diff --git a/umap/static/umap/js/modules/global.js b/umap/static/umap/js/modules/global.js
index c7fce53f..2d579187 100644
--- a/umap/static/umap/js/modules/global.js
+++ b/umap/static/umap/js/modules/global.js
@@ -1,10 +1,21 @@
 import * as L from '../../vendors/leaflet/leaflet-src.esm.js'
 import URLs from './urls.js'
 import Browser from './browser.js'
+import * as Utils from './utils.js'
 import { Request, ServerRequest, RequestError, HTTPError, NOKError } from './request.js'
+
 // Import modules and export them to the global scope.
 // For the not yet module-compatible JS out there.
 
 // Copy the leaflet module, it's expected by leaflet plugins to be writeable.
 window.L = { ...L }
-window.U = { URLs, Request, ServerRequest, RequestError, HTTPError, NOKError, Browser }
+window.U = {
+  URLs,
+  Request,
+  ServerRequest,
+  RequestError,
+  HTTPError,
+  NOKError,
+  Browser,
+  Utils,
+}
diff --git a/umap/static/umap/js/modules/utils.js b/umap/static/umap/js/modules/utils.js
new file mode 100644
index 00000000..a5116616
--- /dev/null
+++ b/umap/static/umap/js/modules/utils.js
@@ -0,0 +1,24 @@
+/**
+ * Generate a pseudo-unique identifier (5 chars long, mixed-case alphanumeric)
+ *
+ * Here's the collision risk:
+ * - for 6 chars, 1 in 100 000
+ * - for 5 chars, 5 in 100 000
+ * - for 4 chars, 500 in 100 000
+ *
+ * @returns string
+ */
+export function generateId() {
+  return btoa(Math.random().toString()).substring(10, 15)
+}
+
+/**
+ * Ensure the ID matches the expected format.
+ *
+ * @param {string} string
+ * @returns {boolean}
+ */
+export function checkId(string) {
+  if (typeof string !== 'string') return false
+  return /^[A-Za-z0-9]{5}$/.test(string)
+}
diff --git a/umap/static/umap/js/umap.features.js b/umap/static/umap/js/umap.features.js
index fecbba57..57caecce 100644
--- a/umap/static/umap/js/umap.features.js
+++ b/umap/static/umap/js/umap.features.js
@@ -9,8 +9,17 @@ U.FeatureMixin = {
     // DataLayer the marker belongs to
     this.datalayer = options.datalayer || null
     this.properties = { _umap_options: {} }
+    let geojson_id
     if (options.geojson) {
       this.populate(options.geojson)
+      geojson_id = options.geojson.id
+    }
+
+    // Each feature needs an unique identifier
+    if (U.Utils.checkId(geojson_id)) {
+      this.id = geojson_id
+    } else {
+      this.id = U.Utils.generateId()
     }
     let isDirty = false
     const self = this
@@ -344,6 +353,7 @@ U.FeatureMixin = {
   toGeoJSON: function () {
     const geojson = this.parentClass.prototype.toGeoJSON.call(this)
     geojson.properties = this.cloneProperties()
+    geojson.id = this.id
     delete geojson.properties._storage_options
     return geojson
   },
diff --git a/umap/tests/integration/test_features_id_generation.py b/umap/tests/integration/test_features_id_generation.py
new file mode 100644
index 00000000..ca4558a5
--- /dev/null
+++ b/umap/tests/integration/test_features_id_generation.py
@@ -0,0 +1,51 @@
+import json
+from pathlib import Path
+
+
+def test_ids_generation(page, live_server, tilelayer):
+    page.goto(f"{live_server.url}/en/map/new/")
+
+    # Click on the Draw a line button on a new map.
+    create_polyline = page.locator(".leaflet-control-toolbar ").get_by_title(
+        "Draw a polyline"
+    )
+    create_polyline.click()
+
+    map = page.locator("#map")
+    map.click(position={"x": 200, "y": 200})
+    map.click(position={"x": 100, "y": 100})
+    # Click again to finish
+    map.click(position={"x": 100, "y": 100})
+
+    # Click on the Draw a polygon button on a new map.
+    create_polygon = page.locator(".leaflet-control-toolbar ").get_by_title(
+        "Draw a polygon"
+    )
+    create_polygon.click()
+
+    map = page.locator("#map")
+    map.click(position={"x": 300, "y": 300})
+    map.click(position={"x": 300, "y": 400})
+    map.click(position={"x": 350, "y": 450})
+    # Click again to finish
+    map.click(position={"x": 350, "y": 450})
+
+    download_panel = page.get_by_title("Share and download")
+    download_panel.click()
+
+    button = page.get_by_role("button", name="geojson")
+
+    with page.expect_download() as download_info:
+        button.click()
+
+    download = download_info.value
+
+    path = Path("/tmp/") / download.suggested_filename
+    download.save_as(path)
+    downloaded = json.loads(path.read_text())
+
+    assert "features" in downloaded
+    features = downloaded["features"]
+    assert len(features) == 2
+    assert "id" in features[0]
+    assert "id" in features[1]