diff --git a/src/userland/sys/lsblk.c b/src/userland/sys/lsblk.c
new file mode 100644
index 0000000..d7a182e
--- /dev/null
+++ b/src/userland/sys/lsblk.c
@@ -0,0 +1,322 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <syscall.h>
+
+#define LSBLK_MAX_DISKS 32
+#define LSBLK_SECTOR_SIZE 512ULL
+#define LSBLK_KB 1024ULL
+#define LSBLK_MB (1024ULL * 1024ULL)
+#define LSBLK_GB (1024ULL * 1024ULL * 1024ULL)
+
+static int streq(const char *a, const char *b) {
+    return strcmp(a, b) == 0;
+}
+
+static int starts_with(const char *s, const char *prefix) {
+    while (*prefix) {
+        if (*s++ != *prefix++) return 0;
+    }
+    return 1;
+}
+
+static const char *device_name_arg(const char *arg) {
+    if (starts_with(arg, "/dev/")) return arg + 5;
+    return arg;
+}
+
+static void format_size(uint64_t bytes, char *out, size_t out_len, int compact) {
+    const char *sep = compact ? "" : " ";
+    uint64_t unit = 1;
+    const char *suffix = "B";
+
+    if (bytes >= LSBLK_GB) {
+        unit = LSBLK_GB;
+        suffix = "GB";
+    } else if (bytes >= LSBLK_MB) {
+        unit = LSBLK_MB;
+        suffix = "MB";
+    } else if (bytes >= LSBLK_KB) {
+        unit = LSBLK_KB;
+        suffix = "KB";
+    }
+
+    if (unit == 1) {
+        snprintf(out, out_len, "%llu%s%s", (unsigned long long)bytes, sep, suffix);
+        return;
+    }
+
+    uint64_t whole = bytes / unit;
+    uint64_t rem = bytes % unit;
+    uint64_t tenth = (rem * 10ULL + unit / 2ULL) / unit;
+
+    if (tenth >= 10ULL) {
+        whole++;
+        tenth = 0;
+    }
+
+    if (tenth == 0) {
+        snprintf(out, out_len, "%llu%s%s", (unsigned long long)whole, sep, suffix);
+    } else {
+        snprintf(out, out_len, "%llu.%llu%s%s", (unsigned long long)whole, (unsigned long long)tenth, sep, suffix);
+    }
+}
+
+static uint64_t disk_size_bytes(const disk_info_t *d) {
+    return (uint64_t)d->total_sectors * LSBLK_SECTOR_SIZE;
+}
+
+static int is_child_partition(const disk_info_t *disk, const disk_info_t *part) {
+    size_t len;
+
+    if (disk->is_partition || !part->is_partition) return 0;
+
+    len = strlen(disk->devname);
+    if (strncmp(part->devname, disk->devname, len) != 0) return 0;
+
+    return part->devname[len] >= '0' && part->devname[len] <= '9';
+}
+
+static int child_count(const disk_info_t *disk, disk_info_t *items, int count) {
+    int children = 0;
+
+    for (int i = 0; i < count; i++) {
+        if (is_child_partition(disk, &items[i])) children++;
+    }
+
+    return children;
+}
+
+static void print_tree_device(const disk_info_t *d, const char *branch) {
+    char size[24];
+    const char *type = d->is_partition ? "part" : "disk";
+
+    format_size(disk_size_bytes(d), size, sizeof(size), 0);
+
+    if (d->is_partition) {
+        if (branch[0]) printf("%s %-8s %8s  %s", branch, d->devname, size, type);
+        else printf("/dev/%-8s %8s  %s", d->devname, size, type);
+        if (d->is_fat32) printf("  FAT32");
+        if (d->label[0]) printf("  %s", d->label);
+        if (d->is_esp) printf("  [ESP]");
+        printf("\n");
+    } else {
+        printf("/dev/%-8s %8s  %s\n", d->devname, size, type);
+    }
+}
+
+static void print_tree_disk(const disk_info_t *disk, disk_info_t *items, int count) {
+    int children = child_count(disk, items, count);
+    int seen = 0;
+
+    print_tree_device(disk, "");
+
+    for (int i = 0; i < count; i++) {
+        if (!is_child_partition(disk, &items[i])) continue;
+        seen++;
+        print_tree_device(&items[i], seen == children ? "└─" : "├─");
+    }
+}
+
+static void print_raw_device(const disk_info_t *d) {
+    char size[24];
+
+    format_size(disk_size_bytes(d), size, sizeof(size), 1);
+    printf("/dev/%s %s %s", d->devname, size, d->is_partition ? "part" : "disk");
+
+    if (d->is_partition) {
+        if (d->is_fat32) printf(" FAT32");
+        if (d->label[0]) printf(" %s", d->label);
+        if (d->is_esp) printf(" ESP");
+    }
+
+    printf("\n");
+}
+
+static void print_raw_disk(const disk_info_t *disk, disk_info_t *items, int count) {
+    print_raw_device(disk);
+
+    for (int i = 0; i < count; i++) {
+        if (is_child_partition(disk, &items[i])) print_raw_device(&items[i]);
+    }
+}
+
+static void json_string(const char *s) {
+    putchar('"');
+
+    while (*s) {
+        if (*s == '"' || *s == '\\') {
+            putchar('\\');
+            putchar(*s);
+        } else if (*s == '\n') {
+            printf("\\n");
+        } else {
+            putchar(*s);
+        }
+        s++;
+    }
+
+    putchar('"');
+}
+
