Fly.io alternatives in 2026 14 agent sandboxes ranked by cost

What is the best alternative to Fly.io?

It depends on which Fly.io product you use and what you miss in it. For agents that mostly wait on a model, Runtime meters CPU the way a Sprite does, at lower rates: $0.64 for the job below, against $2.40 on Sprites and $1.53 on Machines. Stay on Machines if you need their 17 regions. Pick Cloudflare Sandbox to start near users from a Worker, Northflank to run in your own cloud account, and Daytona for GPUs or Windows.

Why do teams look beyond Fly.io?

Fly.io offers two ways to run agent code, and each has its own reason to move.

From Fly Machines, the general-purpose VMs:

• The whole size, every second. A Machine bills its size for as long as it is started, busy or not. An agent that spends most of a minute waiting on a model pays for two idle vCPUs.
• The root disk is temporary. Files outlive a Machine only on a volume, and suspend is a separate mechanism for keeping memory.
• Shared CPUs do not burst far. A shared-cpu-2x with 4 GB costs about $0.59 for the example, but its vCPUs are guaranteed 6.25% of a core each, so a new one would not fit 20 CPU-seconds into the minute.

From Fly Sprites, the sandboxes built for agents:

• Memory is the expensive part. $0.021875 per GB-hour of memory in use is about three times Runtime's $0.0075 per reserved GiB-hour, and it makes up $2.19 of the $2.40 example.
• Memory is Fly's to manage. A Sprite's memory is not a fixed figure to plan against, and it is dropped when the Sprite goes cold, at a time you do not choose.
• It stays awake after use. A Sprite keeps running, and billing, for about 30 seconds after its last activity, and Fly has no way to pause it sooner. The figures here include it.

Which alternatives are cheapest?

The job is the same on every row, at list rates: 1,000 runs of a 2 vCPU, 4 GiB sandbox for 60 seconds each, with 20 CPU-seconds of work in every run. Both Fly.io products appear, the Machine fifth and the Sprite ninth. The calculation for each row is on pricing, and it leaves out plan fees, storage, network, free credits and negotiated deals.

Cost for the same job

The calculation for Runtime, both Fly.io products and two other rivals. The Sprite is assumed to use all 4 GB for the whole minute; the Machine is a performance-2x with 4 GB in iad.

When the work fills both CPUs, busy for the whole minute, the job is $1.33 on Runtime against $3.47 on Sprites, $1.53 on Machines, $3.35 on Cloudflare and $2.76 on E2B. At 100,000 waiting runs per month, the bill is $63.89 on Runtime, $240.14 on Sprites and $152.78 on Machines.

A Sprite bills the memory it actually uses, so a job that uses 1 GB pays $0.76 there in total.

What each alternative gives a Fly.io user

1. Northflank: below a Machine's price, busy or not

$0.01667 per vCPU-hour and $0.00833 per GB-hour, allocated, puts this job at $1.11 either way. Sandboxes are services with deployment plans, in Northflank's regions or inside your own AWS, GCP or Azure account.

2. Cloudflare Sandbox: close to users everywhere

Each container has its own VM and starts near users across Cloudflare's network, and is called from a Worker on the Workers Paid plan. Active CPU is $0.072 per vCPU-hour with at least 3 GiB per vCPU. Filesystem-only snapshots, in public beta, restore saved files after a stop; memory and processes restart.

3. Morph: branching with memory

$0.05 per MCU-hour, where one MCU is 1 vCPU, 4 GB of memory or 16 GB of disk. Infinibranch clones a running machine, memory included, into hundreds of replicas, where a Machine keeps memory only through suspend.

4. Vercel Sandbox: two more regions than Machines

Active CPU at $0.128 an hour and memory at $0.0212 per GB-hour in iad1, on Firecracker, in 19 regions. Stopping keeps the filesystem; processes restart.

5. CodeSandbox SDK: big fixed sizes

A Nano VM of 2 cores and 4 GB is $0.1486 an hour, rounded up to the minute, and sizes reach 64 cores and 128 GB.

6. E2B: Firecracker with an open runtime

Allocated at $0.0504 per vCPU-hour and $0.0162 per GiB-hour. Pro, at $150 per month, allows 24-hour sessions against Hobby's one, and the Apache-2.0 runtime can be self-hosted.

7. Daytona: GPUs and Windows

The same rates as E2B, a container as the default sandbox, and GPU sandboxes and Windows machines in the US and the EU.

8. Blaxel: standby without asking

Like a Sprite, a Blaxel sandbox goes to standby on its own, in its case when connections close, and resumes in about 25 ms. Active memory costs $0.0000115 per GB-second, CPU included.

9. Modal Sandboxes: GPUs and functions

gVisor or VM isolation, with CPU billed at $0.1419 per physical core-hour on the higher of request and use, alongside Modal's functions.

10. Runloop: evaluation tooling

Devboxes, a container inside a microVM, at $0.108 per CPU-hour and $0.0252 per GB-hour plus disk, set up to evaluate models on your own workload.

How to switch from Fly.io

From Sprites, the calls map one-to-one. Sprites:

JavaScriptimport { SpritesClient } from "@fly/sprites";const client = new SpritesClient(process.env.SPRITE_TOKEN);const sprite = await client.createSprite("my-sprite");const result = await sprite.execFile("python3", ["-c", "print(sum([125, 250, 375]))"]);console.log(result.stdout);await sprite.delete();

Runtime:

TypeScriptimport { Sandbox } from "withruntime";const box = await Sandbox.create();try {  await box.files.write("/workspace/invoice.py", "print(sum([125, 250, 375]))\n");  console.log((await box.exec(["python3", "/workspace/invoice.py"], { check: true })).stdout);} finally {  await box.stop();}

A Sprite that pauses itself becomes a sandbox with idlePauseSeconds; the next request wakes it:

Pythonfrom withruntime import Sandboxsbx = Sandbox.create(idle_pause_seconds=600)sbx.update(idle_pause_seconds=1800)  # 0 turns it offsbx.stop()

From Machines, where you create one Machine per job through the Machines API, create a Runtime sandbox instead and stop it when the job ends.

Or leave it to a coding agent: the instruction in migration has it swap the calls on a branch, test on the free usage and report the monthly difference. Credit you add within 30 days of signing up is matched, up to $1,000 in total. On the isolation both platforms share, see Firecracker and microVM vs container.

Sources

Fly.io prices checked 25 October 2026.

• Cloudflare sandbox lifetime, snapshot behavior checked 25 October 2026. All rival rates were checked 25 October 2026, and the Fly.io pricing page was read again on 26 October 2026.

• Fly.io pricing

• Northflank pricing

• Together: CodeSandbox SDK

• E2B pricing

• Runloop pricing

• Morph Cloud pricing

• Blaxel pricing Facts on this page were checked on 26 October 2026.

• Cloudflare Containers pricing

• Vercel Sandbox pricing

• Modal pricing

• Daytona pricing

• Runtime pricing, speed and the Fly.io comparison