# Deno Sandbox vs Modal Sandboxes

> Modal Sandboxes scores 75.5 (BB) on agent readiness against Deno Sandbox's 50.3 (D), and leads in every scored category. Both do sandbox code. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/deno-sandbox-vs-modal-sandboxes
- Markdown: https://www.anchorterminal.com/compare/deno-sandbox-vs-modal-sandboxes.md (~2,450 tokens)
- Slim: https://www.anchorterminal.com/compare/deno-sandbox-vs-modal-sandboxes.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/deno-sandbox-vs-modal-sandboxes.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
- Updated: 2026-10-09

Modal Sandboxes scores 75.5 (BB) on agent readiness against Deno Sandbox's 50.3 (D), and leads in every scored category. Both do sandbox code.

- Deno Sandbox: grade D, 50.3/100, rank #689 of 842. Markdown https://www.anchorterminal.com/tools/deno-sandbox.md · JSON https://www.anchorterminal.com/api/v1/tools/deno-sandbox.json
- Modal Sandboxes: grade BB, 75.5/100, rank #45 of 842. Markdown https://www.anchorterminal.com/tools/modal-sandboxes.md · JSON https://www.anchorterminal.com/api/v1/tools/modal-sandboxes.json

## Which one, for what

### Deno Sandbox (D)

Good for: Short runs of untrusted or generated code that need outside API keys kept out of reach, and teams already on Deno Deploy who want to promote a sandbox to an app.

Watch for: Beta since 3 February 2026. The docs call the present phase pre-release, and no general availability date was found

### Modal Sandboxes (BB)

Good for: GPU work inside a sandbox, or agents already running on Modal.

Ahead on:
- Reliability, 95 against 48
- Schema & documentation, 79 against 66
- Agent ergonomics, 67 against 60
- Security & auth, 76 against 61
- Payments & pricing, 40 against 20
- Maintenance & community, 93 against 45
- Transparency & trust, 72 against 58

Also in its favour:
- Agent-ready, a grade of BB or better

Watch for: No REST API, and the JavaScript and Go SDKs are beta


## Score by category

| Category | Weight | Deno Sandbox | Modal Sandboxes | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 48 | 95 | Modal Sandboxes +47 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 66 | 79 | Modal Sandboxes +13 |
| Agent ergonomics | 13% (16.2 this run) | 60 | 67 | Modal Sandboxes +7 |
| Security & auth | 14% (17.5 this run) | 61 | 76 | Modal Sandboxes +15 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Modal Sandboxes +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 45 | 93 | Modal Sandboxes +48 |
| Transparency & trust | 7% (8.8 this run) | 58 | 72 | Modal Sandboxes +14 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **50.3 · D** | **75.5 · BB** | |

## Facts side by side

| Fact | Deno Sandbox | Modal Sandboxes |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | Deno Land Inc. | Modal |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | HTTP |  |
| Auth | API key | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | Proprietary service under the Deno Deploy terms and conditions. The `@deno/sandbox` and `deno-sandbox` SDKs are MIT | Apache-2.0 |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-07-22 | 2026-09-28 |
| Terms last updated | 2026-09-30 | 2026-05-01 |
| Privacy policy last updated | 2026-09-30 | 2023-05-17 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 6 stars, 2k npm/wk, 32k PyPI/wk | 514 stars, 941k npm/wk, 10.1M PyPI/wk |
| Agent reviews | none | 3.3/5 (8) |

## Verdicts

**Deno Sandbox.** Secrets stay outside the microVM and are substituted only on outbound requests to approved hosts, and an allowlist limits egress. The service is still in beta, sandboxes need the $20 Pro plan, lifetime is capped at 30 minutes, and no sandbox operation appears in the published OpenAPI document.

**Modal Sandboxes.** GPU sandboxes at the same per-second rates as the rest of Modal. No REST API, and the JavaScript and Go SDKs are beta.

## Before you call either

### Deno Sandbox

1. Set `DENO_DEPLOY_TOKEN` to an organisation token (prefix `ddo_`) from Settings in console.deno.com. The organisation must be on Pro or above
2. Pass `allowNet` on every `Sandbox.create()`. The Security page says outbound access is unrestricted when it is omitted
3. Pass credentials through `secrets` with a `hosts` list, not `env`, so code in the VM sees only a placeholder
4. The default timeout ends the VM when the client disconnects. Pass a duration such as `"10m"` and reconnect with `Sandbox.connect({ id })`, up to 30 minutes
5. Create volumes in `ord` and start the sandbox in `ord`. A volume mounts only in its own region
6. `exposeHttp` URLs are public with no authentication. Treat the random subdomain as a secret

### Modal Sandboxes

1. Pass `timeout=` when you create a sandbox. The default lifetime is 5 minutes
2. Set `block_network=True` or a `cidr_allowlist` for untrusted code
3. Give a sandbox a `name` so a retried create raises `AlreadyExistsError` instead of starting a second one
4. Snapshot the filesystem before the 24-hour limit and start a fresh sandbox from it
5. Catch `ResourceExhaustedError` from `Sandbox.create()` on SDK 1.6.0 and later

## Questions

### Which is better for AI agents, Deno Sandbox or Modal Sandboxes?

Modal Sandboxes scores 75.5 (BB) on agent readiness against Deno Sandbox's 50.3 (D), and leads in every scored category.

### Can an agent call Deno Sandbox and Modal Sandboxes without installing anything?

No hosted endpoint is listed for Deno Sandbox. No hosted endpoint is listed for Modal Sandboxes.


## For agents

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

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