Off-Nadir Delta
Copernicus Browser Alternative

A Copernicus Browser Alternative — For When Browsing Is Not the Job

Copernicus Browser is free, official, and good at what it does. Off-Nadir Delta is what you reach for when the question is not “show me this place” but “tell me where to look, watch it for me, and explain what changed.”

Quick answer — what Off-Nadir Delta is

Copernicus Browser is ESA’s free official browser for Copernicus Sentinel data, and it remains the right tool for browsing, custom evalscripts, timelapse, and downloading the original products. It is not built to tell you where to look or to keep watching for you. Off-Nadir Delta is a complementary alternative for that half of the job: a geolocated world-event layer surfaces the area, Sentinel-1 SAR and Sentinel-2 optical confirm it, an AI analyst explains it with cited sources, and an area you draw is re-measured on every new pass with anomaly alerts. Free tier available.

Copernicus Browser vs Off-Nadir Delta, side by side

Facts last reviewed 2026-08-23.

CapabilityCopernicus BrowserOff-Nadir Delta
CostFreeFree tier; paid plans
Browse and visualize Sentinel scenes in the browserYesYes
Compare dates and build a timelapseYesYes
Custom server-side scripts (evalscript)YesNo
Download the original Sentinel productYesNo
Geolocated world-event layer telling you where to lookNoYes
Area re-measured automatically on every new passNoYes
Anomaly alerts against the area’s own historyNoYes
AI analyst brief with cited sourcesNoYes
Best forBrowsing, scripting and downloading Sentinel dataBeing told where to look, then watching it

Both run on the same open Copernicus Sentinel data, so this is a difference in purpose rather than in data. Copernicus Browser is developed under the governance of ESA and the European Commission; Off-Nadir Delta is an independent project and is not affiliated with ESA, the European Commission, or the Copernicus programme.

Which one do you need?

Stay with Copernicus Browser if…

You already know the coordinates, you want the official free viewer for the full Copernicus catalog, you write your own evalscripts, or you need to download the original product to process it somewhere else. It is free and it is the reference implementation.

Add Off-Nadir Delta if…

You do not yet know where to look, you need the area watched between visits rather than re-checked by hand, or you want an analyst’s reading of an event — with sources — next to the imagery rather than in your head.

The area finds you

The Watchfloor maps geolocated world events ranked by severity, so you start from a signal rather than from a coordinate you had to already know.

Watching between visits

Draw an area once and it is measured again on every new pass, with an anomaly alert when the value departs from its own history — not a manual re-check.

SAR when optical fails

Sentinel-1 C-band SAR sees through cloud and works at night, so a cloudy or nighttime event is still observable. Sentinel-1 is on paid plans.

An analyst, not just pixels

Delta Agent answers why an event matters and which sensor and area to image next, and cites the sources behind each claim.

A time series, kept

Each monitored area accumulates its own measured history, so “is this unusual?” has a baseline to answer against.

Same data, no install

The same open Copernicus Sentinel archive, in the browser, with no scripting required to get a usable visualization.

How It Works

1

Start from an event, not a coordinate

The Watchfloor maps geolocated world events ranked by severity, so the signal picks the area of interest instead of you guessing where to pan.

2

Pull imagery over it

Open Sentinel-2 optical or Sentinel-1 SAR over the event and compare dates — the same core browsing workflow, in the browser, with no scripting.

3

Ask what it means

Delta Agent answers in plain language, recommends which sensor and area to image next, and cites its sources.

4

Leave it watching

Draw an area and it is measured again on every new pass, with anomaly alerts when the value departs from its own history.

Frequently Asked Questions

Do I actually need a Copernicus Browser alternative?
For browsing, visualizing, and downloading Sentinel data, no — Copernicus Browser is free, developed under ESA and European Commission governance, and it covers that job well, including custom scripts (evalscripts), timelapse animation, and time-series inspection. You need something different when the question is not "show me this place" but "tell me where to look, watch it for me, and explain what changed." That is where Off-Nadir Delta fits, and the two are complementary rather than substitutes.
What does Off-Nadir Delta add that Copernicus Browser does not?
Three things. A geolocated world-event layer (the Watchfloor) that surfaces the area of interest instead of requiring you to already know the coordinates. Automated area monitoring that re-measures your polygon on every new satellite pass and raises an anomaly alert when the value departs from its own history — as opposed to you re-opening the browser and looking again. And an AI analyst that answers questions about an event with cited sources and recommends which sensor and area to image next.
What does Copernicus Browser still do better?
Downloading the original Sentinel products, custom evalscripts, and breadth of the official Copernicus catalog. If your workflow depends on pulling the raw product for processing elsewhere, or on writing your own server-side visualization scripts, use Copernicus Browser — Off-Nadir Delta does not replace it and does not try to.
Is Off-Nadir Delta free?
There is a free tier. Pricing is token-based for imagery rendering and processing. Sentinel-2 optical viewing and area monitoring are included on the free tier; Sentinel-1 SAR, VIIRS nighttime lights, and change detection are on paid plans. The pricing page has the current split.
Can I use both together?
Yes, and that is the common pattern. Use Off-Nadir Delta to find which area and date matter and to keep watch on it, then go to Copernicus Browser when you need to download the original product or script a custom visualization. Both run on the same open Copernicus Sentinel data.
Does it require an account or installation?
No installation — it runs in the browser. You can browse the public Watchfloor without an account; opening imagery on the map, saving your work, and area monitoring need an account, and a free one is enough to start.

Start from what is happening, not from a coordinate

Open the Watchfloor to see geolocated world events ranked by severity, then pull Sentinel imagery over any of them. Free to browse, no account needed to look.

From headline to satellite evidence

One connected intelligence workflow across four surfaces — free to start, no GIS software or remote-sensing background required.