diff --git a/.gitignore b/.gitignore
index 19095cd..730b8f8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@ build/
 *~
 *.swp
 *.log
+*.bak
 *.agda
 *.agdai
 /*.js
@@ -12,3 +13,8 @@ mkday.py
 tmp
 min.js.gz
 src/Revision.newt
+.calva
+.clj-kondo
+.joyride
+.lsp
+.vscode
diff --git a/Makefile b/Makefile
index 59e38c9..cb0d8c5 100644
--- a/Makefile
+++ b/Makefile
@@ -36,6 +36,7 @@ test: newt.js
 
 aoctest: newt.js
 	scripts/aoc
+	scripts/aoc25
 
 # Misc
 
diff --git a/aoc2025/Day1.newt.golden b/aoc2025/Day1.newt.golden
new file mode 100644
index 0000000..8be69c9
--- /dev/null
+++ b/aoc2025/Day1.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day1/eg.txt
+part1 3
+part2 6
+aoc2025/day1/input.txt
+part1 1100
+part2 6358
diff --git a/aoc2025/Day11.newt.golden b/aoc2025/Day11.newt.golden
new file mode 100644
index 0000000..e909439
--- /dev/null
+++ b/aoc2025/Day11.newt.golden
@@ -0,0 +1,11 @@
+aoc2025/day11/eg.txt
+part1 5
+svr missing {"tag":0}
+part2 0
+aoc2025/day11/eg2.txt
+you missing {"tag":0}
+part1 0
+part2 2
+aoc2025/day11/input.txt
+part1 636
+part2 509312913844956
diff --git a/aoc2025/Day12.newt.golden b/aoc2025/Day12.newt.golden
new file mode 100644
index 0000000..0eba3d6
--- /dev/null
+++ b/aoc2025/Day12.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day12/eg.txt
+[7, 7, 7, 7, 7, 7]
+3 rows, 0 easy, 3 maybe, 0 impossible
+aoc2025/day12/input.txt
+[7, 5, 7, 6, 7, 7]
+1000 rows, 479 easy, 0 maybe, 521 impossible
diff --git a/aoc2025/Day2.newt.golden b/aoc2025/Day2.newt.golden
new file mode 100644
index 0000000..0298356
--- /dev/null
+++ b/aoc2025/Day2.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day2/eg.txt
+part1 1227775554
+part2 4174379265
+aoc2025/day2/input.txt
+part1 18893502033
+part2 26202168557
diff --git a/aoc2025/Day3.newt.golden b/aoc2025/Day3.newt.golden
new file mode 100644
index 0000000..54c2554
--- /dev/null
+++ b/aoc2025/Day3.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day3/eg.txt
+part1 357
+part2 3121910778619
+aoc2025/day3/input.txt
+part1 17452
+part2 173300819005913
diff --git a/aoc2025/Day4.newt.golden b/aoc2025/Day4.newt.golden
new file mode 100644
index 0000000..6c892ee
--- /dev/null
+++ b/aoc2025/Day4.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day4/eg.txt
+part1 13
+part2 43
+aoc2025/day4/input.txt
+part1 1569
+part2 9280
diff --git a/aoc2025/Day5.newt.golden b/aoc2025/Day5.newt.golden
new file mode 100644
index 0000000..7f1ea50
--- /dev/null
+++ b/aoc2025/Day5.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day5/eg.txt
+part1 3
+part2 14
+aoc2025/day5/input.txt
+part1 862
+part2 357907198933892
diff --git a/aoc2025/Day6.newt.golden b/aoc2025/Day6.newt.golden
new file mode 100644
index 0000000..b967987
--- /dev/null
+++ b/aoc2025/Day6.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day6/eg.txt
+part1 4277556
+part2 3263827
+aoc2025/day6/input.txt
+part1 5346286649122
+part2 10389131401929
diff --git a/aoc2025/Day7.newt.golden b/aoc2025/Day7.newt.golden
new file mode 100644
index 0000000..4f15957
--- /dev/null
+++ b/aoc2025/Day7.newt.golden
@@ -0,0 +1,10 @@
+aoc2025/day7/eg.txt
+rows 15
+cols 14
+part1 21
+part2 40
+aoc2025/day7/input.txt
+rows 141
+cols 140
+part1 1587
+part2 5748679033029
diff --git a/aoc2025/Day8.newt.golden b/aoc2025/Day8.newt.golden
new file mode 100644
index 0000000..eafb2fa
--- /dev/null
