Head to head · Code sandboxes · October 2026 research run

Celesto (formerly SmolVM) vs Morph Cloud

Celesto (formerly SmolVM) scores 68 (B) on agent readiness against Morph Cloud's 51.6 (D), and leads in every scored category. Both do code sandboxes.

Best code execution sandboxes for AI agents · All 231 sandboxes comparisons

Which one, for what

Celesto (formerly SmolVM) B

Best for Local microVM sandboxes for agent code, browsers and desktops on Linux and macOS, with a path to a hosted cloud.

Ahead on

  • Schema & documentation, 85 against 72
  • Agent ergonomics, 69 against 61
  • Security & auth, 52 against 39
  • Payments & pricing, 60 against 20
  • Maintenance & community, 81 against 48
  • Transparency & trust, 70 against 44

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • Open source

Watch for

Version 0.1.13 and declared pre-1.0 in SECURITY.md, with the TypeScript SDK an alpha installed from a GitHub tarball

Morph Cloud D

Best for Agents that need to checkpoint and fork a running machine with memory intact, for parallel attempts, evaluations or reinforcement learning rollouts.

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

No privacy policy, DPA or subprocessor list found on morph.so or cloud.morph.so. The terms of 23 October 2025 are the only legal document

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Payments & pricing Celesto (formerly SmolVM) +40

Celesto (formerly SmolVM) 60

Read with the self-hosted rule, scoring the hosted option for the price lines. No x402, MPP or L402 (0 of 40). Celesto Cloud publishes hourly prices for six sizes without a login (20). A one-time $5 Micro credit needs no card, and the local SDK is free (20). The graded local SDK installs from PyPI and runs with no account, so an agent needs no signup (20). Cloud use needs a browser signup and a card top-up. Total 60.

Morph Cloud 20

No x402, MPP or L402 found in the docs or the OpenAPI file on 8 October (0). Per the 8 October check, the pricing page defines the Morph Compute Unit (1 vCPU-hour with 4 GB RAM-hours and 16 GB disk-hours, or 5 TB snapshot-hours), states a standard rate of $0.05 an MCU and lists plans at $0, $40 and $250 a month without a login. The terms of 23 October 2025 add per-second compute billing and 30 days' notice of price changes (20). The Free plan starts with 0 MCUs and says to purchase MCUs to use compute. The FAQ refers readers to the billing console for any free credits (0). Signup is in a browser, and the key creation route needs an existing session or key (0). 0+20+0+0 = 20.

Maintenance & community Celesto (formerly SmolVM) +33

Celesto (formerly SmolVM) 81

0.1.13 on PyPI on 5 November 2026, tagged 6 November (30). 22 PyPI releases in the 90 days to 6 November (20). Most open issues are filed by maintainers. Outside reports such as the thread-safety issue got replies, and several recent ones have none yet; pull-request reply times were not read (15 of 25). The Python SDK is current, the TypeScript SDK is an alpha not published to npm (8 of 15). uv and Cargo lock files, CodeQL and publish workflows, with run results unread (8 of 10). Total 81.

Morph Cloud 48

The Python SDK repository tagged v0.1.116 on 20 October 2026, a generated release that adds disk resizing to the SDK and CLI, 15 days before this check. pypi.org did not resolve on 4 November, so its upload date there is unconfirmed (30). Three tagged Python releases in the 90 days from 6 August 2026, v0.1.114 on 30 August, v0.1.115 on 1 September and v0.1.116 on 20 October. v0.1.115 changes only the version and the minimum Python version in pyproject.toml, a packaging-only release that counts half, so the count is two and a half, below three (0). Scored on the closed-service scale. The changelog is not kept, per the 8 October check. The terms give ops@morph.so and the status page support@morph.so. The two open pull requests on the Python SDK (1 April and 14 September 2026) had no comments on 8 October, and GitHub's pages answered 403 on 4 November (4). The Python SDK and CLI are current. The TypeScript SDK repository's newest tag is v0.0.19 from 2 October 2025 and its newest commit 6 October 2025, matching 0.0.20 on npm on 8 October (10). The Python repository has 18 unit test files, but its only workflow is a publish job run by hand, so no public CI run was found (4). 30+0+4+10+4 = 48.

Transparency & trust Celesto (formerly SmolVM) +26

Celesto (formerly SmolVM) 70

Apache-2.0 in LICENSE and on PyPI (30). The privacy policy of 30 October 2026 links a subprocessor registry and describes the CLI telemetry in the same terms as the docs, but gives no retention periods beyond as long as necessary. Stopped cloud disks are kept 30 days per the pricing page (18 of 30). The changelog marks removals and the breaking rename, and the glossary lists older names still accepted, with no written deprecation policy (10 of 20). Telemetry is disclosed in the README, CLI reference and privacy policy, with three opt-outs, but it is on by default after the notice (16 of 20). Total 74.

