Which is better, Modal or Northflank?
It depends on how busy the work is and where it must run. For agents that mostly wait on a model, Runtime has the lowest bill: $0.64 for 1,000 one-minute runs, against $1.11 on Northflank and $3.97 on Modal. Pause also keeps memory and processes. Pick Modal if you already run Modal functions, web endpoints and scheduled jobs, and want sandboxes beside them, with GPUs. Pick Northflank for CPU-bound work that keeps every core busy, for GPUs, or for sandboxes in your own cloud account.
At a glance
| Modal Sandboxes | Northflank | Runtime | |
|---|---|---|---|
| Isolation | gVisor, a user-space kernel that intercepts system calls | microVMs for CPU workloads, gVisor for GPU workloads | Firecracker microVM, own kernel |
| CPU | $0.1419 per physical core-hour (2 vCPUs), request or use | $0.01667 per allocated vCPU-hour | $0.025 per vCPU-hour of measured CPU, with a small floor |
| Memory | $0.0240 per GiB-hour, request or use | $0.00833 per GB-hour | $0.0075 per reserved GiB-hour |
| Plan fee | Starter $0 with $30 a month of compute; Team $250 a month | None published for compute | None; prepaid credit from $10 |
| Free start | $30 of compute a month on Starter | 2 services, 2 jobs and 1 database free | 100 free hours of a 1 GB machine in the first 30 days, no card |
| Session length | Up to 24 hours; snapshots carry state beyond that | No time limit, seconds to weeks | No time limit: runs while it works, pauses itself after 300 seconds idle |
| What you create | A Sandbox, attached to a Modal App | A service with a deployment plan | A sandbox, in one call |
Why is Northflank so much cheaper than Modal?
Both bill what a sandbox holds for as long as it runs, so the rates decide. Northflank's are lower on both meters. A vCPU costs $0.071 an hour on Modal (half of a $0.1419 physical core), against $0.01667 on Northflank, about a quarter as much. Memory costs $0.0240 per GiB-hour on Modal, against $0.00833 per GB-hour on Northflank. Put together, a 2 vCPU, 4 GiB sandbox costs about $0.24 an hour on Modal and about $0.067 on Northflank. Modal is about 3.6 times the price whether the code is busy or waiting.
Runtime charges for measured CPU instead. For an agent that waits on a model, that makes it cheaper than both.
Which one has GPUs, longer sessions or your own cloud?
- GPUs: both. Modal sandboxes can use GPUs. Northflank rents H100s and other GPUs, at $2.74 an hour for an H100 80 GB. It uses gVisor for GPU workloads.
- Session length: a Modal sandbox runs for up to 24 hours, and a snapshot carries its state into a new one. Northflank states no time limit.
- Your own cloud: Northflank runs sandboxes in its own regions or inside your VPC on AWS, GCP, Azure or Oracle.
A Runtime sandbox has no time limit. It runs while it works, and a paid one
can be made persistent to run even while idle. A sandbox that goes quiet can pause
itself and wake on the next request, with its memory and processes intact:
TypeScriptimport { Sandbox } from "withruntime";const dev = await Sandbox.getOrCreate("agent-worker", { idlePauseSeconds: 600 });console.log((await dev.exec("uptime", { check: true })).stdout);// Ten quiet minutes later it pauses; the next exec wakes it where it left off.Cost for the same job
1,000 runs of a 2 vCPU sandbox (one physical core on Modal) with 4 GiB, or 4 GB on Northflank. Each run lasts 60 seconds and keeps the CPU busy for 20 CPU-seconds: an agent that mostly waits for a model.
- CPU
- 1,000 × 60 s × 1 core × $0.00003942
- $2.37
- Memory
- 1,000 × 60 s × 4 × $0.00000667
- $1.60
- CPU
- 1,000 × 60 s / 3,600 × 2 × $0.01667
- $0.556
- Memory
- 1,000 × 60 s / 3,600 × 4 × $0.00833
- $0.555
- CPU
- 1,000 × 20 s / 3,600 × $0.025
- $0.14
- Memory
- 1,000 × 60 s / 3,600 × 4 × $0.0075
- $0.50
At 100,000 runs a month, the cost is $396.60 on Modal, $111.10 on Northflank, and $63.89 on Runtime. With both CPUs busy for the whole minute, the cost is $1.33 on Runtime, against $3.97 on Modal and $1.11 on Northflank. Northflank is the cheapest of the three for work that keeps every CPU busy. Runtime costs less than Northflank until a run keeps its CPUs busy for about 88 of its 120 CPU-seconds. Plan fees, storage, network and free allowances are left out.
Which one to pick
- Pick Modal if you already run Modal functions, web endpoints and scheduled jobs and want sandboxes beside them in the same SDK, with GPUs.
- Pick Northflank for CPU-bound work that keeps every core busy, or sandboxes in your own cloud account.
- Pick Runtime for agents that spend most of their time waiting. Measured CPU makes it 42% cheaper than Northflank and 84% cheaper than Modal. Pause keeps memory and running processes while you have credit.
Runtime Cloud
Runtime runs the same job for 84% less than Modal and 42% less than Northflank. 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox cost $3.97 on Modal, $1.11 on Northflank, and $0.64 on Runtime, for an agent that mostly waits on a model. Runtime bills the CPU the code uses rather than the CPUs it holds. It creates a sandbox in one call, with no App or service. Rates were checked 25 October 2026.
Sign in with npx withruntime login to run on the free usage. See the migration guide for moving existing code.
Switch from either one
From Modal, the calls map one to one: modal.Sandbox.create(app=...) becomes
Sandbox.create(), sb.exec(*args) becomes exec, Sandbox.from_name
becomes Sandbox.getOrCreate(name), and idle_timeout becomes
idlePauseSeconds. From Northflank, a sandbox is no longer a service. Replace
the service and its deployment plan with Sandbox.create(), and map the
commands, files and teardown with the table in
migration.
Or give your coding agent the instruction in migration. It switches the project on a branch, tests it on the free usage, and reports the monthly saving. From Modal, credit you add within 30 days of signing up is matched, up to $1,000 in total. The full side-by-sides are Runtime vs Modal and Runtime vs Northflank. For the isolation question, see Firecracker vs gVisor.
Sources
Northflank's sandboxes page was rechecked 26 October 2026. The rest were checked 25 October 2026.
- Modal pricing, Modal resources and billing, Modal Sandboxes, Modal security
- Northflank pricing, Northflank sandboxes, Sandboxes on Northflank
- Runtime pricing
Facts on this page were checked on 26 October 2026.