diff --git a/src/cli/index.test.ts b/src/cli/index.test.ts
index 4fc3459..4255bad 100644
--- a/src/cli/index.test.ts
+++ b/src/cli/index.test.ts
@@ -1,9 +1,20 @@
-import { describe, expect, it } from "bun:test";
-import { spawnSync } from "node:child_process";
+import { afterEach, describe, expect, it } from "bun:test";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
 import { join } from "node:path";
+import { spawnSync } from "node:child_process";
 import type { SystemSnapshot } from "../collectors/local.js";
 import { formatCompactStatus } from "./index.js";
 
+let configDir: string | undefined;
+
+afterEach(() => {
+  if (configDir) {
+    rmSync(configDir, { recursive: true, force: true });
+    configDir = undefined;
+  }
+});
+
 function makeSnapshot(overrides: Partial<SystemSnapshot> = {}): SystemSnapshot {
   return {
     machineId: "local",
@@ -55,6 +66,11 @@ function stripAnsi(value: string): string {
   return value.replace(/\u001B\[[0-?]*[ -/]*[@-~]/g, "");
 }
 
+function writeConfig(config: unknown): void {
+  configDir = mkdtempSync(join(tmpdir(), "monitor-cli-"));
+  writeFileSync(join(configDir, "config.json"), JSON.stringify(config));
+}
+
 describe("monitor status --compact", () => {
   it("formats a stable single-line summary using the root disk", () => {
     const output = stripAnsi(formatCompactStatus(makeSnapshot()));
@@ -82,3 +98,58 @@ describe("monitor status --compact", () => {
     expect(child.stdout).not.toContain("\u001B");
   });
 });
+
+describe("monitor compare", () => {
+  it("emits one JSON row per configured machine", () => {
+    writeConfig({
+      machines: [
+        { id: "local-a", label: "Local A", type: "local" },
+        { id: "local-b", label: "Local B", type: "local" },
+      ],
+    });
+
+    const result = spawnSync(
+      process.execPath,
+      ["run", "./bins/monitor.ts", "compare", "--json"],
+      {
+        cwd: process.cwd(),
+        env: { ...process.env, MONITOR_CONFIG_DIR: configDir },
+        encoding: "utf-8",
+        timeout: 30_000,
+      }
+    );
+
+    expect(result.status).toBe(0);
+    const rows = JSON.parse(result.stdout) as Array<Record<string, unknown>>;
+    expect(rows).toHaveLength(2);
+    expect(rows.map((row) => row.machineId)).toEqual(["local-a", "local-b"]);
+    for (const row of rows) {
+      expect(typeof row.cpuPercent).toBe("number");
+      expect(typeof row.memPercent).toBe("number");
+      expect(row.diskPercent === null || typeof row.diskPercent === "number").toBe(true);
+      expect(row.error).toBeNull();
+    }
+  });
+
+  it("resolves explicit machine aliases", () => {
+    writeConfig({
+      machines: [{ id: "local-a", label: "Local A", type: "local" }],
+      aliases: { prod: "local-a" },
+    });
+
+    const result = spawnSync(
+      process.execPath,
+      ["run", "./bins/monitor.ts", "compare", "prod", "--json"],
+      {
+        cwd: process.cwd(),
+        env: { ...process.env, MONITOR_CONFIG_DIR: configDir },
+        encoding: "utf-8",
+        timeout: 30_000,
+      }
+    );
+
+    expect(result.status).toBe(0);
+    const rows = JSON.parse(result.stdout) as Array<Record<string, unknown>>;
+    expect(rows.map((row) => row.machineId)).toEqual(["local-a"]);
+  });
+});
diff --git a/src/cli/index.ts b/src/cli/index.ts
index 9f4cf96..d619c39 100644
--- a/src/cli/index.ts
+++ b/src/cli/index.ts
@@ -75,6 +75,16 @@ type MachineListItem = {
   host?: string | null;
 };
 
