# Modal vs CodeSandbox: pricing, isolation and limits Modal runs sandboxes under gVisor, billed per second on the request; CodeSandbox runs Firecracker VMs in fixed sizes, billed by the minute. **Runtime charges 84% less than Modal and 74% less than CodeSandbox for one job, and it is also the only one of the three that bills by use.** 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox cost $3.97 on Modal, $2.48 on CodeSandbox and $0.64 on Runtime. Modal and CodeSandbox charge for the whole machine as long as it is up. Runtime counts the CPU the code spends, per second, inside a Firecracker microVM with its own kernel. Rates checked 23 September 2026. ## At a glance On Modal, 2 vCPUs are one physical core, its billing unit. CodeSandbox's rates are from Together's documentation of the CodeSandbox SDK; CodeSandbox is a Together company. | | Modal Sandboxes | CodeSandbox SDK | Runtime | | ------------- | --------------------------------------------------------- | --------------------------------------------------- | -------------------------------------------------------- | | Isolation | gVisor, a user-space kernel that intercepts system calls | Firecracker microVM | Firecracker microVM, own kernel | | CPU | $0.1419 per physical core-hour (2 vCPUs), request or use | By VM size: Nano (2 cores, 4 GB) is $0.1486 an hour | $0.025 per vCPU-hour of measured CPU, with a small floor | | Memory | $0.0240 per GiB-hour, request or use | Inside the VM size | $0.0075 per reserved GiB-hour | | Billing unit | Per second | Per minute, rounded up | Per second | | Shapes | CPU and memory requested per sandbox | Fixed sizes, up to 64 cores and 128 GB | vCPUs and memory chosen per sandbox | | Plan fee | Starter $0 with $30 a month of compute; Team $250 a month | Build free, 10 VMs at once; Scale $170 a month | None; prepaid credit from $10 | | At once | 100 containers on Starter; 5,000 on Team | 10 VMs on Build; 250 on Scale | 8 on the trial; 100 to start on a paid account | | Keeping state | Filesystem snapshots; up to 24 hours a sandbox | Memory snapshot and restore | Pause, snapshots and forks with memory and processes | ## Which is cheaper for short runs? It turns on how long each run lasts. Modal bills by the second, but at $0.1419 a core-hour plus $0.0240 a GiB-hour, $0.2379 an hour for this size. CodeSandbox's Nano VM costs $0.1486 an hour, but each run is rounded up to a whole minute. | 1,000 runs, 2 vCPU, 4 GiB, 20 CPU-seconds each | Modal | CodeSandbox | Runtime | | ---------------------------------------------- | ----: | ----------: | ------: | | 20-second runs | $1.32 | $2.48 | $0.31 | | 40-second runs | $2.64 | $2.48 | $0.47 | | 60-second runs | $3.97 | $2.48 | $0.64 | Modal is cheaper for runs under about 38 seconds, and CodeSandbox for anything longer up to a minute. Runtime bills by the second with no one-minute minimum, and counts CPU as measured, so it is the cheapest at every length. ## Cost for the same job The 60-second row in detail. Modal runs the 2 vCPU, 4 GiB sandbox on one physical core; CodeSandbox uses a Nano VM at 10 credits an hour, $0.01486 a credit. Each of the 1,000 runs lasts 60 seconds and does 20 CPU-seconds of work. ``` Modal CPU 1,000 × 60 s × 1 core × $0.00003942 = $2.37 Memory 1,000 × 60 s × 4 × $0.00000667 = $1.60 Total $3.97 CodeSandbox Size 1,000 × 60 s / 3,600 × $0.1486 = $2.48 Runtime CPU 1,000 × 20 s / 3,600 × $0.025 = $0.14 Memory 1,000 × 60 s / 3,600 × 4 × $0.0075 = $0.50 Total $0.64 ``` A month of 100,000 runs: $396.60 on Modal, $247.67 on CodeSandbox, $63.89 on Runtime. The busy variant, both CPUs busy for the whole minute, costs $1.33 on Runtime, $3.97 on Modal and $2.48 on CodeSandbox, the rivals unchanged since both already charged for the full machine. Plan fees, storage, network and free credit are outside the figures. ## User-space kernel or microVM? Modal puts each sandbox under gVisor, which catches the sandbox's system calls and answers them from a kernel written to run in user space. CodeSandbox and Runtime both boot each sandbox as a Firecracker microVM, with its own Linux kernel behind hardware virtualization. For the trade-offs, see [Firecracker vs gVisor](/compare/firecracker-vs-gvisor) and [what is a microVM?](/glossary/microvm). ## Which one to pick - **Modal** fits GPU sandboxes, large numbers of very short runs where per-second billing pays off, and teams already running Modal functions and scheduled jobs. - **CodeSandbox** fits jobs that need a very large fixed machine, up to 64 cores and 128 GB, or a fleet of 250 VMs at once on Scale. - **Runtime** fits agent sandboxes: a microVM each, at a sixth of Modal's price and about a quarter of CodeSandbox's, measured CPU by the second, 100 at once to start and no plan fee. ## Porting from each Modal's calls translate one for one, and no App is required: `modal.Sandbox.create(app=...)` is `Sandbox.create()`, `sb.exec(*args)` is `exec`, `Sandbox.from_name` is `Sandbox.getOrCreate(name)`. CodeSandbox's create, command, file read and write, and shutdown calls each have a single Runtime counterpart in the [migration table](/docs/migrate#map-the-calls); instead of picking a VM tier, you set vCPUs and memory per sandbox. ```python from withruntime import Sandbox with Sandbox.create(funding="trial") as box: print(box.exec("python3 -c 'print(6 * 7)'", check=True).stdout) ``` `npx withruntime compare --from codesandbox` reprices the sandboxes you ran at CodeSandbox's rates next to Runtime's. For Modal users, `npx withruntime switch --from modal` before the first top-up matches it with credit, up to $100. A coding agent can do either port from the one instruction in [migration](/docs/migrate), working on a branch and testing on the free trial. See [Runtime vs Modal](/docs/modal-sandbox-alternative) and [Runtime vs CodeSandbox](/docs/codesandbox-alternative). ## Sources Modal pricing and Modal Sandboxes pages rechecked 25 September 2026; the rest checked 23 September 2026. - [Modal pricing](https://modal.com/pricing), [Modal resources and billing](https://modal.com/docs/guide/resources), [Modal Sandboxes](https://modal.com/docs/guide/sandbox), [Modal security](https://modal.com/docs/guide/security) - [Together Code Sandbox](https://docs.together.ai/docs/together-code-sandbox), [CodeSandbox SDK pricing](https://codesandbox.io/docs/sdk/pricing) - Runtime [pricing](/docs/pricing) and [security](/docs/security) Facts on this page were checked on 25 September 2026.