8 Best Fly.io Machines Alternatives (2026)
The closest alternatives to Fly.io Machines are ascii, Blaxel, box and Cloudflare Sandbox, with 4 more below. Each shares a comparison category with it, so every rationale here names both tools' real values. Fly.io Machines is 10th of 16 on Runtimes (any-oci-image), usually where a switch starts.
Why do people look for Fly.io Machines alternatives?
- Most people searching for Fly.io Machines alternatives are not shopping, they already run it and something has stopped fitting.
- That something is usually a specific number rather than a feeling.
- This page starts from the fields where Fly.io Machines genuinely trails the rosters it appears in, and only then covers the reasons that never show up in a table.
The measured reasons.
- Runtimes, any-oci-image, 10th of 16. E2B
records python, javascript-typescript, bash, any-oci-image.
- Any one of those is enough on its own if you sized your architecture around it.
- None of them is enough if you didn't, which is why the list is short and specific rather than a general case against Fly.io Machines.
The reasons that never make it into a table.
- A price rise after a funding round.
- A licence change that turns a self-host into a subscription.
- A region you now need and they do not have.
- An acquisition.
- A support experience that quietly degrades.
- None of those are fields, and all of them move teams, which is why every entry below links back to Sandbox providers, where the full field set and its sources live.
- The ones we catch get logged on the Fly.io Machines timeline.
How the shortlist is ordered.
- Every tool below shares at least one comparison category with Fly.io Machines, sorted by how many categories the two overlap in.
- There is no editorial ranking, no sponsorship and no affiliate link, the order is the overlap count.
- The rationale under each is generated from the two tools' own cells, so it names real values rather than adjectives.
1.
ascii
- ascii, Agent orchestration over Telegram, running on box's VM infrastructure.
- It meets Fly.io Machines in Sandbox providers.
- Against that: Meter (subscription, where Fly.io Machines records per-second) and Custom images (Partial, where Fly.io Machines records Yes).
- Best for you want an agent you message rather than an API you call.
- An agent harness with a VM attached, judged from an unverified vendor table with no fundamentals established.
Where ascii and Fly.io Machines actually differ
ascii profileCompare in Sandbox providers2.
Blaxel
- Blaxel, Agent-first cloud claiming ~25 ms microVM boots from snapshots.
- It meets Fly.io Machines in Sandbox providers.
- It is ahead on Runtimes (python, javascript-typescript, bash, any-oci-image against any-oci-image), Snapshot & fork (Yes against Partial) and Streaming output (Yes against Partial).
- What you give up: Egress control (open, where Fly.io Machines records allowlist) and Funding (seed, where Fly.io Machines records series-c-plus).
- Best for you want sandboxes, agent hosting and MCP from one vendor.
- The 25 ms claim measures the wrong operation, and the broad platform is a lot to buy from a seed-stage company.
Where Blaxel and Fly.io Machines actually differ
Blaxel profileCompare in Sandbox providers- Egress control
- openFly.io Machines: allowlist Inferred
- Runtimes
- pythonjavascript-typescript+2Fly.io Machines: any-oci-image Inferred
- Funding
- seedFly.io Machines: series-c-plus Community-reported
- Streaming output
- YesFly.io Machines: Partial Inferred
- Persistent FS
- PartialFly.io Machines: Yes Inferred
3.
box
- box, Persistent Linux VMs with SSH, per-VM IPv4 and disk-level forking, priced flat.
- It meets Fly.io Machines in Sandbox providers.
- Against that: Meter (subscription, where Fly.io Machines records per-second) and Custom images (Partial, where Fly.io Machines records Yes).
- Best for you want a VM that stays up rather than a sandbox that vanishes.
- A coherent long-lived-VM pitch, but a vendor self-assessment with no measured isolation, boot time or price.
Where box and Fly.io Machines actually differ
box profileCompare in Sandbox providers4.
Cloudflare Sandbox
- Cloudflare Sandbox, Container sandboxes driven from a Worker, addressed through Durable Objects.
- It meets Fly.io Machines in Sandbox providers.
- It is ahead on Streaming output (Yes against Partial), Preview URLs (Yes against Partial) and File up/download (Yes against Partial).
- What you give up: Isolation (container, where Fly.io Machines records microvm) and Persistent FS (No, where Fly.io Machines records Yes).
- Best for your app already runs on Workers and Durable Objects.
- An addressable sandbox object in your app, worth it on Workers but too slow to migrate to.
Where Cloudflare Sandbox and Fly.io Machines actually differ
Cloudflare Sandbox profileCompare in Sandbox providers- Persistent FS
- NoFly.io Machines: Yes Inferred
- Max runtime
- 60minFly.io Machines: 1440 min Inferred
- GPU
- NoFly.io Machines: Yes Inferred
- Snapshot & fork
- NoFly.io Machines: Partial Inferred
5.
CodeSandbox SDK
- CodeSandbox SDK, Firecracker VMs with memory snapshots, from the online IDE, now owned by Together AI
. - It meets Fly.io Machines in Sandbox providers.
