diff --git a/devforms.cabal b/devforms.cabal
--- a/devforms.cabal
+++ b/devforms.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               devforms
-version:            0.1.1.0
+version:            0.1.2.0
 synopsis:           A builder DSL for HTML survey forms with built-in server and storage
 description:
     devforms is a Haskell library for building HTML survey forms using a
diff --git a/examples/Example.hs b/examples/Example.hs
--- a/examples/Example.hs
+++ b/examples/Example.hs
@@ -26,4 +26,4 @@
             setUpperBoundInclusive 15
         questionLikert "This form works well"
         questionTime "Select a time"
-        questionText "Any special requests?"
+        questionFreeText "Any special requests?"
diff --git a/src/DevForms.hs b/src/DevForms.hs
--- a/src/DevForms.hs
+++ b/src/DevForms.hs
@@ -24,11 +24,11 @@
             setUpperBoundInclusive 10
 @
 -}
-module DevForms (ServerBuilder, FormBuilder, QuestionBuilder, devFormServer, form, questionCheckbox, questionLikert, questionChoice, questionDate, questionTime, questionInteger, setLowerBoundInclusive, setUpperBoundInclusive, questionText) where
+module DevForms (ServerBuilder, FormBuilder, QuestionBuilder, devFormServer, form, questionCheckbox, questionLikert, questionChoice, questionDate, questionTime, questionInteger, setLowerBoundInclusive, setUpperBoundInclusive, questionFreeText) where
 
 import Control.Monad.Writer
 import Form (Form (..), FormBuilder)
-import Question (Question (..), QuestionBuilder, QuestionOptions (..))
+import Question (Question (..), QuestionBuilder, QuestionOptions (..), QuestionType (..))
 import Server (Server (..), ServerBuilder, runServer)
 
 {- | Start the devforms web server on the given port.
@@ -71,14 +71,14 @@
 respondent can tick or leave unticked.
 -}
 questionCheckbox :: Text -> FormBuilder ()
-questionCheckbox =
-    addQuestion . QuestionCheckbox
+questionCheckbox questionText =
+    addQuestion $ Question questionText QuestionCheckbox
 
 {- | Add a Likert-scale question. Renders as a 5-point agreement scale
 (Strongly disagree … Strongly agree) plus a \"Cannot say\" option.
 -}
 questionLikert :: Text -> FormBuilder ()
-questionLikert = addQuestion . QuestionLikert
+questionLikert questionText = addQuestion $ Question questionText QuestionLikert
 
 {- | Add a multiple-choice question. Renders as a group of radio buttons — the
 respondent must select exactly one of the provided options.
@@ -87,19 +87,19 @@
 -}
 questionChoice :: Text -> [Text] -> FormBuilder ()
 questionChoice title qOptions =
-    addQuestion $ QuestionChoice title qOptions
+    addQuestion $ Question title (QuestionChoice qOptions)
 
 {- | Add a date-picker question. Renders as an HTML date input and stores the
 answer in @YYYY-MM-DD@ format.
 -}
 questionDate :: Text -> FormBuilder ()
-questionDate = addQuestion . QuestionDate
+questionDate questionText = addQuestion $ Question questionText QuestionDate
 
 {- | Add a time-picker question. Renders as an HTML time input and stores the
 answer in @HH:MM@ format.
 -}
 questionTime :: Text -> FormBuilder ()
-questionTime = addQuestion . QuestionTime
+questionTime questionText = addQuestion $ Question questionText QuestionTime
 
 {- | Add an integer input question. The second argument is a 'QuestionBuilder'
 block where you can optionally configure bounds using
@@ -117,7 +117,7 @@
 questionInteger :: Text -> QuestionBuilder () -> FormBuilder ()
 questionInteger title questionBuilder = do
     let questionOptions = appEndo (execWriter questionBuilder) $ QuestionOptions{lowerBoundInclusive = Nothing, upperBoundInclusive = Nothing}
-    addQuestion $ QuestionInteger title questionOptions
+    addQuestion $ Question title (QuestionInteger questionOptions)
 
 -- | Set the minimum allowed value (inclusive) for a 'questionInteger'.
 setLowerBoundInclusive :: Integer -> QuestionBuilder ()
@@ -127,5 +127,5 @@
 setUpperBoundInclusive :: Integer -> QuestionBuilder ()
 setUpperBoundInclusive bound = tell $ Endo $ \questionOptions -> questionOptions{upperBoundInclusive = Just bound}
 
