---
title: Fly.io Machines
slug: fly-machines
url: "https://toolweight.com/tools/fly-machines"
homepage: "https://fly.io/docs/machines/"
categories: sandbox-providers
last_verified: 2026-07-23
dataset_version: 0738be72
license: CC-BY-4.0
---

# Fly.io Machines

> Raw Firecracker microVMs with a REST API, durable volumes and 35+ regions.

- Firecracker microVMs started and stopped over a REST API, with volumes, private networking and public IPs
- Not marketed as a sandbox and ships no agent SDK, so you supply orchestration yourself
- Regional placement including Sydney, per-second billing, nothing charged while stopped
- Pricing roughly an order of magnitude below the agent-native vendors

## Identity

|  |  |
| --- | --- |
| Name | Fly.io Machines |
| Company | Fly.io |
| One-liner | Raw Firecracker microVMs with a REST API, durable volumes and 35+ regions. |
| Site | https://fly.io/docs/machines/ |
| Docs | https://fly.io/docs/machines/api/ |
| Founded | 2017 |
| Funding | Series C |
| Compared in | 1 |

## Where it is compared

### [Sandbox providers](https://toolweight.com/compare/sandbox-providers)
Ranked **#1 of 19** on default weights.
| Field | Value | Confidence | Verified | Source | Note | Permalink |
| --- | --- | --- | --- | --- | --- | --- |
| Cold start | 900ms | Inferred | - | - | Estimate for starting a stopped Machine plus the API round trip. Suspend/resume is materially faster; a cold create with an image pull is slower. | https://toolweight.com/compare/sandbox-providers#fly-machines--cold_start_measured |
| Cold start (claimed) | 300ms | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | Fly quotes roughly 250-300 ms to start a stopped Machine. | https://toolweight.com/compare/sandbox-providers#fly-machines--cold_start_claimed |
| Isolation | microvm | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | https://toolweight.com/compare/sandbox-providers#fly-machines--isolation_tech |
| Root in guest | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | https://toolweight.com/compare/sandbox-providers#fly-machines--root_access |
| Egress control | allowlist | Inferred | - | - | Private networking, egress-only configurations and per-app IP control all exist, but you assemble them yourself. | https://toolweight.com/compare/sandbox-providers#fly-machines--egress_control |
| Max runtime | 24h | Inferred | - | - | No platform-imposed limit; Machines run until stopped. | https://toolweight.com/compare/sandbox-providers#fly-machines--max_runtime |
| Persistent FS | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/volumes/ | Fly Volumes are durable NVMe attached to a Machine. | https://toolweight.com/compare/sandbox-providers#fly-machines--persistent_fs |
| Snapshot & fork | ◐ | Inferred | - | - | Volume snapshots and machine clone exist; no live memory fork. Suspend preserves memory state. | https://toolweight.com/compare/sandbox-providers#fly-machines--snapshot_fork |
| Custom images | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | https://toolweight.com/compare/sandbox-providers#fly-machines--custom_images |
| GPU | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/gpus/ | - | https://toolweight.com/compare/sandbox-providers#fly-machines--gpu |
| Runtimes | any-oci-image | Inferred | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--language_runtimes |
| Preview URLs | ◐ | Inferred | - | - | Every app gets a fly.dev hostname, but per-sandbox public URLs are something you route yourself. | https://toolweight.com/compare/sandbox-providers#fly-machines--preview_urls |
| Browser inside | ◐ | Inferred | - | - | Trivial to install, nothing supplied. | https://toolweight.com/compare/sandbox-providers#fly-machines--browser_in_sandbox |
| File up/download | ◐ | Inferred | - | - | No file API. You use SSH, SFTP or a volume, fine for humans, awkward for agents. | https://toolweight.com/compare/sandbox-providers#fly-machines--file_transfer_api |
| Sydney region | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/reference/regions/ | syd. | https://toolweight.com/compare/sandbox-providers#fly-machines--sydney_region |
| Concurrent limit | 500 sandboxes | Inferred | - | - | Org limits apply and are raised on request; the practical cap is your budget. | https://toolweight.com/compare/sandbox-providers#fly-machines--max_concurrency |
| MCP server | ◐ | Community-reported | - | - | flyctl ships MCP support aimed at managing Fly itself rather than driving sandboxes. | https://toolweight.com/compare/sandbox-providers#fly-machines--mcp_server |
| SDKs | rest-api, cli | Inferred | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--sdk_languages |
| Streaming output | ◐ | Inferred | - | - | Logs stream and SSH exec works, but there is no exec-with-streaming primitive in the Machines API. | https://toolweight.com/compare/sandbox-providers#fly-machines--streaming_stdout |
| Price / hour | $0.031/hr | Vendor-claimed | 2026-07-23 | https://fly.io/docs/about/pricing/ | Read straight off the preset table rather than derived: shared-cpu-2x with 4 GB is listed at $0.0309/hr ($0.00000857/s, $22.22/mo) in the cheapest region. Performance CPUs cost several times more, and regional multipliers apply, Sydney is dearer than Amsterdam. | https://toolweight.com/compare/sandbox-providers#fly-machines--price_per_hour |
| Meter | per-second | Vendor-claimed | 2026-01-15 | https://fly.io/docs/about/pricing/ | - | https://toolweight.com/compare/sandbox-providers#fly-machines--billing_granularity |
| Idle cost | free-when-stopped | Vendor-claimed | 2026-01-15 | https://fly.io/docs/about/pricing/ | A stopped Machine costs nothing beyond its rootfs and volumes. | https://toolweight.com/compare/sandbox-providers#fly-machines--idle_billing |
| GitHub stars | - | Inferred | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--github_stars |
| Funding | series-c-plus | Community-reported | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--funding_stage |
| Shipped | 2022 | Inferred | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--launched |
| Positioning | Hardware-virtualised containers that run anywhere, started and stopped over an API. | Inferred | - | - | - | https://toolweight.com/compare/sandbox-providers#fly-machines--positioning |

