Northflank Sandboxes vs Modal Sandboxes
Answer in brief
Choose Northflank Sandboxes for teams that want sandboxes in their own cloud account (BYOC) alongside app hosting, databases and GPUs; choose Modal Sandboxes for high-concurrency and GPU-backed sandboxes — RL rollouts, evals and coding agents at scale. Northflank Sandboxes uses Cloud Hypervisor microVM isolation; Modal Sandboxes uses gVisor or VM isolation.
Northflank Sandboxes vs Modal Sandboxes at a glance
| Attribute | Northflank Sandboxes | Modal Sandboxes |
|---|---|---|
| What it is | Sandboxes on Northflank’s Kubernetes-based platform — microVMs for CPU work, gVisor for GPUs — on Northflank’s cloud or in your own cloud account. | Sandboxes on Modal’s serverless compute platform for running untrusted code at very high scale, with GPUs, snapshots and tunnels. |
| Isolation | MicroVMs on Cloud Hypervisor with their own guest kernel for CPU workloads; gVisor for GPU workloads | gVisor by default, or VMs with their own Linux kernel; GPU sandboxes use gVisor |
| Open source | No | No (Client SDK Apache-2.0) |
| Self-host / BYOC | No / Yes | No / Not documented |
| SDKs | JavaScript/TypeScript, Python | Python, JavaScript/TypeScript, Go |
| Cold start (vendor claim) | Under 1 s; sample “ready in 0.8 seconds” on a cached image (vendor claim) | Sub-second, including for large custom images (vendor claim) |
| Max session | No time limit; runs until deleted; idle sandboxes can be paused | 5 minutes default, configurable up to 24 hours; snapshots carry state beyond that |
| Persistence | Ephemeral by default; persistent and shared volumes, S3 mounts, managed databases and pause/resume | Filesystem snapshots, directory snapshots, memory snapshots (alpha) and Modal Volumes |
| GPU | Yes — L4 to B200 under gVisor (e.g. H100 $2.74/hour on Northflank Cloud) or on your own GPU nodes | Yes — Modal’s full GPU range (T4 to B300) at standard per-second rates, e.g. H100 $0.001097/s |
| Networking | Private by default; network policies for ingress/egress by FQDN and IP range; mTLS service mesh; secrets injected at egress | Outbound open by default; block all, CIDR allowlists or domain allowlists (beta), updatable at runtime; encrypted tunnels with public URLs and connect tokens |
| Pricing | Per second: $0.01667 per vCPU-hour + $0.00833 per GB-hour; BYOC $0.02083 per node vCPU-hour plus your cloud bill | Per second at sandbox (non-preemptible) rates: $0.00003942 per physical core-second (1 core = 2 vCPU) + $0.00000667 per GiB-second; GPUs at standard rates. Team plan $250/month |
| Compliance | SOC 2 Type II, HIPAA, ISO 27001 | SOC 2 on all plans; HIPAA on Enterprise |
| Best for | Teams that want sandboxes in their own cloud account (BYOC) alongside app hosting, databases and GPUs | High-concurrency and GPU-backed sandboxes — RL rollouts, evals and coding agents at scale |
Verified November 8, 2026 from each provider’s documentation. Cold-start figures are vendor claims, not our measurements.
Which should you choose?
Choose Northflank Sandboxes if…
- You need BYOC on any major cloud or bare metal
- You want GPUs and CPU sandboxes on one platform
- You also need app hosting, databases and pipelines
- You want low published per-vCPU rates
Choose Modal Sandboxes if…
- You need very high concurrency (RL, evals, batch agents)
- You need GPUs inside the sandbox
- You already use Modal for inference or training
- You want Go as well as Python and TypeScript SDKs
Both are worth piloting with your own image and region. See the full Northflank Sandboxes profile and Modal Sandboxes profile, or the complete comparison.
Frequently asked questions
Is Northflank Sandboxes or Modal Sandboxes better for AI agents?
Neither is better for every workload. Northflank Sandboxes is best for teams that want sandboxes in their own cloud account (BYOC) alongside app hosting, databases and GPUs. Modal Sandboxes is best for high-concurrency and GPU-backed sandboxes — RL rollouts, evals and coding agents at scale.
Which is open source, Northflank Sandboxes or Modal Sandboxes?
Neither is open source.
How do Northflank Sandboxes and Modal Sandboxes isolate code?
Northflank Sandboxes: MicroVMs on Cloud Hypervisor with their own guest kernel for CPU workloads; gVisor for GPU workloads. Modal Sandboxes: gVisor by default, or VMs with their own Linux kernel; GPU sandboxes use gVisor.
Sources
- northflank.com/product/sandboxes
- northflank.com/pricing
- northflank.com/docs/v1/application/sandboxes
- bleepingcomputer.com/news/security/northflank-security-breach-leads-to-abuse-of-customers-ai-api-keys/
- modal.com/use-cases/sandboxes
- modal.com/pricing
- modal.com/docs/guide/sandbox
- modal.com/docs/guide/sandbox-networking
Cite this page
Agent Sandboxes. (2026). Northflank Sandboxes vs Modal Sandboxes. agentsandboxes.org. Last reviewed November 8, 2026. https://agentsandboxes.org/compare/northflank-vs-modal/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.