+++ b/aoc2025/Day8.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day8/eg.txt
+part1 40
+part2 25272
+aoc2025/day8/input.txt
+part1 123234
+part2 9259958565
diff --git a/aoc2025/Day9.newt.golden b/aoc2025/Day9.newt.golden
new file mode 100644
index 0000000..ce70ea7
--- /dev/null
+++ b/aoc2025/Day9.newt.golden
@@ -0,0 +1,6 @@
+aoc2025/day9/eg.txt
+part1 6 50
+part2 24
+aoc2025/day9/input.txt
+part1 1222 4777816465
+part2 1410501884
diff --git a/aoc2025/Parser.newt b/aoc2025/Parser.newt
new file mode 100644
index 0000000..5f9cfe0
--- /dev/null
+++ b/aoc2025/Parser.newt
@@ -0,0 +1,75 @@
+module Parser
+
+import Prelude
+import Aoc
+
+Parser : U → U
+Parser a = List Char → Either String (a × List Char)
+
+instance Monad Parser where
+  pure a = \ cs => Right (a, cs)
+  bind ma mab = \ cs => ma cs >>= uncurry mab
+
+instance Alternative Parser where
+  pa <|> pb = \ cs => case pa cs of
+    Left msg => pb cs
+    res => res
+
+instance Functor Parser where
+  map f pa = \ cs => case pa cs of
+    Left msg => Left msg
+    Right (a, cs) => Right (f a, cs)
+
+instance Applicative Parser where
+  return a = pure a
+  pa <*> pb = pa >>= (\ f => map f pb)
+
+
+fail : ∀ a. String -> Parser a
+fail msg = \ cs => Left msg
+
+-- TODO, case builder isn't expanding Parser Unit to count lambdas
+eof : Parser Unit
+eof = \case
+  Nil => Right (MkUnit, Nil)
+  _ =>  Left "expected eof"
+
+satisfy : (Char → Bool) → Parser Char
+satisfy pred = \case
+  Nil => Left "unexpected EOF"
+  (c :: cs) => if pred c then Right (c, cs) else Left ("did not expect " ++ show c ++ " - " ++ pack cs)
+
+match : Char → Parser Char
+match d = satisfy (_==_ d)
+
+any : Parser Char
+any = satisfy (λ _ => True)
+
+some many : ∀ a. Parser a → Parser (List a)
+many p = some p <|> pure Nil
+some p = do
+  v <- p
+  vs <- many p
+  pure (v :: vs)
+
+string : String → Parser Unit
+string str = go (unpack str)
+  where
+    go : List Char → Parser Unit
+    go Nil = pure MkUnit
+    go (c :: cs) = match c >> go cs
+
+number : Parser Int
+number = stringToInt ∘ pack <$> some (satisfy isDigit)
+  -- do
+  -- digs <- some (satisfy isDigit)
+  -- pure $ stringToInt $ pack digs
+
+optional : ∀ a. Parser a → Parser (Maybe a)
+optional pa = Just <$> pa <|> pure Nothing
+
+ws : Parser Unit
+ws = many (match ' ') >> pure MkUnit
+
+token : String → Parser Unit
+token str = string str >> ws
diff --git a/scripts/aoc25 b/scripts/aoc25
new file mode 100755
index 0000000..42fe35e
--- /dev/null
+++ b/scripts/aoc25
@@ -0,0 +1,36 @@
+#!/bin/sh
+mkdir -p tmp
+echo "Test AoC 2025 solutions"
+NCC="node newt.js"
+total=0
+failed=0
+for fn in  aoc2025/Day*.newt; do
+  total=$((total + 1))
+  echo Test $fn
+  bn=$(basename $fn)
+  $NCC $fn -o out.js > tmp/${bn}.compile
+  if [ $? != "0" ]; then
+    echo Compile failed for $fn
+    failed=$((failed + 1))
+    continue
+  fi
+  # if there is a golden file, run the code and compare output
+  if [ -f ${fn}.golden ]; then
+    node out.js > tmp/${bn}.out
+    if [ $? != "0" ]; then
+      echo Run failed for $fn
+      failed=$((failed + 1))
+      continue
+    fi
+    if ! diff -q tmp/${bn}.out ${fn}.golden; then
+      echo "Output mismatch for $fn"
+      failed=$((failed + 1))
+      if [ $1 = "--fix" ]; then
+        cp tmp/${bn}.out ${fn}.golden
+      fi
+    fi
+  fi
+done
+
+echo "Total tests: $total"
+echo "Failed tests: $failed"