Which is better, Modal or Blaxel?
It depends on whether your sandboxes need GPUs, instant resume or a huge fleet. For an agent that spends most of a run waiting on a model, Runtime costs the least: $0.64 for 1,000 one-minute runs, against $3.45 on Blaxel and $3.97 on Modal. Runtime bills CPU by use within a run, and pause keeps memory and processes. Pick Modal for GPUs, or for sandboxes in the same SDK as your Modal functions and scheduled jobs. Pick Blaxel for a resume in milliseconds, or for a fleet past 100,000 sandboxes running at the same time.
At a glance
Modal's CPU unit is the physical core, equal to two vCPUs.
| Modal Sandboxes | Blaxel | Runtime | |
|---|---|---|---|
| Isolation | gVisor, a user-space kernel that intercepts system calls | Lightweight virtual machines | Firecracker microVM, own kernel |
| CPU | $0.1419 per physical core-hour (2 vCPUs), request or use | Included with memory; 8 GB gets 4 cores | $0.025 per vCPU-hour of measured CPU, with a small floor |
| Memory | $0.0240 per GiB-hour, request or use | $0.0000115 per GB-second of active time ($0.0414/h) | $0.0075 per reserved GiB-hour |
| When idle | Billed until timeout or idle_timeout ends it |
Standby about 15 seconds after connections close | Pause on request or after an idle time you set |
| Keeping state | Filesystem snapshots | Standby snapshot, $0.20 per GB-month | Paused storage with memory, $0.08 per GB-month |
| Resume | A new sandbox from a snapshot | About 25 ms from standby | Wakes with files, memory and processes |
| At once | 100 containers on Starter; 5,000 on Team | 10 sandboxes on Tier 0; over 100,000 on the top tier | 4 without credit; 100 paid |
| Plan fee | Starter $0 with $30 a month of compute; Team $250 a month | None; tiers grow with credit added | None; prepaid credit from $10 |
| Free start | $30 of compute a month on Starter | Up to $200 of credit | 100 free hours of a 1 GB machine in the first 30 days, no card |
What does an idle sandbox cost?
This is the widest gap between the two rivals.
A Modal sandbox bills its requested core and memory for as long as it runs,
whether its code is working or waiting. It runs until its timeout, which is 5 minutes
by default and up to 24 hours, or until idle_timeout ends it. State that
must outlive it goes into a filesystem snapshot for the next sandbox.
A Blaxel sandbox goes to standby by itself about 15 seconds after its last connection closes. Standby costs nothing for compute. It costs only $0.20 per GB a month for the snapshot, and the sandbox resumes in about 25 ms.
A Runtime sandbox pauses when you call pause(), or after the
idlePauseSeconds you set. It keeps its files, memory and running processes
while you have credit, at $0.08 per GB a month. A request to a paused sandbox wakes
it. While it runs, waiting is cheap too: CPU is billed as measured, with a
floor of a twentieth of a vCPU.
TypeScriptimport { Sandbox } from "withruntime";const sbx = await Sandbox.create({ timeoutSeconds: 600 });await sbx.exec("echo state > /workspace/state.txt");await sbx.pause(); // memory and files are kept; compute billing stops// ... later, even from another process:const again = await Sandbox.connect(sbx.id);await again.wake({ timeoutSeconds: 1200 });await again.extend(600); // moves its time limit ten minutes onawait again.stop();Cost for the same job
The job: 1,000 runs, 60 seconds each, on 2 vCPU and 4 GiB (a single physical core on Modal, 4 GB on Blaxel), with 20 CPU-seconds of real work per run.
- CPU
- 1,000 × 60 s × 1 core × $0.00003942
- $2.37
- Memory
- 1,000 × 60 s × 4 × $0.00000667
- $1.60
- Memory
- 1,000 × 75 s × 4 × $0.0000115
- $3.45
- 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, Modal bills $396.60, Blaxel $345.00, and Runtime $63.89. With both CPUs busy for the whole minute, the job costs $1.33 on Runtime, $3.97 on Modal, and $3.45 on Blaxel. Blaxel is priced as if standby began the instant each run finished. Plan fees, snapshots, network and free credit are excluded.
Inside a run, neither rival's price responds to load. Modal charges the request, and Blaxel charges memory with CPU folded in. Blaxel saves money only between runs, through standby.
Which one to pick
- Modal, if the sandboxes need GPUs or should live in the same SDK as your Modal functions, web endpoints and scheduled jobs.
- Blaxel, if sandboxes must resume in milliseconds, or the fleet runs past 100,000 sandboxes at the same time.
- Runtime, if you want a microVM per sandbox at 84% below Modal's price and 81% below Blaxel's. CPU is billed as used within each run, and the pause holds memory and processes while you have credit.
Runtime Cloud
Between runs, Blaxel is cheap and Modal is not. Within a run, only Runtime bills by use. That puts it 84% below Modal and 81% below Blaxel. 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox cost $3.97 on Modal, $3.45 on Blaxel, and $0.64 on Runtime. Runtime charges measured CPU plus memory at $0.0075 a GiB-hour, inside a Firecracker microVM with its own kernel. Rates were checked 25 October 2026.
Sign in with npx withruntime login to try it on the free usage. Follow the migration guide to move existing code.
Moving to Runtime
Modal code ports one call at a time and drops the App:
modal.Sandbox.create(app=...) is Sandbox.create(), sb.exec(*args) is
exec, and idle_timeout is idlePauseSeconds. Blaxel code keeps running
after one import: withruntime/blaxel for @blaxel/core, and
withruntime.blaxel for blaxel.core in Python. Standby is replaced by
automatic wake, which is on by default. Everything else is in the
migration table.
npx withruntime compare --from blaxel shows what your Blaxel sandboxes
would have cost at Runtime's rates. Credit you add within 30 days of signing up is matched, up to $1,000 in total. A coding
agent can do the port from the instruction in migration,
on a branch, without credit. See
Runtime vs Modal and
Runtime vs Blaxel.
Sources
Modal rates were checked 25 October 2026, and its pricing and Sandboxes pages were rechecked 26 October 2026. Blaxel rates were checked 25 October 2026, with its pricing page and sandbox documentation.
- Modal pricing, Modal resources and billing, Modal Sandboxes, Modal security
- Blaxel pricing, Blaxel sandboxes
- Runtime pricing
Facts on this page were checked on 26 October 2026.