+type MachineComparisonRow = {
+  machineId: string;
+  hostname: string | null;
+  cpuPercent: number | null;
+  memPercent: number | null;
+  diskPercent: number | null;
+  diskMount: string | null;
+  error: string | null;
+};
+
 // ── Unicode progress bar ───────────────────────────────────────────────────────
 
 function progressBar(pct: number, width = 20): string {
@@ -293,6 +303,49 @@ function printPageHint<T>(
   }
 }
 
+async function collectMachineComparison(machineId: string): Promise<MachineComparisonRow> {
+  try {
+    const result = await getCollectorForMachine(machineId).collect();
+    if (!result.ok) {
+      return {
+        machineId,
+        hostname: null,
+        cpuPercent: null,
+        memPercent: null,
+        diskPercent: null,
+        diskMount: null,
+        error: result.error,
+      };
+    }
+
+    const disk = result.snapshot.disks.reduce<(typeof result.snapshot.disks)[number] | null>(
+      (highest, candidate) =>
+        !highest || candidate.usagePercent > highest.usagePercent ? candidate : highest,
+      null
+    );
+
+    return {
+      machineId: result.snapshot.machineId,
+      hostname: result.snapshot.hostname,
+      cpuPercent: result.snapshot.cpu.usagePercent,
+      memPercent: result.snapshot.mem.usagePercent,
+      diskPercent: disk?.usagePercent ?? null,
+      diskMount: disk?.mount ?? null,
+      error: null,
+    };
+  } catch (error) {
+    return {
+      machineId,
+      hostname: null,
+      cpuPercent: null,
+      memPercent: null,
+      diskPercent: null,
+      diskMount: null,
+      error: error instanceof Error ? error.message : String(error),
+    };
+  }
+}
+
 async function renderInstalledApps(
   machineArg: string | undefined,
   opts: { all?: boolean; compare?: boolean; json?: boolean; limit?: number; cursor?: number; verbose?: boolean },
@@ -468,6 +521,50 @@ program
     console.log();
   });
 
+// ── monitor compare [machines...] ────────────────────────────────────────────
+
+program
+  .command("compare [machines...]")
+  .description("Compare CPU, memory, and disk usage across machines")
+  .option("-n, --limit <n>", "Number of machines to show", parseLimitOption, DEFAULT_LIST_LIMIT)
+  .option("--cursor <n>", "Zero-based row offset for the next page", parseCursorOption, 0)
+  .option("-j, --json", "Output raw JSON")
+  .action(async (machineArgs: string[], opts) => {
+    const machineIds = machineArgs.length > 0 ? machineArgs.map(resolveMachineId) : listKnownMachineIds();
+    const rows = await Promise.all(machineIds.map(collectMachineComparison));
+
+    if (opts.json) {
+      console.log(JSON.stringify(rows, null, 2));
+      return;
+    }
+
+    console.log();
+    console.log(
+      chalk.dim(
+        `  ${"MACHINE".padEnd(24)} ${"CPU".padStart(7)} ${"MEMORY".padStart(7)} ${"DISK".padStart(7)}  MOUNT`
+      )
+    );
+    const page = pageItems(rows, {
+      limit: opts.limit,
+      cursor: opts.cursor,
+      defaultLimit: DEFAULT_LIST_LIMIT,
+    });
+
+    for (const row of page.items) {
+      const machine = truncateText(row.machineId, 24).padEnd(24);
+      if (row.error) {
+        console.log(`  ${machine} ${chalk.red(row.error)}`);
+        continue;
+      }
+
+      console.log(
+        `  ${machine} ${formatPct(row.cpuPercent!)} ${formatPct(row.memPercent!)} ${row.diskPercent === null ? chalk.dim("    -  ") : formatPct(row.diskPercent)}  ${row.diskMount ?? "-"}`
+      );
+    }
+    printPageHint(page, "Use --limit, --cursor, or --json for more machines.");
+    console.log();
+  });
+
 // ── monitor health ────────────────────────────────────────────────────────────
 
 program