--- title: Fly.io Machines slug: fly-machines url: "https://toolweight.com/options/fly-machines" homepage: "https://fly.io/docs/machines/" categories: sandbox-providers last_verified: 2026-07-23 license: CC-BY-4.0 --- # Fly.io Machines > Raw Firecracker microVMs with a REST API, durable volumes and 35+ regions. Fly Machines are Firecracker microVMs you start and stop over a REST API, with volumes, private networking and public IPs. Fly does not market this as a sandbox product and ships no agent SDK, so you supply the orchestration layer yourself. In exchange you get regional placement including Sydney, per-second billing, nothing charged while stopped, and 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 | | Brand | https://toolweight.com/vendors/Fly.io | | Compared in | 1 | ## Where it is compared ### [Sandbox providers](https://toolweight.com/compare/sandbox-providers) Ranked **#1 of 20** on default weights. | Field | Value | Confidence | Verified | Source | Note | | --- | --- | --- | --- | --- | --- | | Cold start | 900 ms | 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. | | Cold start (claimed) | 300 ms | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | Fly quotes roughly 250-300 ms to start a stopped Machine. | | Isolation | microvm | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | | Root in guest | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | | Egress control | allowlist | Inferred | - | - | Private networking, egress-only configurations and per-app IP control all exist, but you assemble them yourself. | | Max runtime | 1440 min | Inferred | - | - | No platform-imposed limit; Machines run until stopped. | | Persistent FS | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/volumes/ | Fly Volumes are durable NVMe attached to a Machine. | | Snapshot & fork | ◐ | Inferred | - | - | Volume snapshots and machine clone exist; no live memory fork. Suspend preserves memory state. | | Custom images | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/machines/ | - | | GPU | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/gpus/ | - | | Runtimes | any-oci-image | Inferred | - | - | - | | Preview URLs | ◐ | Inferred | - | - | Every app gets a fly.dev hostname, but per-sandbox public URLs are something you route yourself. | | Browser inside | ◐ | Inferred | - | - | Trivial to install, nothing supplied. | | File up/download | ◐ | Inferred | - | - | No file API. You use SSH, SFTP or a volume, fine for humans, awkward for agents. | | Sydney region | ● | Vendor-claimed | 2026-01-15 | https://fly.io/docs/reference/regions/ | syd. | | Concurrent limit | 500 sandboxes | Inferred | - | - | Org limits apply and are raised on request; the practical cap is your budget. | | MCP server | ◐ | Community-reported | - | - | flyctl ships MCP support aimed at managing Fly itself rather than driving sandboxes. | | SDKs | rest-api, cli | Inferred | - | - | - | | Streaming output | ◐ | Inferred | - | - | Logs stream and SSH exec works, but there is no exec-with-streaming primitive in the Machines API. | | 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. | | Meter | per-second | Vendor-claimed | 2026-01-15 | https://fly.io/docs/about/pricing/ | - | | 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. | | GitHub stars | - | Inferred | - | - | - | | Funding | series-c-plus | Community-reported | - | - | - | | Shipped | 2022 | Inferred | - | - | - | | Positioning | Hardware-virtualised containers that run anywhere, started and stopped over an API. | Inferred | - | - | - | **Verdict.** The best price-per-unit-of-isolation on this page by a wide margin, and the only mainstream option with a Sydney region. You pay for it in glue code: no file API, no exec streaming, no memory fork, no agent SDK. Budget a week to build the layer everyone else sells you. ## Alternatives - [ascii](https://toolweight.com/options/ascii), Agent orchestration over Telegram, running on box's VM infrastructure. - [Blaxel](https://toolweight.com/options/blaxel), Agent-first cloud claiming ~25 ms microVM boots from snapshots. - [box](https://toolweight.com/options/box), Persistent Linux VMs with SSH, per-VM IPv4 and disk-level forking, priced flat. - [Cloudflare Sandbox](https://toolweight.com/options/cloudflare-sandbox), Container sandboxes driven from a Worker, addressed through Durable Objects. - [CodeSandbox SDK](https://toolweight.com/options/codesandbox-sdk), Firecracker VMs with memory snapshots, from the online IDE, now owned by Together AI. - [Daytona](https://toolweight.com/options/daytona), Sub-second container sandboxes for agent workloads, from a team that built a dev-env manager. - [Self-hosted Firecracker](https://toolweight.com/options/diy-firecracker), The baseline: Firecracker on your own metal, plus every hard part you now own. - [E2B](https://toolweight.com/options/e2b), Open-source Firecracker sandboxes with Python and TypeScript SDKs for AI agents. - [exe.dev](https://toolweight.com/options/exe-dev), Persistent VMs you SSH into, with root, apt and systemd, on a flat monthly plan. - [Freestyle](https://toolweight.com/options/freestyle), Run untrusted JavaScript and full dev servers, with git hosting and domains built in. - [GitHub Codespaces](https://toolweight.com/options/github-codespaces), Devcontainer-backed cloud VMs built for humans, occasionally repurposed for agents. - [Islo](https://toolweight.com/options/islo), Per-agent isolated cloud sandboxes with enterprise policy controls, from Incredibuild. ## 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/options/fly-machines - Machine-readable: https://toolweight.com/options/fly-machines.md · https://toolweight.com/api/v1 · https://toolweight.com/mcp - toolweight takes no affiliate revenue and sells no placements. Corrections: https://toolweight.com/suggest