+static void json_device_fields(const disk_info_t *d) {
+    char size[24];
+    char name[24];
+
+    format_size(disk_size_bytes(d), size, sizeof(size), 0);
+    snprintf(name, sizeof(name), "/dev/%s", d->devname);
+
+    printf("\"name\":");
+    json_string(name);
+    printf(",\"size\":");
+    json_string(size);
+    printf(",\"type\":");
+    json_string(d->is_partition ? "part" : "disk");
+    printf(",\"fstype\":");
+    json_string(d->is_fat32 ? "FAT32" : "");
+    printf(",\"label\":");
+    json_string(d->label);
+    printf(",\"flags\":[");
+    if (d->is_esp) json_string("ESP");
+    printf("]");
+}
+
+static void print_json_partition(const disk_info_t *d) {
+    printf("{");
+    json_device_fields(d);
+    printf("}");
+}
+
+static void print_json_disk(const disk_info_t *disk, disk_info_t *items, int count) {
+    int seen = 0;
+
+    printf("{");
+    json_device_fields(disk);
+    printf(",\"children\":[");
+
+    for (int i = 0; i < count; i++) {
+        if (!is_child_partition(disk, &items[i])) continue;
+        if (seen > 0) printf(",");
+        print_json_partition(&items[i]);
+        seen++;
+    }
+
+    printf("]}");
+}
+
+static int load_disks(disk_info_t *items, int max) {
+    int total = sys_disk_get_count();
+    int count = 0;
+
+    for (int i = 0; i < total && count < max; i++) {
+        if (sys_disk_get_info(i, &items[count]) == 0) count++;
+    }
+
+    return count;
+}
+
+static void usage(void) {
+    printf("Usage: lsblk [-r] [--json] [/dev/DEVICE]\n");
+}
+
+int main(int argc, char **argv) {
+    disk_info_t items[LSBLK_MAX_DISKS];
+    const char *filter = NULL;
+    int raw = 0;
+    int json = 0;
+    int count;
+    int printed = 0;
+
+    for (int i = 1; i < argc; i++) {
+        if (streq(argv[i], "-r")) {
+            raw = 1;
+        } else if (streq(argv[i], "--json")) {
+            json = 1;
+        } else if (streq(argv[i], "-h") || streq(argv[i], "--help")) {
+            usage();
+            return 0;
+        } else if (argv[i][0] == '-') {
+            printf("lsblk: unknown option: %s\n", argv[i]);
+            usage();
+            return 1;
+        } else if (!filter) {
+            filter = device_name_arg(argv[i]);
+        } else {
+            printf("lsblk: only one device filter is supported\n");
+            return 1;
+        }
+    }
+
+    if (raw && json) {
+        printf("lsblk: -r and --json cannot be used together\n");
+        return 1;
+    }
+
+    count = load_disks(items, LSBLK_MAX_DISKS);
+
+    if (json) {
+        printf("{\"devices\":[");
+
+        for (int i = 0; i < count; i++) {
+            if (items[i].is_partition) continue;
+            if (filter && !streq(items[i].devname, filter)) continue;
+            if (printed > 0) printf(",");
+            print_json_disk(&items[i], items, count);
+            printed++;
+        }
+
+        if (filter && printed == 0) {
+            for (int i = 0; i < count; i++) {
+                if (!items[i].is_partition || !streq(items[i].devname, filter)) continue;
+                print_json_partition(&items[i]);
+                printed++;
+                break;
+            }
+        }
+
+        printf("]}\n");
+    } else if (raw) {
+        for (int i = 0; i < count; i++) {
+            if (items[i].is_partition) continue;
+            if (filter && !streq(items[i].devname, filter)) continue;
+            print_raw_disk(&items[i], items, count);
+            printed++;
+        }
+
+        if (filter && printed == 0) {
+            for (int i = 0; i < count; i++) {
+                if (!items[i].is_partition || !streq(items[i].devname, filter)) continue;
+                print_raw_device(&items[i]);
+                printed++;
+                break;
+            }
+        }
+    } else {
+        for (int i = 0; i < count; i++) {
+            if (items[i].is_partition) continue;
+            if (filter && !streq(items[i].devname, filter)) continue;
+            print_tree_disk(&items[i], items, count);
+            printed++;
+        }
+
+        if (filter && printed == 0) {
+            for (int i = 0; i < count; i++) {
+                if (!items[i].is_partition || !streq(items[i].devname, filter)) continue;
+                print_tree_device(&items[i], "");
+                printed++;
+                break;
+            }
+        }
+    }
+
+    if (printed == 0 && !json) {
+        if (filter) printf("lsblk: /dev/%s not found\n", filter);
+        else printf("lsblk: no block devices found\n");
+        return 1;
+    }
+
+    if (printed == 0 && filter) return 1;
+    return 0;
+}