diff --git a/docs/zones-api.md b/docs/zones-api.md
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+# Zones API
+
+The Zones API lists MeshMapper regions and serves their boundaries as GeoJSON. Use it to show MeshMapper regions on your own map, link to them, or keep a local copy of their outlines. No key is needed.
+
+Two endpoints work together:
+
+1. **`get_zones.php`** on meshmapper.net lists the regions in one country, without boundaries.
+2. **`get_geojson.php`** on each region's own site returns that region's boundary.
+
+Call the first one, then fetch `url + "get_geojson.php"` for each region you want.
+
+!!! note "Fair use"
+    Both endpoints are public, cached for an hour, and rate limited to 60 requests per minute per IP address (shared between the two). Cache the results, respect `ETag`, and don't poll more than once an hour. Accessing anything that isn't a published API, or scraping pages for data, is not allowed; see the warning on the [Coverage API](coverage-api.md) page.
+
+## List regions
+
+```
+GET https://meshmapper.net/get_zones.php?country=CA
+```
+
+| Parameter | Required | Description |
+| --- | --- | --- |
+| `country` | Yes | Two-letter country code (ISO 3166-1 alpha-2, e.g. `CA`, `US`, `GB`). Case doesn't matter. |
+
+Only enabled regions are listed. Regions that are pending or turned off never appear.
+
+### Response
+
+```json
+{
+  "generated_at": "2026-09-25T15:00:00Z",
+  "country": "CA",
+  "count": 3,
+  "zones": [
+    { "code": "YOW", "name": "Ottawa, CA", "short_name": "Ottawa", "country": "CA",
+      "lat": 45.4215, "lon": -75.6972, "url": "https://yow.meshmapper.net/",
+      "has_boundary": true, "group": null },
+    { "code": "YVR", "name": "Vancouver, CA", "short_name": "Vancouver", "country": "CA",
+      "lat": 49.2827, "lon": -123.1207, "url": "https://yvr.meshmapper.net/",
+      "has_boundary": true, "group": "PNW" },
+    { "code": "YQB", "name": "Quebec City, CA", "short_name": "Quebec City", "country": "CA",
+      "lat": 46.8139, "lon": -71.208, "url": "https://yqb.meshmapper.net/",
+      "has_boundary": false, "group": null }
+  ],
+  "groups": [
+    { "code": "PNW", "name": "Pacific Northwest", "members": ["SEA", "YVR"],
+      "url": "https://pnw.meshmapper.net/" }
+  ]
+}
+```
+
+### Zone fields
+
+| Field | Description |
+| --- | --- |
+| `code` | Region code, uppercase. Usually three letters, but can be 2 to 6 letters or digits. |
+| `name` | Region name as MeshMapper stores it, including the country suffix. |
+| `short_name` | `name` without the `, CC` country suffix. |
+| `country` | Two-letter country code. |
+| `lat`, `lon` | The region's center point. |
+| `url` | The region's MeshMapper site. Append `get_geojson.php` for its boundary. |
+| `has_boundary` | `true` when the region has a drawn boundary. When `false`, `get_geojson.php` returns the region with `geometry: null`. |
+| `group` | The multi-region group this region belongs to (see [Multiregions](multiregions.md)), or `null`. |
+
+### Group fields
+
+`groups` lists each group that contains at least one of the listed regions. `members` is the group's full member list, which can include regions from other countries (`SEA` above).
+
+| Field | Description |
+| --- | --- |
+| `code` | Group code, uppercase. |
+| `name` | Group name. |
+| `members` | Region codes in the group. |
+| `url` | The group's MeshMapper site. Its `get_geojson.php` returns every member. |
+
+## Region boundary
+
+```
+GET https://yow.meshmapper.net/get_geojson.php
+```
+
+Returns a GeoJSON `FeatureCollection` ([RFC 7946](https://datatracker.ietf.org/doc/html/rfc7946)):
+
+- On a **region** site: one Feature, for that region.
+- On a **group** site (e.g. `pnw.meshmapper.net`): one Feature per member region.
+
+```json
+{
+  "type": "FeatureCollection",
+  "generated_at": "2026-09-25T15:00:00Z",
+  "features": [
+    {
+      "type": "Feature",
+      "geometry": {
+        "type": "Polygon",
+        "coordinates": [[
+          [-75.912345, 45.201234], [-75.401234, 45.198765],
+          [-75.398765, 45.612345], [-75.912345, 45.201234]
+        ]]
+      },
+      "properties": {
+        "code": "YOW", "name": "Ottawa, CA", "short_name": "Ottawa", "country": "CA",
+        "center": [-75.6972, 45.4215], "radius_km": 42, "has_boundary": true,
+        "url": "https://yow.meshmapper.net/"
+      }
+    }
+  ]
+}
+```
+
+- Coordinates are `[longitude, latitude]`, as GeoJSON requires, rounded to 6 decimals (about 10 cm). The outline is never simplified.
+- The geometry is always a single `Polygon`.
+- A region with no drawn boundary has `"geometry": null` and `has_boundary: false`. MeshMapper doesn't draw a circle in its place, but `center` and `radius_km` are there if you want one.
+- `center` is `[longitude, latitude]` too.
+
+## Caching
+
+Both endpoints send `Cache-Control: public, max-age=3600` and an `ETag`. To check for changes cheaply, send the `ETag` back in `If-None-Match`; you'll get `304 Not Modified` with no body if nothing changed. `generated_at` changes on every response and isn't part of the `ETag`.
+
+## Errors
+
+Errors are JSON: `{"error": "<code>"}`.
+
+| Status | `error` | Meaning |
+| --- | --- | --- |
+| 400 | `country_required` | `get_zones.php` was called without `country`. |
+| 400 | `invalid_country` | `country` isn't two letters. |
+| 404 | `zone_not_found` | The region is unknown, pending or turned off. |
+| 429 | `rate_limited` | Over 60 requests in a minute. Wait for the `Retry-After` header (seconds). |
+| 503 | `unavailable` | Temporary server problem. Try again later. |
+
+## Example
+
+Fetch every Canadian region with a boundary into one GeoJSON file:
+
+```python
+import json, httpx
+
+zones = httpx.get("https://meshmapper.net/get_zones.php", params={"country": "CA"}).json()
+features = []
+for z in zones["zones"]:
+    if z["has_boundary"]:
+        fc = httpx.get(z["url"] + "get_geojson.php").json()
+        features.extend(fc["features"])
+json.dump({"type": "FeatureCollection", "features": features}, open("meshmapper-ca.geojson", "w"))
+```
diff --git a/mkdocs.yml b/mkdocs.yml
index 300c67c..6af0bdb 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -46,6 +46,7 @@ nav:
     - Admin Portal: admins.md
     - Webhooks: webhooks.md
     - Coverage API: coverage-api.md
+    - Zones API: zones-api.md
     - Data Upload: dataupload.md
   
   - Support: