How to add group members in Python with the Wapito WhatsApp API

Before you start

• pip install requests
• os.environ["WAPITO_TOKEN"]
• A channel with a WhatsApp number linked to it, and its API token. Create one in the dashboard — the authentication guide shows where the token goes.

The whole script

Every step above in one runnable file. Save it as group-participants.py, put your token in the environment, and run it.

"""Group Participants with the Wapito WhatsApp API.

List who is actually in the group, add the missing people, remove the ones who left, and reconcile from the participants webhook.

Run it with:
    export WAPITO_TOKEN="wpt_..."
    python group-participants.py
"""
import os

import requests

BASE_URL = "https://api.wapito.com/v1"
TOKEN = os.environ["WAPITO_TOKEN"]

# --- Read the current membership ---
url = BASE_URL + "/groups/120363041234567890@g.us/participants"

headers = {"Authorization": "Bearer " + TOKEN}

response = requests.get(url, headers=headers)

print(response.json())

# --- Add the people who are missing ---
url = BASE_URL + "/groups/120363041234567890@g.us/participants"

payload = { "participants": ["+15551234567", "+15559876543"] }
headers = {
    "Authorization": "Bearer " + TOKEN,
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())

# --- Remove someone who has left the team ---
url = BASE_URL + "/groups/120363041234567890@g.us/participants/+15551234567"

headers = {"Authorization": "Bearer " + TOKEN}

response = requests.delete(url, headers=headers)

print(response.status_code)

Receive the webhook

FastAPI receiver for groups.participants — it verifies the signature, answers immediately and does the work after. Install it with pip install fastapi uvicorn and save it as webhook.py.

import hashlib
import hmac
import os
import time

from fastapi import FastAPI, Header, HTTPException, Request

app = FastAPI()
SECRET = os.environ["WAPITO_WEBHOOK_SECRET"].encode()
EVENTS = ["groups.participants"]


def verify(raw: bytes, header: str | None) -> bool:
    """Checks the X-Wapito-Signature header: t=<ms>,v1=<hex hmac-sha256>."""
    if not header:
        return False
    parts = dict(p.split("=", 1) for p in header.split(",") if "=" in p)
    ts, sig = parts.get("t"), parts.get("v1")
    if not ts or not sig:
        return False
    if abs(time.time() * 1000 - int(ts)) > 300_000:  # 5 minute clock skew
        return False
    expected = hmac.new(SECRET, ts.encode() + b"." + raw, hashlib.sha256).hexdigest()
    return hmac.compare_digest(expected, sig)


@app.post("/wapito")
async def wapito(request: Request, signature: str | None = Header(default=None, alias="X-Wapito-Signature")):
    raw = await request.body()
    if not verify(raw, signature):
        raise HTTPException(status_code=401, detail="bad signature")
    payload = await request.json()
    if payload["event"] in EVENTS:
        print(payload["event"], payload["data"])
    return {"ok": True}  # answer 2xx fast; do the real work in a queue

Errors you may hit

• invalid_request (400)
• forbidden (403)

Gotchas

• requests does not raise on a 4xx by itself. Call response.raise_for_status() or check response.ok, otherwise a 429 send_rate_limited silently looks like a successful send and your loop keeps hammering the queue.
• json= and data= are not interchangeable. Pass json={...} so requests sets Content-Type: application/json and encodes UTF-8 for you; data= with a dict sends form encoding and the API answers 400 invalid_request.
• The default requests timeout is None, which means a stalled connection hangs your worker forever. Always pass timeout=(5, 30) and treat a read timeout as "maybe delivered" - re-check with the message id before you send again.
• A group id such as 120363000000000000@g.us is a string, not a number. Building it with an f-string from an int drops the precision and you get 404 not_found.
• Emoji and accented text need no extra work in Python 3, but reading a CSV of numbers with the default encoding on Windows will mangle them - open files with encoding="utf-8".

Where to run it

• Google Cloud Run (container, scale to zero, one revision per deploy)
• Render background worker for the sender, Render web service for the webhook receiver
• A 1 GB VPS with systemd for the worker and Caddy in front of the FastAPI receiver
• AWS Lambda + API Gateway for the webhook receiver only (the sender needs a long-lived process for queue spacing)

Pitfalls in Python

• The per-participant result list is the truth and response.ok is not: requests reports success for the batch while individual entries say invited or failed. A script that only calls raise_for_status() will think everyone was added.
• A set difference on phone numbers silently misses people who appear as linked identities in the live list, so you add them again on every run. Key your comparison on the identity field the API returns, not on a number you reformatted.
• Removing members inside a for loop with no pause is the pattern most likely to look like an attack; add time.sleep between deletes and cap the number of removals per run in your own code.

Frequently asked questions

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