- It is ahead on Runtimes (python, javascript-typescript, bash, any-oci-image against any-oci-image), Snapshot & fork (Yes against Partial) and Streaming output (Yes against Partial).
- What you give up: Egress control (open, where Fly.io Machines records allowlist) and GPU (No, where Fly.io Machines records Yes).
- Best for you fork one prepared environment many times.
- The best-engineered snapshot-and-fork here for branching workloads, now a component of Together AI rather than its own product.
Where CodeSandbox SDK and Fly.io Machines actually differ
CodeSandbox SDK profileCompare in Sandbox providers- Egress control
- openFly.io Machines: allowlist Inferred
- GPU
- NoFly.io Machines: Yes Inferred
- Sydney region
- NoFly.io Machines: Yes Inferred
- Runtimes
- pythonjavascript-typescript+2Fly.io Machines: any-oci-image Inferred
- MCP server
- NoFly.io Machines: Partial Inferred
6.
Daytona
- Daytona, Sub-second container sandboxes for agent workloads, from a team that built a dev-env manager.
- It meets Fly.io Machines in Sandbox providers.
- It is ahead on Runtimes (python, javascript-typescript, bash, any-oci-image against any-oci-image), Snapshot & fork (Yes against Partial) and Streaming output (Yes against Partial).
- What you give up: Isolation (container, where Fly.io Machines records microvm) and Sydney region (No, where Fly.io Machines records Yes).
- Best for boot time is your headline metric and the code is your own.
- E2B's most credible ergonomics challenger with the best MCP story, but shared-kernel containers make it wrong for untrusted code.
Where Daytona and Fly.io Machines actually differ
Daytona profileCompare in Sandbox providers- Sydney region
- NoFly.io Machines: Yes Inferred
- Runtimes
- pythonjavascript-typescript+2Fly.io Machines: any-oci-image Inferred
- Funding
- seedFly.io Machines: series-c-plus Community-reported
7.
Self-hosted Firecracker
- Self-hosted Firecracker, The baseline: Firecracker on your own metal, plus every hard part you now own.
- It meets Fly.io Machines in Sandbox providers.
- It is ahead on Concurrent limit (1,000 sandboxes against 500 sandboxes).
- What you give up: Idle cost (full-rate, where Fly.io Machines records free-when-stopped) and Meter (per-hour, where Fly.io Machines records per-second).
- Best for sustained volume where vendor margin exceeds an engineer's salary.
- The honest baseline: identical isolation at a tenth the cost, minus the two engineer-years of orchestration.
- Note that we carry Self-hosted Firecracker as the do-it-yourself baseline in that roster, the "what if we just ran this ourselves" reference point.
- The honest answer is usually that it is cheaper and considerably more work.
Where Self-hosted Firecracker and Fly.io Machines actually differ
Self-hosted Firecracker profileCompare in Sandbox providers- Idle cost
- full-rateFly.io Machines: free-when-stopped Inferred
- Meter
- per-hourFly.io Machines: per-second Inferred
- Streaming output
- NoFly.io Machines: Partial Inferred
- Preview URLs
- NoFly.io Machines: Partial Inferred
- MCP server
- NoFly.io Machines: Partial Inferred
- File up/download
- NoFly.io Machines: Partial Inferred
8.E2B
- E2B, Open-source Firecracker sandboxes with Python and TypeScript SDKs for AI agents.
- It meets Fly.io Machines in Sandbox providers.
- It is ahead on Runtimes (python, javascript-typescript, bash, any-oci-image against any-oci-image), Streaming output (Yes against Partial) and Preview URLs (Yes against Partial).
- What you give up: Egress control (open, where Fly.io Machines records allowlist) and GPU (No, where Fly.io Machines records Yes).
- Best for you want the category default with a real self-host escape hatch.
- The safest default: complete SDKs, Dockerfile templates and an Apache licence, though no longer fastest and weak at hobby scale.
Where E2B and Fly.io Machines actually differ
E2B profileCompare in Sandbox providers- Egress control
- openFly.io Machines: allowlist Inferred
- GPU
- NoFly.io Machines: Yes Inferred
- Sydney region
- NoFly.io Machines: Yes Inferred
- Runtimes
- pythonjavascript-typescript+2Fly.io Machines: any-oci-image Inferred
- Persistent FS
- PartialFly.io Machines: Yes Inferred
How this list was built
There is no editorial ranking on this page and no sponsorship behind it. The order is mechanical: every tool that shares a comparison category with Fly.io Machines, sorted by how many categories the two overlap in. A tool that meets Fly.io Machines in three rosters sits above one that meets it in a single roster, because more overlap means the comparison is more like-for-like.
The rationale under each entry is composed from the two tools' own cells. Where they differ on a field we score, the sentence names both values and the unit. Where they don't differ, it says so instead of manufacturing a distinction, which is why some entries are short.
Values, sources and verification dates all live on the category tables: Sandbox providers. If a figure here disagrees with a vendor's current pricing page, the vendor is right and we are stale.
Still deciding whether to move at all? The Fly.io Machines profile has the when-to-use and when-not-to-use blocks, and the Fly.io Machines timeline has the dated changes that usually trigger a migration.