-questionText :: Text -> FormBuilder ()
-questionText = addQuestion . QuestionText
+questionFreeText :: Text -> FormBuilder ()
+questionFreeText questionText = addQuestion $ Question questionText QuestionFreeText
diff --git a/src/Form.hs b/src/Form.hs
--- a/src/Form.hs
+++ b/src/Form.hs
@@ -14,9 +14,13 @@
 renderForm form@Form{title, questions} = do
     main_ $ do
         h2_ $ toHtml title
-        form_ [hxPost_ $ getSubmitUrl form, script_ "on keydown[key is 'Enter'] from <input/> halt"] $ do
-            forM_ (reverse questions) renderQuestion
-            input_ [type_ "submit"]
+        validationEnhancer_ $
+            form_ [hxPost_ $ getSubmitUrl form, script_ "on keydown[key is 'Enter'] from <input/> halt"] $ do
+                forM_ (reverse questions) renderQuestion
+                input_ [type_ "submit"]
+
+validationEnhancer_ :: Html () -> Html ()
+validationEnhancer_ = term "validation-enhancer"
 
 getFormUrl :: (IsString a) => Form -> a
 getFormUrl Form{formId} = fromString $ "/" <> toString formId
diff --git a/src/Question.hs b/src/Question.hs
--- a/src/Question.hs
+++ b/src/Question.hs
@@ -1,18 +1,25 @@
 {-# LANGUAGE QuasiQuotes #-}
 
-module Question (Question (..), QuestionOptions (..), QuestionBuilder, renderQuestion, parseAnswers) where
+module Question (Question (..), QuestionType (..), QuestionOptions (..), QuestionBuilder, renderQuestion, parseAnswers) where
 
 import Control.Monad.Writer
 import Data.Aeson qualified as JSON
 import Data.Aeson.Key qualified as Key
+import Data.Char (isAlphaNum)
 import Data.String.Interpolate
 import Data.Text qualified as Text
 import Lucid
 import ParsedInteger
 import Relude.Extra.Map as Map
 
-data Question = QuestionCheckbox Text | QuestionLikert Text | QuestionChoice Text [Text] | QuestionDate Text | QuestionInteger Text QuestionOptions | QuestionTime Text | QuestionText Text deriving (Show)
+data Question = Question
+    { questionText :: Text
+    , questionType :: QuestionType
+    }
+    deriving (Show)
 
+data QuestionType = QuestionCheckbox | QuestionLikert | QuestionChoice [Text] | QuestionDate | QuestionInteger QuestionOptions | QuestionTime | QuestionFreeText deriving (Show)
+
 -- | A builder monad for configuring question options (e.g. bounds for integer questions).
 type QuestionBuilder = Writer (Endo QuestionOptions)
 
@@ -26,24 +33,50 @@
 runJust _ (Just x) f = f x
 runJust defaultValue Nothing _ = defaultValue
 
+questionId :: Text -> Text
+questionId questionText = Text.intercalate "-" (Text.words slug)
+  where
+    slug = Text.toLower $ Text.map (\c -> if isAlphaNum c || c == ' ' then c else ' ') questionText
+
+{- | Generate a unique validation tooltip ID from question text.
+E.g. "How old are you?" -> "err-how-old-are-you"
+-}
+validationId :: Text -> Text
+validationId questionText = "err-" <> questionId questionText
+
 renderQuestion :: Question -> Html ()
-renderQuestion question = do
-    section_ $ do
-        case question of
-            QuestionCheckbox questionText -> do
-                h3_ $ toHtml questionText
-                input_ [type_ "checkbox", name_ questionText]
-            QuestionChoice questionText choices -> do
-                h3_ $ toHtml questionText
+renderQuestion Question{questionText, questionType} = do
+    div_ [class_ "input"] $ do
+        let qId = questionId questionText
+        let errId = validationId questionText
+        case questionType of
+            QuestionChoice _ -> mempty
+            QuestionLikert -> mempty
+            _ -> label_ [Lucid.for_ qId] $ toHtml questionText
+        case questionType of
+            QuestionCheckbox -> do
+                input_ [id_ qId, type_ "checkbox", name_ questionText]
+            QuestionChoice choices -> do
+                let radioScript =
+                        [__i|
+                      on change
+                        set radios to <input[name='#{qId}']/> in closest <fieldset/>
+                        for radio in radios
+                          remove .invalid from radio
+                          add .valid to radio
+                        end
+                      end
+                    |] ::
+                            Text
                 fieldset_ $ do
+                    legend_ $ toHtml questionText
                     forM_ choices $ \c -> do
                         div_ $ do
-                            input_ [type_ "radio", name_ questionText, value_ c, required_ ""]
-                            label_ [Lucid.for_ questionText] $ toHtml c
-            QuestionDate questionText -> do
-                h3_ $ toHtml questionText
-                input_ [type_ "date", name_ questionText, required_ ""]
-            QuestionInteger questionText (QuestionOptions{lowerBoundInclusive, upperBoundInclusive}) -> do
+                            input_ [id_ (qId <> c), type_ "radio", name_ qId, value_ c, required_ "", ariaErrormessage_ errId, script_ radioScript]
+                            label_ [Lucid.for_ (qId <> c)] $ toHtml c
+            QuestionDate -> do
+                input_ [type_ "date", name_ questionText, required_ "", ariaErrormessage_ errId]
+            QuestionInteger (QuestionOptions{lowerBoundInclusive, upperBoundInclusive}) -> do
                 let validationScriptParts =
                         [ [__i|
                           on input
@@ -51,20 +84,20 @@
                           end
                         |]
                         , runJust
-                                ""
-                                lowerBoundInclusive
-                                ( \lb ->
-                                    [__i|
+                            ""
+                            lowerBoundInclusive
+                            ( \lb ->
+                                [__i|
                             on input
                               if my.value < #{lb} then set my.value to #{lb}
                             end
                             |]
-                                )
+                            )
                         , runJust
-                                ""
-                                upperBoundInclusive
-                                ( \ub ->
-                                    [__i|
+                            ""
+                            upperBoundInclusive
+                            ( \ub ->
+                                [__i|
 
