diff --git a/Userland/seq.cpp b/Userland/seq.cpp
new file mode 100644
index 0000000000..cabc3d2ef1
--- /dev/null
+++ b/Userland/seq.cpp
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2020, Nico Weber <thakis@chromium.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StdLibExtras.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+double get_double(const char* name, const char* d_string, int* number_of_decimals)
+{
+    char* end;
+    double d = strtod(d_string, &end);
+    if (d == 0 && end == d_string) {
+        fprintf(stderr, "%s: invalid double vallue \"%s\"\n", name, d_string);
+        exit(1);
+    }
+    if (char* dot = strchr(d_string, '.'))
+        *number_of_decimals = strlen(dot + 1);
+    else
+        *number_of_decimals = 0;
+    return d;
+}
+
+int main(int argc, const char* argv[])
+{
+    if (pledge("stdio", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+    if (unveil(nullptr, nullptr) < 0) {
+        perror("unveil");
+        return 1;
+    }
+
+    double start = 1, step = 1, end = 1;
+    int number_of_start_decimals = 0, number_of_step_decimals = 0, number_of_end_decimals = 0;
+    switch (argc) {
+    case 2:
+        end = get_double(argv[0], argv[1], &number_of_end_decimals);
+        break;
+    case 3:
+        start = get_double(argv[0], argv[1], &number_of_start_decimals);
+        end = get_double(argv[0], argv[2], &number_of_end_decimals);
+        break;
+    case 4:
+        start = get_double(argv[0], argv[1], &number_of_start_decimals);
+        step = get_double(argv[0], argv[2], &number_of_step_decimals);
+        end = get_double(argv[0], argv[3], &number_of_end_decimals);
+        break;
+    default:
+        fprintf(stderr, "%s: unexpected number of arguments\n", argv[0]);
+        return 1;
+    }
+
+    if (step == 0) {
+        fprintf(stderr, "%s: increment must not be 0\n", argv[0]);
+        return 1;
+    }
+
+#if 0
+    // FIXME: Check for NaN once math.h has isnan().
+    if (isnan(start) || isnan(step) || isnan(end)) {
+        fprintf(stderr, "%s: start, step, and end must not be NaN\n", argv[0]);
+        return 1;
+    }
+#endif
+
+    int number_of_decimals = max(number_of_start_decimals, max(number_of_step_decimals, number_of_end_decimals));
+
+    int n = (end - start) / step;
+    double d = start;
+    for (int i = 0; i <= n; ++i) {
+        char buf[40];
+        sprintf(buf, "%f", d); // FIXME: Serenity's printf() doesn't seem to handle %f correctly: For `seq 1 0.1 2` this always prints "1.0" as `d` goes from 1.0 to 2.0.
+        if (char* dot = strchr(buf, '.')) {
+            if (number_of_decimals == 0)
+                *dot = '\0';
+            else if ((dot - buf) + 1 + number_of_decimals < (int)sizeof(buf))
+                dot[1 + number_of_decimals] = '\0';
+        }
+        printf("%s\n", buf);
+        d += step;
+    }
+}