Morph Cloud 44

The SDKs are Apache-2.0. The platform is closed, under Terms of Service last revised 23 October 2025 at cloud.morph.so/web/legal/terms-of-service, which name Morph Labs, Inc. of San Francisco, set California law and arbitration, and promise 15 days' notice of material changes (15). No privacy policy or DPA found. The terms say Morph staff do not access disk, memory or application data in instances except on a customer's time-bound request or by law, that such access is logged, that diagnostic artifacts are deleted per a retention schedule that is not published, and that usage telemetry is shared only aggregated or de-identified. The docs describe snapshot TTLs the customer sets and say Morph Actions data has no fixed retention period (8). No deprecation policy. The terms promise not to reduce core functionality materially during a committed billing term without a workaround or a refund, with no notice period for API changes. The OpenAPI file marks a few fields deprecated and keeps a legacy query alias, without dates (3). No subprocessor list or data location statement found (0). 15+8+3+0 = 26.

Schema & documentation Celesto (formerly SmolVM) +13

Celesto (formerly SmolVM) 85

Read as an SDK and CLI. The repository ships an OpenAPI document for the local server (24 operations) and the cloud API (171 operations), from which the TypeScript client is generated (25). llms.txt at celesto.ai, plus Markdown docs in the repository (10). The README's runtime table says when to use each runtime, and the automation section says to prefer exec and keep shell, ssh and desktop for interactive work (14 of 20). Network modes are closed values (open, off, public, restricted) and the SDK takes typed keyword arguments, though internet_settings is a plain dict (11 of 15). Examples directory, a JSON envelope for every command and documented cloud error fields such as required_scope, without a full error catalogue (12 of 15). Dated changelog and tags, pre-1.0 (13 of 15). Total 85.

Morph Cloud 72

Per the 8 October check, not re-read on 4 November. Public OpenAPI 3.1 file at cloud.morph.so/api/openapi.json with 52 paths and 69 operations (25). llms.txt and llms-full.txt under /docs (10). 67 of 69 operations have a description, many of one line, while the guides explain pause against stop and devboxes against instances (14). Enums for TTL action, HTTP auth mode and instance status, with patterns and ranges on names, ports and page sizes. Metadata is a free string map (12). Guides give Python, TypeScript and CLI examples. 37 operations document only a 422 beyond success, the error schema is detail with an optional error_code, and no error-code reference was found (8). The changelog page has one entry from 19 November 2024 and says it is not a complete history. The API path has no version and the SDK tags have no release notes (3). 25+10+14+12+8+3 = 72.

Security & auth Celesto (formerly SmolVM) +13

Celesto (formerly SmolVM) 52

Framework reading for local software. No credential is needed for local use, and the local API server and dashboard each require a bearer token, and cloud keys carry named permissions (22 of 30). Each computer has its own guest kernel, browser and display access uses capability URLs with a read-only option, and raw VNC is off. Against that, outbound networking is open by default and the restricting modes are opt-in (12 of 20). The security doc warns against giving connection URLs to a model as page content, but there is no guidance on treating command or page output as untrusted (5 of 15). computer logs shows startup output, with no audit log of commands (5 of 15). SECURITY.md with GitHub private vulnerability reporting and a supported-versions table, Security sections in the changelog, no security.txt, bug bounty or certification (8 of 20). Total 52.

Morph Cloud 39

Per the 8 October check of the docs, not re-read on 4 November. Bearer API keys bound to an organisation, listed with prefix and last-used time and deletable through the API. The docs mention key permissions in the dashboard without describing any. Devbox agent tokens are bound to one devbox with seven named scopes but do not expire. Short-lived delegation tokens exist for services (22). No read-only key for the instance API and no confirmation on stop or delete. Exposed HTTP services default to auth_mode: none, and the api_key mode asks callers to send the account's Morph API key to the service URL (8). Each instance is a full VM, but the docs name no isolation technology and no egress controls were found (5). Key last-used times, an organisation SSH key audit route and usage routes exist. No audit log of API calls found (4). security.txt returned 404 on cloud.morph.so and www.morph.so on 8 October. No disclosure policy, bug bounty or certification found. The terms list security controls and breach notification and offer "available third-party security attestations (e.g., SOC reports)" on request, without naming one (0). On 4 November osv.dev listed no advisory for morphcloud and the 2025 and 2026 CVE records named no Morph product. 22+8+5+4+0 = 39.

