diff --git a/services/api/server.mjs b/services/api/server.mjs
index 8c63706..65c23e3 100644
--- a/services/api/server.mjs
+++ b/services/api/server.mjs
@@ -380,7 +380,7 @@ function clampSeriesLimit(value, fallback) {
 }
 
 function parseTimeframeToSeconds(tf) {
-  const v = String(tf || '').trim().toLowerCase();
+  const v = normalizeChartTimeframe(tf);
   if (!v) return 60;
   const m = v.match(/^(\d+)(s|m|h|d)$/);
   if (!m) throw new Error(`invalid_tf`);
@@ -391,6 +391,40 @@ function parseTimeframeToSeconds(tf) {
   return num * mult;
 }
 
+const SUPPORTED_CHART_TIMEFRAMES = new Set([
+  '1s',
+  '5s',
+  '15s',
+  '30s',
+  '1m',
+  '5m',
+  '15m',
+  '30m',
+  '1h',
+  '4h',
+  '8h',
+  '12h',
+  '1d',
+]);
+
+function normalizeChartTimeframe(tf) {
+  const raw = String(tf || '').trim();
+  if (!raw) return '1m';
+
+  const aliased =
+    raw === '1D' || raw === '24h' || raw === '24H'
+      ? '1d'
+      : raw === '1H'
+        ? '1h'
+        : raw.toLowerCase();
+
+  if (!SUPPORTED_CHART_TIMEFRAMES.has(aliased)) {
+    throw new Error('invalid_tf');
+  }
+
+  return aliased;
+}
+
 function isTruthy(value) {
   if (typeof value === 'boolean') return value;
   const v = String(value ?? '').trim().toLowerCase();