**Verdict.** Unbeatable price-per-isolation and the only mainstream Sydney region, paid for in a week of glue code.

## Alternatives

- [Blaxel](https://toolweight.com/tools/blaxel), Agent-first cloud claiming ~25 ms microVM boots from snapshots.
- [boat](https://toolweight.com/tools/boat), Persistent Ubuntu VMs for agents with SSH, Docker and disk-level fork, billed per second.
- [Cloudflare Sandbox](https://toolweight.com/tools/cloudflare-sandbox), Container sandboxes driven from a Worker, addressed through Durable Objects.
- [CodeSandbox SDK](https://toolweight.com/tools/codesandbox-sdk), Firecracker VMs with memory snapshots, from the online IDE, now owned by Together AI.
- [Daytona](https://toolweight.com/tools/daytona), Sub-second container sandboxes for agent workloads, from a team that built a dev-env manager.
- [Self-hosted Firecracker](https://toolweight.com/tools/diy-firecracker), The baseline: Firecracker on your own metal, plus every hard part you now own.
- [E2B](https://toolweight.com/tools/e2b), Open-source Firecracker sandboxes with Python and TypeScript SDKs for AI agents.
- [exe.dev](https://toolweight.com/tools/exe-dev), Persistent VMs you SSH into, with root, apt and systemd, on a flat monthly plan.
- [Freestyle](https://toolweight.com/tools/freestyle), Run untrusted JavaScript and full dev servers, with git hosting and domains built in.
- [GitHub Codespaces](https://toolweight.com/tools/github-codespaces), Devcontainer-backed cloud VMs built for humans, occasionally repurposed for agents.
- [Islo](https://toolweight.com/tools/islo), Per-agent isolated cloud sandboxes with enterprise policy controls, from Incredibuild.
- [Modal](https://toolweight.com/tools/modal), Serverless Python compute with a Sandbox API bolted onto a GPU-first platform.

## Logo & brand colours

SVG files: https://toolweight.com/teams/fly/logo.svg and https://toolweight.com/teams/fly/mono.svg. JSON: https://toolweight.com/api/v1/brands/fly.

| Hex | oklch |
| --- | --- |
| #ffffff | oklch(100.0% 0.000 0.0) |
| #ba7bf0 | oklch(69.5% 0.175 307.3) |
| #996bec | oklch(63.5% 0.188 297.2) |
| #5046e4 | oklch(51.0% 0.229 277.4) |

## Licence and attribution

Data from Toolweight (https://toolweight.com), licensed CC-BY-4.0.

- Licence: [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)
- Canonical HTML: https://toolweight.com/tools/fly-machines
- Machine-readable: https://toolweight.com/tools/fly-machines.md · https://toolweight.com/api/v1 · https://toolweight.com/mcp
- Toolweight takes no affiliate revenue and sells no placements.