Agent ergonomics Celesto (formerly SmolVM) +8

Celesto (formerly SmolVM) 69

A CLI and SDK add no tool definitions to an agent's context. Collected command output is capped at 8 MiB with streaming as the alternative (18 of 25). computer list, logs --follow and name lookups, with little filtering (10 of 20). JSON errors carry a recovery command where Celesto has one, and cloud errors carry stable codes, operation and computer context and recovery fields since 0.1.7 (18 of 20). State-changing cloud requests are never replayed automatically and computers are addressed by unique names, but there are no idempotency keys (10 of 20). with Computer() creates and deletes a computer with no parameters, with Python and an alpha TypeScript SDK (13 of 15). Total 69.

Morph Cloud 61

Per the 8 October check of the OpenAPI file and docs, not re-read on 4 November. Instance and snapshot objects are bounded, list calls take a limit and a metadata filter, and there is no field selection. Exec returns stdout and stderr whole (15). /api/instance/list and /api/snapshot/list take page and limit (default 50, maximum 1,000) and a metadata filter. The older list routes are unpaginated (16). Newer routes document 400, 401, 402, 403, 404, 409 and 503 with a coded error body. Most routes document only 422, and no error reference was found (10). Idempotency-Key exists on API key creation only. Snapshot, branch, pause and reboot return Retry-After on a 503 refused before dispatch (8). Starting an instance needs only a snapshot id. Python SDK and CLI are current. The TypeScript SDK is 0.0.20 from 6 October 2025, the version the docs pin (12). 15+16+10+8+12 = 61.

Score by category

CategoryWeight this runCelesto (formerly SmolVM)Morph CloudEdge
Reliability16%206663Celesto (formerly SmolVM) +3
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28572Celesto (formerly SmolVM) +13
Agent ergonomics13%16.26961Celesto (formerly SmolVM) +8
Security & auth14%17.55239Celesto (formerly SmolVM) +13
Payments & pricing10%12.56020Celesto (formerly SmolVM) +40
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88148Celesto (formerly SmolVM) +33
Transparency & trust7%8.87044Celesto (formerly SmolVM) +26
Negative events≤1500
TotalB 68/100D 51.6/100

Facts side by side

FactCelesto (formerly SmolVM)Morph Cloud
KindSDK + MCPHTTP API
VendorCelesto AI, Inc.Morph Labs
Hosted endpointno (local only)https://cloud.morph.so/api
TransportsHTTP
AuthNoneAPI key
PricingFreemiumPay per use
x402nono
LicenceApache-2.0Proprietary hosted service under Morph Labs, Inc.'s Terms of Service (last revised 23 October 2025). The Python and TypeScript SDKs are Apache-2.0
Read-only variant documentednono
llms.txtyesyes
Last release2026-11-052026-10-20
Terms last updated2026-10-30not read yet
Privacy policy last updated2026-10-30no document linked
Customer content may train modelsnot found in the textnot read yet
Terms restrict automated accessnot found in the textnot read yet
Terms restrict benchmarkingnot found in the textnot read yet
Terms or service can change without noticenot found in the textnot read yet
Arbitration or class-action waivernot found in the textnot read yet
Popularity1.1k stars, 699 PyPI/wk3 stars, 339 npm/wk

How the scores have moved

Verdicts

Celesto (formerly SmolVM)

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.

Morph Cloud

Pause and snapshot keep memory and running processes, and one call branches an instance into several copies. A public OpenAPI file covers 69 operations. Terms from Morph Labs, Inc. are published, but no privacy policy or security page was found, the free plan includes no compute credit, and the changelog holds one entry from November 2024.

Before you call either

Celesto (formerly SmolVM)

  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

Morph Cloud

  1. Set ttl_seconds and ttl_action when starting an instance. Nothing in the docs stops an instance with no TTL from billing MCUs
  2. Pass auth_mode: api_key when exposing an HTTP service. The default is none, which makes the URL public
  3. Enable wake_on_ssh before calling exec on an instance that may be paused. There is no separate exec wake setting
  4. Use /api/instance/list and /api/snapshot/list with page and limit (default 50, maximum 1,000). The plain list routes return everything
  5. On a 503 from snapshot, branch, pause or reboot, wait for the Retry-After value before repeating the call

Questions

Which is better for AI agents, Celesto (formerly SmolVM) or Morph Cloud?

Celesto (formerly SmolVM) scores 68 (B) on agent readiness against Morph Cloud's 51.6 (D), and leads in every scored category.

Can an agent call Celesto (formerly SmolVM) and Morph Cloud without installing anything?

No hosted endpoint is listed for Celesto (formerly SmolVM). Morph Cloud has a hosted endpoint at https://cloud.morph.so/api.

Are Celesto (formerly SmolVM) and Morph Cloud open source?

Celesto (formerly SmolVM) is open source (Apache-2.0). No open-source release is listed for Morph Cloud.

Other comparisons with Celesto (formerly SmolVM) or Morph Cloud

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