                             on input
                               if my.value > #{ub} then
@@ -76,11 +109,10 @@
                                 set my.value to newValue
                             end
                             |]
-                                )
+                            )
                         ]
                 let validationScript = Text.intercalate "\n" validationScriptParts
 
-                h3_ $ toHtml questionText
                 input_ $
                     catMaybes
                         [ Just $ type_ "number"
@@ -89,10 +121,23 @@
                         , Just $ pattern_ "[0-9]+"
                         , Just $ required_ ""
                         , Just $ script_ validationScript
+                        , Just $ ariaErrormessage_ errId
+                        , Just $ id_ "integer"
                         , fmap (min_ . show) lowerBoundInclusive
                         , fmap (max_ . show) upperBoundInclusive
                         ]
-            QuestionLikert questionText -> do
+            QuestionLikert -> do
+                let radioScript =
+                        [__i|
+                      on change
+                        set radios to <input[name='#{qId}']/> in closest <fieldset/>
+                        for radio in radios
+                          remove .invalid from radio
+                          add .valid to radio
+                        end
+                      end
+                    |] ::
+                            Text
                 let choices =
                         [ "Strongly disagree" :: Text
                         , "Somewhat disagree"
@@ -100,41 +145,44 @@
                         , "Somewhat agree"
                         , "Strongly agree"
                         ]
-                h3_ $ toHtml questionText
-                forM_ choices $ \c -> do
+                fieldset_ $ do
+                    legend_ $ toHtml questionText
+                    forM_ choices $ \c -> do
+                        div_ $ do
+                            input_ [id_ (qId <> c), type_ "radio", name_ qId, value_ c, required_ "", ariaErrormessage_ errId, script_ radioScript]
+                            label_ [Lucid.for_ (qId <> c)] $ toHtml c
                     div_ $ do
-                        input_ [type_ "radio", name_ questionText, value_ c, required_ ""]
-                        toHtml c
-                div_ $ do
-                    input_ [type_ "radio", name_ questionText, value_ "Cannot say", required_ ""]
-                    "Cannot say"
-            QuestionTime questionText -> do
-                h3_ $ toHtml questionText
-                input_ [type_ "time", name_ questionText, required_ ""]
-            QuestionText questionText -> do
-                h3_ $ toHtml questionText
-                textarea_ [name_ questionText, required_ ""] ""
+                        input_ [id_ (qId <> "cannot-say"), type_ "radio", name_ qId, value_ "Cannot say", required_ "", script_ radioScript]
+                        label_ [Lucid.for_ (qId <> "cannot-say")] $ "Cannot say"
+            QuestionTime -> do
+                input_ [type_ "time", name_ questionText, required_ "", ariaErrormessage_ errId]
+            QuestionFreeText -> do
+                textarea_ [name_ questionText, required_ "", ariaErrormessage_ errId] ""
+        div_ [id_ errId, class_ "validation-message"] mempty
 
+ariaErrormessage_ :: Text -> Attributes
+ariaErrormessage_ = term "aria-errormessage"
+
 parseAnswers :: [Question] -> Map Text Text -> Either Text [(JSON.Key, JSON.Value)]
 parseAnswers questions params = mapM (`parseAnswer` params) questions
 
