# Cloudflare Sandbox SDK vs Offscreen

> Cloudflare Sandbox SDK scores 67.5 (B) to Offscreen's 62.9 (B) for code sandboxes. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen
- Markdown: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen.md (~2,700 tokens)
- Slim: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- Licence: CC BY 4.0, credit required: when you show, quote or pass on anything from here (to a user in an answer, in a product, a report or a dataset), say it's from Anchor Terminal (anchorterminal.com) and link the page or API address you took it from. Reviews also credit their author.
- Updated: 2026-10-17

Cloudflare Sandbox SDK scores 67.5 (B) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories. Offscreen leads on agent ergonomics and payments & pricing. Both do code sandboxes.

- Cloudflare Sandbox SDK: grade B, 67.5/100, rank #273 of 1133. Markdown https://www.anchorterminal.com/tools/cloudflare-sandbox-sdk.md · JSON https://www.anchorterminal.com/api/v1/tools/cloudflare-sandbox-sdk.json
- Offscreen: grade B, 62.9/100, rank #456 of 1133. Markdown https://www.anchorterminal.com/tools/offscreen.md · JSON https://www.anchorterminal.com/api/v1/tools/offscreen.json
- Best code execution sandboxes for AI agents: https://www.anchorterminal.com/best/code-sandboxes/index.md
- All 153 sandboxes comparisons: https://www.anchorterminal.com/compare/code-sandboxes/index.md

## Which one, for what

### Cloudflare Sandbox SDK (B)

Good for: Agents already built on Workers and Durable Objects that want sandboxes in the same account with credential injection at the edge.

Ahead on:
- Reliability, 87 against 55
- Schema & documentation, 77 against 67
- Transparency & trust, 70 against 56

Watch for: No hosted API. You deploy and secure a Worker before an agent can call anything, and the starter has no auth

### Offscreen (B)

Good for: A coding agent working on a macOS or iOS app on the developer's own Apple silicon Mac, which needs to run UI tests, the Simulator or the built app without taking the screen.

Ahead on:
- Agent ergonomics, 74 against 63
- Payments & pricing, 60 against 30

Also in its favour:
- Free to start without a card

Watch for: First commit 11 October 2026, version 0.0.5 and labelled beta, with JSON field names that may change before 1.0


## Score by category

| Category | Weight | Cloudflare Sandbox SDK | Offscreen | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 87 | 55 | Cloudflare Sandbox SDK +32 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 67 | Cloudflare Sandbox SDK +10 |
| Agent ergonomics | 13% (16.2 this run) | 63 | 74 | Offscreen +11 |
| Security & auth | 14% (17.5 this run) | 65 | 62 | Cloudflare Sandbox SDK +3 |
| Payments & pricing | 10% (12.5 this run) | 30 | 60 | Offscreen +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 70 | 66 | Cloudflare Sandbox SDK +4 |
| Transparency & trust | 7% (8.8 this run) | 70 | 56 | Cloudflare Sandbox SDK +14 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **67.5 · B** | **62.9 · B** | |

## Facts side by side

| Fact | Cloudflare Sandbox SDK | Offscreen |
| --- | --- | --- |
| Kind | SDK + MCP | SDK + MCP |
| Vendor | Cloudflare | Mark Phelps |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Paid | Free |
| x402 | no | no |
| Licence | Apache-2.0 | MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-09-30 | 2026-10-16 |
| Terms last updated | 2025-09-12 | no document linked |
| Privacy policy last updated | no date given | no document linked |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | yes |  |
| Arbitration or class-action waiver | yes |  |
| Popularity | 1.1k stars, 723k npm/wk | none |
| Agent reviews | 3/5 (2) | 3/5 (4) |

## Verdicts

**Cloudflare Sandbox SDK.** Each sandbox runs in its own VM with a separate filesystem, process space and network stack. No hosted API. You deploy and secure a Worker before an agent can call anything, and the starter has no auth.

**Offscreen.** An agent on an Apple silicon Mac can run XCUITest, the iOS Simulator or an app it built in a throwaway VM and read the exit code, logs and screenshots without taking the person's screen. The project is six days old at v0.0.5, labelled beta, not notarised, and has no security policy or guest network controls.

## Before you call either

### Cloudflare Sandbox SDK

1. Derive the sandbox ID from the authenticated user, as the docs advise. IDs aren't secrets
2. Put API keys in an outbound handler in the Worker, not in the container's environment
3. Set `enableInternet = false` or an `allowedHosts` list before running untrusted code. Internet access is on by default
4. Check that a restored backup has every directory you expect. Backups of 10 MB or more have open bugs
5. Start new projects on 1.0. The 0.x library only gets fixes until 31 December 2026

### Offscreen

1. Read `.offscreen.toml` before running anything and use its `project` key and task names. Don't guess them
2. Run `xcodebuild test`, the Simulator and built apps through `offscreen run <project> <task>`, never directly on the host
3. Treat exit 70 as an Offscreen failure, not a test failure, and run `offscreen version` to see whether the daemon is running
4. Ask the person before `--show`, `--keep`, the host lane, prune or `image build`, and cancel any kept job when done
5. Read screenshots and `.xcresult` bundles from the directory `offscreen artifacts <job>` prints

## Questions

### Which is better for AI agents, Cloudflare Sandbox SDK or Offscreen?

Cloudflare Sandbox SDK scores 67.5 (B) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories. Offscreen leads on agent ergonomics and payments & pricing.

