kosa8 vs Cloudflare Sandboxes

01The short verdict

Choose Cloudflare Sandboxes if

• your product already runs on Workers and Durable Objects [1];
• you want instances placed near users across Cloudflare's network without managing regions [4];
• you need large default capacity: 15,000 concurrent vCPU per account, raisable [12];
• SSO and account audit logs on every plan matter to you [8] [9].

Choose kosa8 if

• code must stay on your machine, your servers or an air-gapped site [15];
• you need to save memory and running processes and rewind to them [16];
• you want to fork a running sandbox into live copies [16];
• you want an audit log of what happened inside each sandbox, checkable by anyone [21].

02Cloudflare Sandboxes 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 Cloudflare Sandboxes is stronger

• Global placement. Instances start near the request across Cloudflare's network [4]; kosa8 Cloud has two regions [16].
• Capacity. Default account limits of 15,000 concurrent vCPU and 60 TiB memory, raisable [12]; kosa8 Cloud defaults to 20 sandboxes per organization [17].
• Platform fit. Sandboxes sit next to Workers, Durable Objects and the rest of Cloudflare, with free SSO and audit logs on all plans [8] [9].
• Compliance paperwork. A SOC 2 Type II report under NDA [11]; kosa8 has none yet [23].

04Where kosa8 is different

• Memory survives. Cloudflare snapshots capture the filesystem, not memory or processes [5]; kosa8 checkpoints capture all three [16].
• Any language, any host. kosa8 has five SDKs and an HTTP API, and needs no Worker in front [16].
• Off-cloud. Your computer, your servers or air-gapped [15].
• Inside-the-sandbox audit. Each kosa8 action lands in a hash-chained log [21].

05Moving from Cloudflare Sandboxes to kosa8

Cloudflare's Sandbox SDK 0.x quickstart gets a sandbox from a Durable Object binding inside a Worker and runs a command [13]. kosa8 Cloud is a plain HTTPS API, so the same code runs from a Worker, a server or a laptop.

Cloudflare Sandbox SDK 0.x, from its get-started page:

import { getSandbox, proxyToSandbox, type Sandbox } from "@cloudflare/sandbox";
const sandbox = getSandbox(env.Sandbox, "my-sandbox");
const result = await sandbox.exec('python3 -c "print(2 + 2)"');

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();

• There is no binding or Durable Object to declare; set KOSA8_API_KEY as a secret and call the API.
• exec('a string') becomes exec(['argv', 'list']); wrap a shell line as ['sh', '-c', '…'].
• destroy() becomes box.delete(), or box.sleep() to keep the disk [16].
• Cloudflare's outbound intercepts map to --egress-allow on a local sandbox [18]; kosa8 Cloud has no egress setting yet [19].
• 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 [16].
• Templates today are base (Alpine), python (Python 3.12) and node (Node.js 22) [16].
• An organization runs up to 20 sandboxes at once on kosa8 Cloud unless you ask for more [17].

06Questions

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