Get notified in your own system when a watched place changes
You follow a facility, an area or an event and want each change pushed into your own tooling — a ticket, a dashboard, an alert channel — instead of someone checking a screen or a script polling for it.
Steps
- Watch the place: a site (a registry facility or any point, at facility, city or country scale), an area or an event. Watches are free.
- Register your https endpoint as the notification channel and keep the signing secret — it is returned only once.
- Turn on notify_chat for the watches you want delivered, then send a test delivery to check the receiver.
- In the receiver, verify X-Delta-Signature over the raw body and reject an old timestamp. Each change says what moved, with its value before and after where your plan opens it.
- Deliveries run with the hourly notifications. If the receiver was down, ask for a replay (up to 7 days per call): every change carries its ledger id, so one you already have is recognised.
In the web app
REST
Authenticate with Authorization: Bearer ond_… (create a key at /account/api). Try any of these live in the Playground.
Watch a site (free)
bash
curl "https://offnadir-delta.com/api/v1/watches" \
-X POST \
-H "Authorization: Bearer ond_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"target_type":"site","lat":46.49,"lon":30.74,"scale":"facility","name":"Odesa port"}'Register the webhook (free; the signing secret is returned once)
bash
curl "https://offnadir-delta.com/api/v1/notification-channel/webhook" \
-X POST \
-H "Authorization: Bearer ond_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"url":"https://example.com/delta-hook"}'Send a test delivery (free)
bash
curl "https://offnadir-delta.com/api/v1/notification-channel/test" \
-X POST \
-H "Authorization: Bearer ond_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{}'Replay what the receiver missed (free)
bash
curl "https://offnadir-delta.com/api/v1/notification-channel/replay" \
-X POST \
-H "Authorization: Bearer ond_YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"since":"2026-10-18T00:00:00Z"}'Python
This is the runnable example shipped with the SDK (pip install offnadir-delta, then set OFFNADIR_DELTA_API_KEY).
python
"""Receive watch notifications on your own endpoint and verify each delivery.
1. Register the endpoint once (it must be https on port 443 and reachable from the internet —
run this behind your reverse proxy or a tunnel):
from offnadir_delta import Client
with Client() as client:
channel = client.notifications.channel.connect_webhook("https://example.com/delta-hook")
print(channel.signing_secret) # returned only once — store it
2. Turn on notifications for the watches you want delivered (the watch's notify_chat setting,
in the app or with client.watches.update).
3. Run this receiver: DELTA_WEBHOOK_SECRET=whsec_... python examples/webhook_receiver.py
Deliveries run with the hourly notifications. Each change has a ledger id, so a change sent
again by notifications.channel.replay() is recognised and skipped.
"""
import os
from http.server import BaseHTTPRequestHandler, HTTPServer
from offnadir_delta import WebhookSignatureError, verify_webhook
SECRET = os.environ["DELTA_WEBHOOK_SECRET"]
PORT = int(os.environ.get("PORT", "8080"))
# Ids of changes already handled. Keep these in your database in a real receiver.
seen: set = set()
class DeltaWebhook(BaseHTTPRequestHandler):
def do_POST(self) -> None:
raw = self.rfile.read(int(self.headers.get("Content-Length", "0")))
try:
# The raw bytes, exactly as received — parsing and re-serialising would change them.
event = verify_webhook(raw, self.headers.get("X-Delta-Signature"), SECRET)
except WebhookSignatureError as exc:
self.send_response(400)
self.end_headers()
print(f"rejected: {exc}")
return
if event.get("type") == "test":
print("connected:", event.get("message"))
else:
watch = event["watch"]["name"]
for change in event["changes"]:
if change["id"] in seen:
continue # already handled (for example, sent again by a replay)
seen.add(change["id"])
# `line` is always present; label / from / to are null when your plan does not open them.
print(f"[{watch}] {change['line']}")
# Answer 2xx quickly. A 404 or 410 stops the channel; other errors are retried each hour.
self.send_response(204)
self.end_headers()
if __name__ == "__main__":
print(f"listening on :{PORT}")
HTTPServer(("", PORT), DeltaWebhook).serve_forever()
MCP
Connect once, from any MCP client:
bash
claude mcp add --transport http off-nadir-delta \
https://offnadir-delta.com/api/v1/mcp \
--header "Authorization: Bearer ond_..."The tools this workflow uses: create_watch, update_watch, list_notifications. See the full roster at /docs/mcp.
Go deeper
From headline to satellite evidence
One connected intelligence workflow across four surfaces — free to start, no GIS software or remote-sensing background required.