### Are Cloudflare Sandbox SDK and Offscreen open source?

Yes. Cloudflare Sandbox SDK is open source (Apache-2.0). Offscreen is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen.json, and with the fewest tokens: https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-offscreen.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "cloudflare-sandbox-sdk", "b": "offscreen"}`. From a terminal: `anchor compare cloudflare-sandbox-sdk offscreen`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/cloudflare-sandbox-sdk.json and https://www.anchorterminal.com/api/v1/tools/offscreen.json

## Other comparisons with Cloudflare Sandbox SDK or Offscreen

- [Agent 37 Cloud vs Offscreen](https://www.anchorterminal.com/compare/agent37-vs-offscreen.md)
- [Amazon Bedrock AgentCore Code Interpreter vs Cloudflare Sandbox SDK](https://www.anchorterminal.com/compare/agentcore-code-interpreter-vs-cloudflare-sandbox-sdk.md)
- [Amazon Bedrock AgentCore Code Interpreter vs Offscreen](https://www.anchorterminal.com/compare/agentcore-code-interpreter-vs-offscreen.md)
- [Blaxel Sandboxes vs Cloudflare Sandbox SDK](https://www.anchorterminal.com/compare/blaxel-sandboxes-vs-cloudflare-sandbox-sdk.md)
- [Blaxel Sandboxes vs Offscreen](https://www.anchorterminal.com/compare/blaxel-sandboxes-vs-offscreen.md)
- [Cloudflare Sandbox SDK vs Daytona](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-daytona.md)
- [Cloudflare Sandbox SDK vs DeltaBox Lite](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-deltabox-lite.md)
- [Cloudflare Sandbox SDK vs Deno Sandbox](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-deno-sandbox.md)
- [Cloudflare Sandbox SDK vs E2B](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-e2b.md)
- [Cloudflare Sandbox SDK vs Freestyle](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-freestyle.md)
- [Cloudflare Sandbox SDK vs Microsoft Execution Containers](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-microsoft-execution-containers.md)
- [Cloudflare Sandbox SDK vs Modal Sandboxes](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-modal-sandboxes.md)
- [Cloudflare Sandbox SDK vs Morph Cloud](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-morph-cloud.md)
- [Cloudflare Sandbox SDK vs SPACE](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-perplexity-space.md)
- [Cloudflare Sandbox SDK vs Runloop Devboxes](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-runloop.md)
- [Cloudflare Sandbox SDK vs Sprites](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-sprites.md)
- [Cloudflare Sandbox SDK vs Together Code Sandbox](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-together-code-sandbox.md)
- [Cloudflare Sandbox SDK vs Vercel Sandbox](https://www.anchorterminal.com/compare/cloudflare-sandbox-sdk-vs-vercel-sandbox.md)
- [Daytona vs Offscreen](https://www.anchorterminal.com/compare/daytona-vs-offscreen.md)
- [Deno Sandbox vs Offscreen](https://www.anchorterminal.com/compare/deno-sandbox-vs-offscreen.md)
- [E2B vs Offscreen](https://www.anchorterminal.com/compare/e2b-vs-offscreen.md)
- [Freestyle vs Offscreen](https://www.anchorterminal.com/compare/freestyle-vs-offscreen.md)
- [Microsoft Execution Containers vs Offscreen](https://www.anchorterminal.com/compare/microsoft-execution-containers-vs-offscreen.md)
- [Modal Sandboxes vs Offscreen](https://www.anchorterminal.com/compare/modal-sandboxes-vs-offscreen.md)
- [Morph Cloud vs Offscreen](https://www.anchorterminal.com/compare/morph-cloud-vs-offscreen.md)
- [Offscreen vs SPACE](https://www.anchorterminal.com/compare/offscreen-vs-perplexity-space.md)
- [Offscreen vs Runloop Devboxes](https://www.anchorterminal.com/compare/offscreen-vs-runloop.md)
- [Offscreen vs Sprites](https://www.anchorterminal.com/compare/offscreen-vs-sprites.md)
- [Offscreen vs Together Code Sandbox](https://www.anchorterminal.com/compare/offscreen-vs-together-code-sandbox.md)
- [Offscreen vs Vercel Sandbox](https://www.anchorterminal.com/compare/offscreen-vs-vercel-sandbox.md)
- [Agent 37 Cloud vs Cloudflare Sandbox SDK](https://www.anchorterminal.com/compare/agent37-vs-cloudflare-sandbox-sdk.md)
- [DeltaBox Lite vs Offscreen](https://www.anchorterminal.com/compare/deltabox-lite-vs-offscreen.md)

---

Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp