diff --git a/app/crawler/main.sh b/app/crawler/main.sh
new file mode 100644
index 0000000..a565844
--- /dev/null
+++ b/app/crawler/main.sh
@@ -0,0 +1,104 @@
+#! /bin/bash
+
+main() {
+   config
+   for id in $(ids); do
+      if should_crawl "$id"; then
+         crawl "$id"
+      fi
+      rewrite "$id"
+   done
+}
+
+config() {
+   set -o pipefail
+   set -e
+   export CACHE=$(mktemp -d)
+   export CRAWL_INTERVAL=$((60*5))
+   export NOTEA_ADDR="${NOTEA_ADDR:-"http://localhost:3000"}"
+}
+
+log() {
+   echo "$(date)> $*" >&2
+}
+
+ids() {
+   notea ids
+}
+
+should_crawl() {
+   local f="$CACHE/crawled_$1"
+   if [ ! -f "$f" ]; then
+      return 0
+   fi
+   local last_crawled=$(date -r "$f" +%s)
+   local now=$(date +%s)
+   if ((now-last_crawled < CRAWL_INTERVAL)); then
+      return 0
+   fi
+   return 1
+}
+
+crawl() {
+   local id="$1"
+   local json="$(notea get "$id")"
+   local content="$(echo "$json" | jq -r .content)"
+   if ! is_crawlable "$content"; then
+      return 0
+   fi
+   log not impl crawl
+   return 1
+}
+
+is_crawlable() {
+   # https://unix.stackexchange.com/questions/181254/how-to-use-grep-and-cut-in-script-to-obtain-website-urls-from-an-html-file
+   local url_pattern="(http|https)://[a-zA-Z0-9./?=_%:-]*"
+   if echo "$*" | tr -d '\n' | grep -E "^[ ]*$url_pattern[ ]*$"; then
+      return 0
+   fi
+   if echo "$*" | head -n 1 | grep -E "^[ ]*_source_: $url_pattern[ ]*$"; then
+      return 0
+   fi
+   return 1
+}
+
+rewrite() {
+   log not impl rewrite
+   return 1
+}
+
+notea() (
+   ncurl() {
+      curl -sS "$@"
+   }
+
+   ids() {
+      ncurl $NOTEA_ADDR/api/tree \
+         | jq -r '.items \
+         | to_entries[].value.id' \
+         | grep -v '^root$'
+   }
+
+   get() {
+      local cached="$CACHE/cache_$1"
+      if [ -f "$cached" ] && cat "$cached" | grep .; then
+         return 0
+      fi
+      _get "$@" | tee "$cached"
+   }
+
+   _get() {
+      ncurl $NOTEA_ADDR/api/notes/$1
+   }
+
+   "$@"
+)
+
+crawler() (
+   should() {
+   }
+)
+
+if [ "$0" == "$BASH_SOURCE" ]; then
+   main "$@"
+fi
diff --git a/app/ui/run.sh b/app/ui/run.sh
new file mode 120000
index 0000000..34ad5ff
--- /dev/null
+++ b/app/ui/run.sh
@@ -0,0 +1 @@
+../../spike/review/run.sh
\ No newline at end of file