# Celesto (formerly SmolVM) (slim)

> Celesto, formerly SmolVM, is an open-source Python SDK and CLI from Celesto AI that runs disposable Firecracker or QEMU microVMs on the owner's machine for agent code, browsers and desktops, with an optional paid Celesto Cloud.

- Full: https://www.anchorterminal.com/tools/celesto.md (~7,150 tokens) · this version ~1,430 tokens · JSON https://www.anchorterminal.com/tools/celesto.json · canonical https://www.anchorterminal.com/tools/celesto
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07 · pricing https://www.anchorterminal.com/tools/celesto#pricing · reviews https://www.anchorterminal.com/tools/celesto#reviews
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

**B · 68/100 · rank #298 of 1486 · #6 in Code execution sandboxes · not agent-ready · confidence medium**


Assessment: Celesto runs each agent task in a local Firecracker or QEMU microVM with its own kernel, driven by a CLI with a stable JSON envelope and a Python SDK, free under Apache-2.0. It is pre-1.0, renamed from SmolVM on 19 September 2026, sends usage telemetry after a first-use notice, and leaves outbound networking open unless a mode is set.

## Facts

- Kind: SDK + MCP · vendor: Celesto AI, Inc. · category: Code execution sandboxes · legal entity: Celesto AI, Inc. · provenance 66/100
- Packages: pypi `celesto`
- Auth: None · pricing: Freemium · x402: no · licence: Apache-2.0
- Benchmark probes: not run yet, so Performance is pending
- Surface listed: The open-source `celesto` Python SDK and CLI 0.1.13 running local microVMs, read from a clone of github.com/CelestoAI/Celesto, PyPI, celesto.ai and its llms.txt, pricing, security and privacy pages on 6 November 2026. Celesto Cloud and the hosted MCP server were read for pricing only. Nothing was installed or run
- Which product: SmolVM, the lead's name, is the same repository renamed Celesto on 19 September 2026. The slug follows the current name
- Runtimes: Minimal computer (`Computer()`), browser session with Chromium and CDP, Linux desktop, Windows computer from an image, and macOS desktop on Apple Silicon
- Hosts: Python 3.11 or newer on Linux and macOS. macOS setup installs QEMU through Homebrew; Linux setup may ask for sudo
- TypeScript SDK: `@celestoai/celesto` 0.1.0-preview.1, an alpha installed from a GitHub release tarball, not npm
- Celesto Cloud prices: Micro $0.015, Small $0.020, Standard $0.030, Memory $0.040, Large $0.080, XL $0.160 per running hour. Up to 10 running sandboxes on paid accounts, one on the trial. Stopped root disks kept free for 30 days
- Legal entity: Celesto AI, Inc., a Delaware corporation, per the privacy policy of 30 October 2026
- Prices: Cloud Micro sandbox (1 vCPU, 2 GB) $0.015 per session-hour; Cloud XL sandbox (8 vCPU, 32 GB) $0.16 per session-hour

- Scores: Reliability 66, Performance pending, Schema & documentation 85, Agent ergonomics 69, Security & auth 52, Payments & pricing 60, Task success pending, Maintenance & community 81, Transparency & trust 70 · total over the 7 assessed categories
- Why: Reliability, Read with the local-software lines, because the graded surface runs on the owner's machine. · Schema & documentation, Read as an SDK and CLI. · Agent ergonomics, A CLI and SDK add no tool definitions to an agent's context. · Security & auth, Framework reading for local software. · Payments & pricing, Read with the self-hosted rule, scoring the hosted option for the price lines. · Maintenance & community, 0.1.13 on PyPI on 5 November 2026, tagged 6 November (30). · Transparency & trust, Apache-2.0 in LICENSE and on PyPI (30).
- Sources: 9, open questions: 7, both in the full twin
- Capabilities: sandbox.code, sandbox.fs, sandbox.persist, sandbox.browser
- JSON: https://www.anchorterminal.com/api/v1/tools/celesto.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/celesto.svg` or a link to https://www.anchorterminal.com/tools/celesto from a page on celesto.ai or one of its subdomains, or the README at the root of github.com/CelestoAI/Celesto, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.
- Support: Discord https://discord.gg/KNb5UkrAmm; https://github.com/CelestoAI/Celesto/issues; https://celesto.ai/contact; more in the full twin

## Before you call it

1. Pass `--json` to every `celesto` command and branch on `ok` and `exit_code`, not on printed text
2. Create computers with unique names and delete them by exact name when the job ends, including after failures
3. Set `internet_settings={"mode": "off"}` or `restricted` for untrusted code, since the default is open
4. Set CELESTO_NO_TELEMETRY=1 in unattended runs if usage events must not leave the machine
5. Never paste browser or display connection URLs into model context; possession of the URL grants control

## Connect

```bash
pip install celesto && celesto setup && celesto doctor
```
Full config and headless snippets are in the full page. Through letme (picks today, calling later): https://letme.dev/celesto

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| E2B | BB | 70.1 | sandbox.code, sandbox.fs, sandbox.persist, sandbox.browser | https://www.anchorterminal.com/tools/e2b.min.md |
| Daytona | B | 67.7 | sandbox.code, sandbox.fs, sandbox.persist, sandbox.browser | https://www.anchorterminal.com/tools/daytona.min.md |
| Maritime | B | 67.5 | sandbox.code, sandbox.fs, sandbox.persist, sandbox.browser | https://www.anchorterminal.com/tools/maritime.min.md |
| Freestyle | C | 59.6 | sandbox.code, sandbox.fs, sandbox.persist, sandbox.browser | https://www.anchorterminal.com/tools/freestyle.min.md |
| Sandbox0 | C | 55.4 | sandbox.code, sandbox.persist, sandbox.fs, sandbox.browser | https://www.anchorterminal.com/tools/sandbox0.min.md |


## Panel reviews (0, desk reviews from public material, no calls made)