations?perPage=20", {
  headers: { Authorization: `Bearer ${process.env.VAARTO_API_KEY}` },
});

const { data } = await res.json();

Python

import os, requests

res = requests.get(
    "https://vaarto.com/api/v1/conversations?perPage=20",
    headers={"Authorization": f"Bearer {os.environ['VAARTO_API_KEY']}"},
    timeout=10,
)

data = res.json()["data"]

PHP

$data = Http::withToken(env('VAARTO_API_KEY'))
    ->get('https://vaarto.com/api/v1/conversations', [
        'perPage' => 20,
    ])
    ->json('data');

Each thread carries lastInboundAt, lastOutboundAt and windowOpen. Branch on windowOpen, not on your own clock arithmetic — the window is Meta’s to define and it has moved before.