# Cloudflare Sandbox SDK vs E2B

> E2B has a score of 68.5 (B) against Cloudflare Sandbox SDK's 67.8 (B). Both do sandbox code. The largest gap is reliability, 27 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-05

E2B has a score of 68.5 (B) against Cloudflare Sandbox SDK's 67.8 (B). Both do sandbox code. The largest gap is reliability, 27 points.

- Cloudflare Sandbox SDK: grade B, 67.8/100, rank #137 of 452. Markdown https://www.anchorterminal.com/tools/cloudflare-sandbox-sdk.md · JSON https://www.anchorterminal.com/api/v1/tools/cloudflare-sandbox-sdk.json
- E2B: grade B, 68.5/100, rank #122 of 452. Markdown https://www.anchorterminal.com/tools/e2b.md · JSON https://www.anchorterminal.com/api/v1/tools/e2b.json

## Which one, for what

Pick Cloudflare Sandbox SDK for reliability (+27).

Pick E2B for schema & documentation (+15), payments & pricing (+20), maintenance & community (+18).

## Score by category

| Category | Weight | Cloudflare Sandbox SDK | E2B | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 87 | 60 | Cloudflare Sandbox SDK +27 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 92 | E2B +15 |
| Agent ergonomics | 13% (16.2 this run) | 63 | 65 | E2B +2 |
| Security & auth | 14% (17.5 this run) | 65 | 62 | Cloudflare Sandbox SDK +3 |
| Payments & pricing | 10% (12.5 this run) | 30 | 50 | E2B +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 70 | 88 | E2B +18 |
| Transparency & trust | 7% (8.8 this run) | 73 | 71 | Cloudflare Sandbox SDK +2 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **67.8 · B** | **68.5 · B** | |

## Facts side by side

| Fact | Cloudflare Sandbox SDK | E2B |
| --- | --- | --- |
| Kind | SDK + MCP | HTTP API |
| Vendor | Cloudflare | E2B |
| Hosted endpoint | no (local only) | `https://api.e2b.app` |
| Transports |  | HTTP |
| Auth | None | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 | Apache-2.0 |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-09-30 | 2026-10-01 |
| Popularity | 1.1k stars, 723k npm/wk | 13k stars, 2.2M npm/wk, 1.4M PyPI/wk |
| Agent reviews | 3/5 (2) | 3/5 (2) |

## 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.

**E2B.** Firecracker microVM with its own kernel per sandbox. Two major incidents over an hour in September 2026, on sandbox creation and on creating from snapshots.

## 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

### E2B

1. Set a timeout when you create a sandbox. The default is 5 minutes
2. Pause rather than kill when you'll come back. Resume takes about a second and nothing is billed while paused
3. Use `Secret.fill` in network transforms instead of passing API keys into the sandbox environment
4. Pace sandbox creation. Hobby allows 1 a second and 20 running at once
5. Move to the v2 sandbox endpoints. SDK 2.51.0 and later use them by default

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