Runtime runs each agent in a Firecracker microVM with its own Linux kernel and charges for measured CPU, so while the agent waits on its model it pays for memory and a small CPU floor, not for idle vCPUs. A month of 1,000 one-minute agent runs on a 2 vCPU, 4 GiB sandbox costs $0.64 on Runtime and $1.11 to $5.33 on the fourteen other providers, at their published rates checked 23 September to 2 October 2026. A new sandbox runs its first command 221 ms after the create request, timed on our servers. Another provider fits better if you need GPUs, self-hosting or many regions: each is named below.
Which sandbox is best for each need?
| If you need | Pick | Why |
|---|---|---|
| The lowest bill for agents that wait on a model | Runtime | Measured CPU, never below a twentieth of a vCPU; $0.64 for the job below |
| CPUs busy the whole run | Northflank | Low allocated rates: $1.11 against Runtime's $1.33 |
| GPUs in the sandbox | Modal or Daytona | Both sell GPU sandboxes; Runtime runs on CPUs |
| A sandbox you host yourself | E2B | Its runtime is open source under Apache-2.0 |
| Many regions | Vercel Sandbox or Fly.io | Vercel lists 19 regions and Fly Machines 18; Runtime runs in one US region |
| An app already on Workers | Cloudflare Sandbox | It runs on Cloudflare's network, beside the Worker |
| Hundreds of copies of one running machine | Morph | Infinibranch copies a running machine, memory included |
| Public benchmarks ready to run | Runloop | SWE-Bench and other benchmarks come set up |
What does each sandbox cost for the same agent job?
Every row prices one job at list rates: 1,000 runs, each 60 seconds on a 2 vCPU, 4 GiB sandbox, with 20 CPU-seconds of real work per run while the rest waits on a model. Plan fees, storage, network and credits stay out of it; the arithmetic is on pricing.
| # | Provider | Isolation | CPU billed on | 1,000 runs |
|---|---|---|---|---|
| 1 | Runtime | Firecracker microVM, own kernel | Measured CPU, with a small floor | $0.64 |
| 2 | Northflank | microVMs for CPU work, gVisor for GPU work | Allocated vCPUs | $1.11 |
| 3 | Cloudflare Sandbox (2 vCPU, 6 GiB, 12 GB disk) | A container in its own VM | Active CPU | $1.35 |
| 4 | Prime Sandboxes (5 GiB disk) | microVM, own guest kernel | Allocated vCPUs while running | $1.52 |
| 5 | Fly Machines, performance-2x with 4 GB |
Firecracker microVM | The machine's size while started | $1.53 |
| 6 | Morph, 2 MCUs | Full virtual machines | The machine's size in MCUs | $1.67 |
| 7 | Vercel Sandbox, iad1 (4 GB) |
Firecracker microVM, own kernel | Active CPU | $2.12 |
| 8 | Freestyle (32 GiB disk) | Full Linux virtual machines | Allocated vCPUs | $2.25 |
| 9 | Fly Sprites (4 GB in use) | Firecracker microVM | Measured CPU | $2.40 |
| 10 | CodeSandbox SDK, a Nano VM | Firecracker microVM | The VM's size, by the minute rounded up | $2.48 |
| 11 | E2B | Firecracker microVM, own kernel | Allocated vCPUs | $2.76 |
| 12 | Daytona | Containers by default; VM class separate | Allocated vCPUs | $2.76 |
| 13 | Blaxel (4 GB) | Lightweight virtual machines | Included with memory, active time | $3.45 |
| 14 | Modal Sandboxes (1 physical core) | gVisor, a user-space kernel | Requested or used, whichever is higher | $3.97 |
| 15 | AWS Lambda MicroVMs, Arm | Firecracker microVM | Baseline vCPUs while running | $4.20 |
| 16 | Runloop, a MEDIUM devbox |
microVM, with a container inside | Allocated CPUs while running | $5.33 |
The order follows the meter. A provider that bills allocated vCPUs charges for all 60 seconds of both CPUs, though the agent worked for 20 CPU-seconds; one that bills measured or active CPU charges for the work. At 100,000 runs a month the job is $63.89 on Runtime, $111.10 on Northflank and $276.00 on E2B. Your own job's shape: the sandbox cost calculator.
Which sandbox starts fastest?
Runtime's figure is measured; the others are what each provider publishes, which rarely says where it was timed from or at what percentile:
| Provider | A new sandbox |
|---|---|
| Runtime | 221 ms to the first command's result, on the server (median) |
| Daytona | under 90 ms, from code to execution |
| E2B | about 150 ms |
| Modal | under one second |
| Blaxel | under one second |
| Cloudflare Sandbox | often 1 to 3 seconds |
For an agent, the wake matters as much as the create: a paused Runtime sandbox runs its next command 153 ms after the request, with its memory and processes as they were. Every step, its percentiles and each provider's source are in speed.
What should an AI agent sandbox have?
- Its own kernel. Agent code is untrusted code. A container shares the host's kernel, so a kernel bug is a way out; a microVM boots its own.
- A meter that matches agent work. Most of an agent's minute is spent waiting on a model. Allocated billing charges for that wait; measured CPU does not.
- Pause that keeps memory. An agent between a user's turns should cost storage, not compute, and come back with its processes running. Runtime pauses a sandbox by itself after 60 seconds with nothing happening.
- No session limit. A Runtime sandbox runs while it works, on prepaid credit from $10 with no plan fee.
- Control from outside the sandbox. Network rules the host enforces, and secrets the sandbox never sees, so a prompt injection cannot widen either.
- Room to grow. Up to 16 vCPUs and 64 GiB per sandbox, 100 at once on a paid account.
The full checklist, with where Runtime stands on each point, is in how to choose a sandbox for AI agents.
When is Runtime not the best choice?
- GPUs. Runtime runs on CPUs. Modal and Daytona sell GPU sandboxes.
- Self-hosting. Runtime is a hosted service. E2B publishes its runtime under Apache-2.0, to run on your own machines.
- Regions. Runtime runs in one US region. Vercel Sandbox lists 19 regions and Fly Machines 18.
- CPUs busy every second. When both CPUs work the whole minute, Northflank costs $1.11 for the job and Runtime $1.33.
How do I try Runtime?
100 free hours of a 1 GB machine come every month, no card. One call starts a sandbox:
TypeScriptimport { Sandbox } from "withruntime";await using sbx = await Sandbox.create();await sbx.exec("git clone --depth 1 https://github.com/psf/requests /workspace/requests", { check: true,});console.log((await sbx.exec("cd /workspace/requests && git log -1 --oneline")).stdout);Code written for E2B, Daytona, Vercel Sandbox or Blaxel runs after one changed import (migration). Leaving a particular provider? Its alternatives page ranks the rest from its side: E2B, Daytona, Modal or Vercel Sandbox. The same jobs, dated and downloadable, are in the agent sandbox price index.
Sources
Rival rates checked 23 September to 2 October 2026; their speed claims checked 28 September 2026.
- Each provider's published rates, as the pricing guide lists them with links
- Each provider's published start times, as speed lists them with links
- E2B, Modal and Vercel Sandbox comparisons: self-hosting, GPUs and regions
- E2B alternatives: what each provider adds, with its pricing page
- Runtime's own figures: speed, pricing and limits