diff -r b381da3a9b19 -r 54df904472b0 src/json.c
--- a/src/json.c	Thu Jan 09 21:19:52 2025 +0100
+++ b/src/json.c	Thu Jan 09 22:37:10 2025 +0100
@@ -988,7 +988,7 @@
 static const CxJsonWriter cx_json_writer_default = {
     false,
     true,
-    255,
+    6,
     false,
     4
 };
@@ -1001,7 +1001,7 @@
     return (CxJsonWriter) {
         true,
         true,
-        255,
+        6,
         use_spaces,
         4
     };
@@ -1050,7 +1050,7 @@
     size_t actual = 0, expected = 0;
 
     // small buffer for number to string conversions
-    char numbuf[32];
+    char numbuf[40];
 
     // recursively write the values
     switch (value->type) {
@@ -1160,12 +1160,71 @@
             break;
         }
         case CX_JSON_NUMBER: {
-            // TODO: locale bullshit
-            // TODO: formatting settings
-            snprintf(numbuf, 32, "%g", value->value.number);
-            size_t len = strlen(numbuf);
-            actual += wfunc(numbuf, 1, len, target);
-            expected += len;
+            int precision = settings->frac_max_digits;
+            // because of the way how %g is defined, we need to
+            // double the precision and truncate ourselves
+            precision = 1 + (precision > 15 ? 30 : 2 * precision);
+            snprintf(numbuf, 40, "%.*g", precision, value->value.number);
+            char *dot, *exp;
+            unsigned char max_digits;
+            // find the decimal separator and hope that it's one of . or ,
+            dot = strchr(numbuf, '.');
+            if (dot == NULL) {
+                dot = strchr(numbuf, ',');
+            }
+            if (dot == NULL) {
+                // no decimal separator found
+                // output everything until a possible exponent
+                max_digits = 30;
+                dot = numbuf;
+            } else {
+                // found a decimal separator
+                // output everything until the separator
+                // and set max digits to what the settings say
+                size_t len = dot - numbuf;
+                actual += wfunc(numbuf, 1, len, target);
+                expected += len;
+                max_digits = settings->frac_max_digits;
+                if (max_digits > 15) {
+                    max_digits = 15;
+                }
+                // locale independent separator
+                if (max_digits > 0) {
+                    actual += wfunc(".", 1, 1, target);
+                    expected++;
+                }
+                dot++;
+            }
+            // find the exponent
+            exp = strchr(dot, 'e');
+            if (exp == NULL) {
+                // no exponent - output the rest
+                if (max_digits > 0) {
+                    size_t len = strlen(dot);
+                    if (len > max_digits) {
+                        len = max_digits;
+                    }
+                    actual += wfunc(dot, 1, len, target);
+                    expected += len;
+                }
+            } else {
+                // exponent found - truncate the frac digits
+                // and then output the rest
+                if (max_digits > 0) {
+                    size_t len = exp - dot - 1;
+                    if (len > max_digits) {
+                        len = max_digits;
+                    }
+                    actual += wfunc(dot, 1, len, target);
+                    expected += len;
+                }
+                actual += wfunc("e", 1, 1, target);
+                expected++;
+                exp++;
+                size_t len = strlen(exp);
+                actual += wfunc(exp, 1, len, target);
+                expected += len;
+            }
             break;
         }
         case CX_JSON_INTEGER: {