 parseAnswer :: Question -> Map Text Text -> Either Text (JSON.Key, JSON.Value)
-parseAnswer question params = case question of
-    QuestionCheckbox questionText ->
+parseAnswer Question{questionText, questionType} params = case questionType of
+    QuestionCheckbox ->
         let value = JSON.Bool $ isJust $ Map.lookup questionText params
          in Right (Key.fromText questionText, value)
-    QuestionInteger questionText QuestionOptions{lowerBoundInclusive, upperBoundInclusive} -> do
+    QuestionInteger QuestionOptions{lowerBoundInclusive, upperBoundInclusive} -> do
         answerRaw <- maybeToRight ("Missing required field: " <> questionText) $ Map.lookup questionText params
         n <- maybeToRight ("Invalid integer for: " <> questionText) (readMaybe (toString answerRaw) :: Maybe Integer)
         boundsCheckedInt <- parseWithBounds lowerBoundInclusive upperBoundInclusive n
         pure (Key.fromText questionText, JSON.toJSON (parsedToInteger boundsCheckedInt))
-    QuestionChoice questionText choices ->
+    QuestionChoice choices ->
         case Map.lookup questionText params of
             Nothing -> Left $ "Missing required field: " <> questionText
             Just raw
                 | raw `elem` choices -> Right (Key.fromText questionText, JSON.toJSON raw)
                 | otherwise -> Left $ "Invalid choice for: " <> questionText <> ". Got: " <> raw
-    QuestionLikert questionText ->
+    QuestionLikert ->
         let likertOptions =
                 [ "Strongly disagree"
                 , "Somewhat disagree"
@@ -148,19 +196,19 @@
                 Just raw
                     | raw `elem` likertOptions -> Right (Key.fromText questionText, JSON.toJSON raw)
                     | otherwise -> Left $ "Invalid Likert option for: " <> questionText <> ". Got: " <> raw
-    QuestionDate questionText ->
+    QuestionDate ->
         case lookup questionText params of
             Nothing -> Left $ "Missing required field: " <> questionText
             Just raw
                 | isValidDate raw -> Right (Key.fromText questionText, JSON.toJSON raw)
                 | otherwise -> Left $ "Invalid date format for: " <> questionText <> ". Expected YYYY-MM-DD"
-    QuestionTime questionText ->
+    QuestionTime ->
         case lookup questionText params of
             Nothing -> Left $ "Missing required field: " <> questionText
             Just raw
                 | isValidTime raw -> Right (Key.fromText questionText, JSON.toJSON raw)
                 | otherwise -> Left $ "Invalid time format for: " <> questionText <> ". Expected HH:MM"
-    QuestionText questionText ->
+    QuestionFreeText ->
         case lookup questionText params of
             Nothing -> Left $ "Missing required field: " <> questionText
             Just raw
diff --git a/src/Server.hs b/src/Server.hs
--- a/src/Server.hs
+++ b/src/Server.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
 {-# LANGUAGE TemplateHaskell #-}
 
 module Server (Server (..), ServerBuilder, runServer) where
@@ -8,6 +9,7 @@
 import Data.Aeson qualified as JSON
 import Data.FileEmbed (embedDir)
 import Data.Map qualified as Map
+import Data.String.Interpolate
 import Data.Time (UTCTime, getCurrentTime)
 import Form (Form (..), getFormUrl, getSubmitUrl, renderForm)
 import Lucid
@@ -34,6 +36,8 @@
             asset <- Scotty.pathParam "asset"
             when (takeExtension asset == ".svg") $ do
                 Scotty.addHeader "Content-Type" "image/svg+xml"
+            when (takeExtension asset == ".js") $ do
+                Scotty.addHeader "Content-Type" "application/javascript"
             case Map.lookup asset staticFiles of
                 Just content -> Scotty.raw $ toLazy content
                 Nothing -> Scotty.throw $ Scotty.QueryParameterNotFound $ toText asset
@@ -89,9 +93,43 @@
                 ( do
                     script_ [src_ "static/htmx.min.js"] ("" :: String)
                     script_ [src_ "static/_hyperscript.min.js"] ("" :: String)
+                    script_ [type_ "module", src_ "static/validation-enhancer.min.js"] ("" :: String)
                     link_ [rel_ "stylesheet", href_ "static/pico.classless.green.min.css"]
                     link_ [rel_ "stylesheet", href_ "https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css"]
+                    style_
+                        [__i|
+                      .valid {
+                        border-color: \#2e7d32;
+                      }
+
+                      .invalid {
+                        border-color: \#c62828;
+                      }
+
+                      .input {
+                        margin-bottom: 1.25rem;
+                      }
+
+                      .input input, .input fieldset {
+                        margin-bottom: 0rem;
+                      }
+
+                      .validation-message {
+                        font-size: 0.85rem;
+                        color: \#c62828;
+                        min-height: 1.25rem;
+                        margin-top: 0.2rem;
+                      }
+
+                      .input>label, fieldset>legend {
+                        display: block;
+                        font-weight: 600;
+                        margin-bottom: 0.25rem;
+                      }
+
+                    |]
                 )
+
             body_
                 ( do
                     main_