Unikraft Cloud
Millisecond-start microVMs built from Dockerfiles on a modified Firecracker VMM, with stateful scale-to-zero, live forking ("branching") and checkpoints, plus a Sandbox SDK for agents. A density- and latency-focused microVM platform whose stateful forking and shielded egress suit large agent fleets, if you can work with unpublished pricing.
Overview
Unikraft Cloud (formerly at unikraft.cloud, now unikraft.com) turns a Dockerfile into a specialised microVM image and runs it on a modified Firecracker VMM, "based on Linux Foundation's Unikraft project". Its pitch is density and latency: "100K+" microVMs per server and sub-10 ms cold starts, scale-to-zero and resume, all vendor claims. You deploy with the unikraft CLI, the REST API, or SDKs for JavaScript/TypeScript (@unikraft/cloud, which includes a Sandbox class with exec, writeFile and PTY-style control), Python (unikraft-cloud, async) and Go. Sandboxes sit behind a dedicated "network shield" microVM that filters egress and injects credentials so sandboxed code never sees API keys.
State features are the differentiator: instances scale to zero statefully, templates are memory snapshots you clone from, branching forks a running sandbox (memory and volume) in milliseconds for sub-agents, and checkpoints give a rewindable history; live migration moves running VMs between hosts. GPU support exists only as an enterprise preview on QEMU-backed full VMs, which lose branching and checkpointing. Pricing is not published (hosted, dedicated and on-prem/BYOC options, including running as nodes in EKS, GKE or AKS). The company reports SOC 2 Type II and HIPAA compliance.
Notable
- Vendor claims "<10ms" cold start and "100K+" microVMs per server; Browser Use is cited as a customer with "8ms cold start times".
- GPU support is "currently only available as a preview for enterprise customers" and limited to one GPU per
fullinstance. - Deployment options span hosted, dedicated hosted, BYOC and on-prem, including bare metal and VMs on AWS EC2, GCP Compute Engine and Azure.
Unikraft Cloud specifications
| Attribute | Details |
|---|---|
| Isolation | Hardware-isolated microVM per instance with its own kernel, run on a "Modified Firecracker VMM" (KVM); sandbox egress passes through a separate "network shield" microVM that holds credentials |
| Deployment | Hosted platform · BYOC available · Self-hostable |
| Open source | No |
| SDKs and interfaces | JavaScript/TypeScript, Python, Go, CLI, REST API |
| Cold start (vendor claim) | Vendor claims "<10ms" cold start and scale-to-zero for all workloads, "branch & restore in < 10 ms", and "Fork a live virtual computer in 10 milliseconds"; the how-it-works page says apps are pre-initialised and snapshotted so a request to a dead-cold instance is answered "within a single round trip" |
| Max session length | Not documented |
| Persistence | Stateful scale-to-zero (standby instances resume with memory intact); templates are snapshotted instances that preserve memory, open files and caches; branching clones a running sandbox including memory and volume state; checkpoints keep a history you can rewind to; block volumes; live migration between servers; "autokill" terminates long-running sandboxes |
| GPU | Preview for enterprise customers only: requires the full (QEMU) instance type, at most one GPU per instance and you cannot choose which (example model NVIDIA Tesla T4); full VMs do not support branching or checkpointing |
| Networking | Each instance gets a private IP and .internal FQDN; service groups expose a public domain <name>.<metro>.unikraft.app; sandbox traffic is filtered by the network-shield microVM so "nothing reaches the internet directly" |
| Pricing | Contact sales — the pricing page lists Hosted, Dedicated Hosted and On-Prem options without figures |
| Free tier | Free account sign-up ("Create a free account"); no credit or allowance figures published |
| Compliance | SOC 2 Type II; HIPAA-compliant; third-party penetration tested (trust.unikraft.com) |
| Regions | Default metros: Dallas, Frankfurt, San Francisco, Singapore, Washington DC; around two dozen further metros available on request |
Facts from Unikraft Cloud’s public documentation, verified November 9, 2026. Performance numbers are vendor claims.
Strengths and trade-offs
Strengths
- You need very high sandbox density and millisecond resume from idle
- You want to fork a running agent environment (memory included) for parallel sub-agents
- You need a credential-holding egress proxy so sandboxed code never sees secrets
- You run on your own hardware or cloud and want the same stack on-prem or BYOC
Trade-offs
- No public pricing; hosted plans are contact-sales
- GPU support is an enterprise preview on a different (QEMU) instance type without branching or checkpoints
- The platform itself is proprietary; only the underlying Unikraft kernel project is open source
- Maximum instance sizes and session limits are not documented
Good fit for: Agent fleets that need thousands of sandboxes per server, millisecond stateful wake-ups and live forking of running environments.
How Unikraft Cloud compares
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| Unikraft Cloud | microVM (modified Firecracker) | No | Yes / Yes | <10 ms (claimed) | Not documented | Yes / Yes | Yes | JavaScript/TypeScript, Python, Go, CLI, REST API |
| Fly Machines | Firecracker microVM | No | No / No | <1 s start (claimed) | Not documented | Yes / Yes | Not documented | Go, CLI, REST API |
| E2B | Firecracker microVM | Yes | Yes / Yes | Not documented | 1 h / 24 h (Pro) | Yes / Yes | No | Python, JavaScript/TypeScript |
| Morph Cloud | VM | No | No / Not documented | <250 ms (restore) | Configurable | Yes / Yes | Not documented | Python, TypeScript |
| AWS Lambda MicroVMs | Firecracker microVM | No | No / No | sub-second to seconds (claimed) | 8 h | Yes / Yes | No | Python, JavaScript/TypeScript, PHP, CLI, REST API |
| Blaxel | MicroVM | No | No / Yes | <25 ms resume | Unlimited (standby) | Yes / Yes | Not documented | TypeScript, Python, Go |
| Modal Sandboxes | gVisor or VM | No | No / Not documented | <1 s | Up to 24 h | Yes / Yes | Yes | Python, JavaScript/TypeScript, Go |
Frequently asked questions
What is Unikraft Cloud?
How does Unikraft Cloud isolate code?
Is Unikraft Cloud open source?
How much does Unikraft Cloud cost?
What are the alternatives to Unikraft Cloud?
Sources
Cite this page
Agent Sandboxes. (2026). Unikraft Cloud. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/sandboxes/unikraft-cloud/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.