AWS Lambda MicroVMs alternative: agent sandboxes in the EU

On 23 June 2026, AWS shipped if you're an EU company that wants execution, snapshots and logs inside one EU legal entity, you want to pay for CPU you actually burned rather than CPU you reserved, and your sandboxes are small and numerous rather than huge.

The same primitive

Both products run on Firecracker. AWS says so on the docs page - "Lambda MicroVMs deliver these core capabilities through Firecracker virtualization" - and so do we. Each sandbox is a hardware-isolated VM with its own kernel and rootfs, not a container sharing the host kernel. That distinction matters exactly when an LLM is writing shell commands you haven't read yet.

The lifecycle is the same too. Create, exec, read and write files, pause, resume, terminate. Here's ours:

from orkestr import Sandbox



with Sandbox.create(template="python-3.12") as sbx:

    sbx.files.write("/workspace/main.py", "print(sum(range(1_000_000)))")

    result = sbx.exec("python /workspace/main.py")

    print(result.stdout)   # 499999500000

Same primitive, different jurisdiction and different economics. Everything below follows from that.

Where AWS wins

Ceiling. Lambda MicroVMs go to 16 vCPU / 32 GB / 32 GB of disk, with 4x vertical burst above your configured baseline. Our largest sandbox is 4 vCPU / 8 GB. If one sandbox has to compile a large C++ tree or hold a 20 GB dataframe in memory, we're the wrong answer and you can stop reading here.

Ecosystem. IAM, VPC attachment, S3, CloudWatch - if your agent needs to reach private AWS resources, a Lambda MicroVM sits inside your account and ours doesn't. AWS even published a guide for : an ext4 volume mounted at /persist, checkpointed to EU object storage, that survives termination and re-attaches to a completely different sandbox later. An agent picks up the workspace it left behind last week. The caveat: the object-storage copy is only as fresh as the last checkpoint, so losing a box can lose writes since the last upload.

The CPU you don't burn is free. Lambda MicroVMs bill the baseline rate for the whole time the VM is running, and charge extra only for burst above baseline. We split the bill in two and meter each per second: CPU on real on-CPU time, RAM on memory actually held. Your sandbox's provisioned size is never multiplied by a rate anywhere in our billing code.

That matters because of what an agent session does with an hour. It runs a command for ninety seconds, then sits there while the model thinks, then runs another. The CPU is idle most of the wall clock - and idle CPU costs you nothing:

One hour on a 1 vCPU / 1 GiB agent sandbox, billed two ways



                0              15             30             45             60 min

                |              |              |              |              |

 sandbox        ###........###............####..............###.............

                # = running a command      . = idle, waiting on the model

                13 min of real work. The other 47 min the CPU sits idle.



 AWS Lambda     ############################################################   ~$0.155

 MicroVM        baseline rate, charged for all 60 minutes                      per hour,

                Running is running. Idle costs the same as work.               idle or not



 orkestr        two meters, both per second

   CPU          ###........###............####..............###.............   EUR 0.010

                charged on the same four bursts, nothing in between            13 min billed

   RAM          ############################################################   EUR 0.015

                held the whole hour, so charged the whole hour                 60 min billed

                                                                              ------------

                                                                               ~EUR 0.025

                                                                               per hour, all in

Lambda bills the baseline straight through the idle gaps. We bill CPU only when it runs - but the RAM meter keeps ticking, and on an idle sandbox that's most of what you pay.

Read that bottom row carefully, because the honest version is less flattering than the pitch. Idle CPU really is free: 13 minutes of work bills 13 minutes of CPU, not 60. RAM is a different story. We meter the memory the guest is actually holding, and a VM that has touched its GiB goes on holding it whether it's working or not, so the RAM meter runs at close to full rate for the entire hour. In this example that's €0.015 of a €0.025 bill - the majority of what you pay for an idle sandbox is RAM, and no amount of doing nothing makes it go away.

It's still 6x cheaper than the same hour on Lambda. It is not "an idle sandbox is nearly free," and you'd have found that out on your first invoice.

Idle isn't the exception in an agent workload. It's most of the session.

Building an image. On Lambda you package code plus a Dockerfile into a zip, upload it to S3, call the API to build an image, and wait a couple of minutes. Ours is a list of shell steps:

from orkestr import Template



Template.create(

    name="agent-py",

    base_template="python-3.12",

    recipe=[

        "apt-get update && apt-get install -y ripgrep",

        "pip install pandas duckdb",

    ],

)

The root filesystem is writable at runtime too, so apt-get install inside a live sandbox just works. (It lands in a RAM-backed overlay, so it counts against the VM's memory and vanishes on terminate. That's the tradeoff.)

The numbers, side by side

AWS rates are from the Lambda price list for eu-west-1; ours are the published and an EU alternative to Vercel Sandbox. Where they're better, we say so there too.

FAQ

Which regions do Lambda MicroVMs run in?

US East (N. Virginia, Ohio), US West (Oregon), Europe (Ireland) and Asia Pacific (Tokyo) at launch. Ireland is currently the only European one. orkestr sandboxes run in Germany, Finland and France.

Is running agent code on Lambda in Ireland a GDPR problem?

No. Ireland is in the EU and the EU-US Data Privacy Framework adequacy decision currently stands, so this is legal and compliant. The narrower concern - the reason some EU buyers still rule it out - is that the US CLOUD Act reaches data held by a US company regardless of which region it sits in. That's a question about the operator, not about the country the disk is in.

What's the real difference between Lambda MicroVMs and Lambda functions?

Functions are stateless handlers: 15-minute ceiling, frozen between invocations, no way to address a specific execution environment. MicroVMs are addressable machines you launch, suspend and resume, with a persistent disk while they live. They're different products that happen to share an isolation technology.

Can I run untrusted, AI-generated code in an orkestr sandbox?

That's what it's for. Every sandbox is its own VM with its own kernel, network egress defaults to off, and you can pin a per-sandbox allowlist of up to 50 domains when you do need it out.

How long can a sandbox live?

Up to 24 hours running. Paused sandboxes keep their memory and disk snapshot for 7 days on the free tier, 30 days with a card on file.