kosa8 vs Vercel Sandbox

01The short verdict

Choose Vercel Sandbox if

• you deploy on Vercel already and want sandboxes in the same account and bill [1];
• you want 19 managed regions with failover and no hosts to run [3];
• you want to change egress rules on a running sandbox, or forward requests to your own proxy [5];
• your agents wait on models a lot: Active CPU billing does not count I/O wait [10].

Choose kosa8 if

• code must stay on your machine, your servers or an air-gapped site [13];
• you need to save memory and running processes, not only files, and rewind to that point [15];
• you want live copies of a running sandbox to try several approaches at once [14];
• you want a hash-chained audit log of sandbox actions on every plan [19].

02Vercel Sandbox and kosa8, feature by feature

Bracketed numbers point to the sources. "Not documented" means the vendor's own pages did not say on 2026-11-14; it does not mean the feature is missing.

03Where Vercel Sandbox is stronger

• Regions and scale. 19 regions with failover [3], and up to 10,000 concurrent sandboxes on Pro [10]. kosa8 Cloud has two regions and 20 sandboxes per organization by default [15].
• A flexible firewall on Cloud. Vercel's egress policy takes domains and CIDRs, changes without a restart, and brokers credentials [5]. kosa8 enforces allow-lists locally, but kosa8 Cloud has no egress setting yet [17].
• Billing for waiting agents. Active CPU excludes I/O wait such as model calls [10].
• Compliance and ecosystem. SOC 2 Type II infrastructure [6] and the rest of the Vercel platform; kosa8 has no SOC 2 report yet [21].

04Where kosa8 is different

• Memory survives. kosa8 checkpoints save memory, processes and disk; Vercel snapshots save the filesystem and stop the sandbox [4] [14].
• A true live fork. kosa8 fork copies a running sandbox as it is now [14].
• Off-cloud options. Your computer, your servers or air-gapped [13].
• Organization freeze. One call on kosa8 Cloud sleeps every sandbox and can suspend every key [17].

05Moving from Vercel Sandbox to kosa8

Vercel's quickstart creates a sandbox and runs a command with arguments [11]. In kosa8 the command and its arguments go in one list.

Vercel Sandbox, from its quickstart:

import { Sandbox } from '@vercel/sandbox';

async function main() {
  const sandbox = await Sandbox.create();

  const result = await sandbox.runCommand('echo', ['Hello from Vercel Sandbox!']);
  console.log(await result.stdout());
}

The same on kosa8 Cloud (TypeScript, npm install @kosa8/sdk):

import { Kosa8Cloud } from '@kosa8/sdk';

const cloud = new Kosa8Cloud(); // reads KOSA8_API_KEY
const box = await cloud.sandboxes.create({ template: 'python' });
const r = await box.exec(['python3', '-c', "print('hello')"]);
console.log(r.exitCode, r.stdout);
await box.delete();

• runCommand(cmd, args) becomes exec([cmd, ...args]); stdout is a field, not a promise.
• sandbox.stop() becomes box.sleep() to keep the disk, or box.delete() [14].
• Vercel's network policy lists map to --egress-allow on a local sandbox, fixed at create [16].
• Each kosa8 Cloud exec runs in a fresh container on the sandbox's disk: files under /workspace persist between commands, background processes do not. A buffered exec stops at 90 seconds; send stream: true for longer commands [14].
• Templates today are base (Alpine), python (Python 3.12) and node (Node.js 22) [14].
• An organization runs up to 20 sandboxes at once on kosa8 Cloud unless you ask for more [15].

06Questions

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