diff --git a/src/App.svelte b/src/App.svelte
index 2144c25..8d30934 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -67,6 +67,9 @@
     updateColors()
   }
   let upload: Checkpoint | null
+  let autoSave: Checkpoint | null = JsonTy.lsRead(`${pid}-auto-save`)
+  if (autoSave) restorePt(autoSave)
+  setInterval(() => { JsonTy.lsWrite(`${pid}-auto-save`, autoSave = ckpt()) }, 30 * 1000)
 
   // Run something on the edges of a cell
   function updateEdges(x: number, y: number, condition: (st: number) => boolean, op: (st: number) => number) {
diff --git a/src/utils.ts b/src/utils.ts
index 7c3107a..66c52f3 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -59,6 +59,10 @@ export const JsonTy = {
     URL.revokeObjectURL(a.href)
   },
 
+  lsRead: (key: string) => {
+    let v = localStorage.getItem(key)
+    return v ? JsonTy.parse(v) : null
+  },
   lsWrite: (key: string, obj: any) => localStorage.setItem(key, JsonTy.stringify(obj)),
   lsDefault: (key: string, def: any) => {
     let v = localStorage.getItem(key)