E2B vs Cloudflare Sandbox: pricing, isolation and limits

E2B is a microVM API billed on allocated CPU; Cloudflare runs a container in a VM from a Worker, billed on active CPU.

On a model-bound agent job Runtime costs 77% less than E2B and 53% less than Cloudflare, with no Worker and no plan to join. 1,000 one-minute runs at 2 vCPU are $2.76 on E2B, $1.35 on Cloudflare and $0.64 on Runtime. Like Cloudflare, Runtime charges for CPU in use, but at about a third of Cloudflare's rate, and memory is whatever size the job needs. Rates checked 23 September 2026.

At a glance

The Cloudflare figures are Cloudflare Containers rates, which is what the Sandbox SDK runs on and is billed as.

	E2B	Cloudflare Sandbox SDK	Runtime
Isolation	Firecracker microVM, own kernel	A container in its own VM	Firecracker microVM, own kernel
CPU	$0.0504 per allocated vCPU-hour	$0.072 per active vCPU-hour, metered in 10 ms steps	$0.025 per vCPU-hour of measured CPU, with a small floor
Memory	$0.0162 per GiB-hour	$0.009 per provisioned GiB-hour; at least 3 GiB per vCPU	$0.0075 per reserved GiB-hour
Disk	Included, no separate charge	$0.000252 per provisioned GB-hour	Included while running; paused storage $0.08 per GB-month
Plan fee	Hobby $0; Pro $150 a month	Workers Paid, at least $5 a month	None; prepaid credit from $10
Free start	$100 of usage credit, once	No free tier; the plan includes 375 vCPU-minutes a month	50 sandbox hours, no card
When idle	Pause keeps files, memory and processes	Sleeps after 10 idle minutes by default; files are lost	Pause keeps files, memory and processes, 1 to 365 days
Interfaces	API, CLI, MCP server, JavaScript and Python SDKs	A TypeScript SDK called from a Cloudflare Worker	API, CLI, MCP server, JavaScript and Python SDKs

Which is cheaper, E2B or Cloudflare?

For a waiting agent, Cloudflare. It meters CPU only while the code runs, $0.000020 per vCPU-second, and its memory is cheaper per GiB than E2B's. E2B charges for every allocated vCPU from start to stop. Cloudflare's cost comes from its shapes: a custom size needs at least 3 GiB per vCPU, so 2 vCPUs carry 6 GiB, and provisioned disk is billed on top.

That fixed part is about a third of E2B's hourly price, so Cloudflare stays cheaper until the code averages around 1.5 busy CPUs out of 2, some 90 CPU-seconds a minute. At full load E2B wins, $2.76 against $3.35. Runtime meters CPU at $0.025 a vCPU-hour, about a third of Cloudflare's $0.072, with memory set apart from vCPUs, and is below both at any load.

Cost for the same job

The case priced: 1,000 runs on 2 vCPU, 60 seconds each, 20 CPU-seconds of work per run. E2B and Runtime have 4 GiB. Cloudflare's smallest 2 vCPU shape has 6 GiB and is given 12 GB of disk, the size in Cloudflare's example.

TextE2B         CPU    1,000 × 60 s / 3,600 × 2 × $0.0504 = $1.68            Memory 1,000 × 60 s / 3,600 × 4 × $0.0162 = $1.08            Total                                        $2.76Cloudflare  CPU    1,000 × 20 s × $0.000020           = $0.40            Memory 1,000 × 60 s × 6 × $0.0000025      = $0.90            Disk   1,000 × 60 s × 12 × $0.00000007    = $0.05            Total                                        $1.35Runtime     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

That is $276.00 on E2B, $135.04 on Cloudflare and $63.89 on Runtime over 100,000 runs in a month. With both CPUs busy for the whole minute, it is $1.33 on Runtime, $2.76 on E2B and $3.35 on Cloudflare. Cloudflare is priced as if each sandbox were destroyed after its run. Plan fees, Workers requests, Durable Object time, network and free credit are left out.

What happens to an idle sandbox?

A paused E2B sandbox keeps its files, memory and running processes, with no expiry. A Cloudflare sandbox sleeps after 10 idle minutes by default and starts again from its image, with its files gone unless you backed them up to R2 first. A paused Runtime sandbox keeps files, memory and running processes for the retention you set, 1 to 365 days, and wakes on the next request. See how to pause and resume a sandbox.

Which one to pick

• E2B, for a microVM API that any backend can call, paused sandboxes that never expire, or an Apache-2.0 runtime you can host yourself.
• Cloudflare Sandbox, for an app that already runs on Workers and wants its sandboxes on the same account, bill and bindings, near its users.
• Runtime, for CPU billed by use at about a third of Cloudflare's rate, memory sized to the job, a pause that keeps memory and processes, and an API that needs no platform around it.

Moving to Runtime

E2B code changes one import:

TypeScriptimport { Sandbox } from "withruntime/e2b"; // was: from "e2b"

Pythonfrom withruntime.e2b import Sandbox  # was: from e2b import Sandbox

Cloudflare code maps call for call and can then run on any server: getSandbox(env.Sandbox, name) is Sandbox.getOrCreate(name), sandbox.exec(cmd) is exec, and proxyToSandbox is box.previews.create(port). An app that stays on Workers can still call Runtime from the Worker, with SDK 0.4.0 or later and the nodejs_compat flag; the sample is in Runtime vs Cloudflare.

TypeScriptimport { Sandbox } from "withruntime";const box = await Sandbox.create({ funding: "trial" });try {  console.log((await box.exec("python3 -c 'print(6 * 7)'", { check: true })).stdout);} finally {  await box.stop();}

Before the first top-up, npx withruntime switch --from cloudflare or --from e2b matches it with credit, up to $100. A coding agent can handle the port from the one instruction in migration, on a branch and against the free trial. For E2B in depth, see Runtime vs E2B.

Sources

E2B and Cloudflare Containers pricing pages rechecked 25 September 2026; the rest checked 23 September 2026.

• E2B pricing, E2B sandbox persistence
• Cloudflare Containers pricing, Containers limits and instance types, Containers architecture, Sandbox lifecycle, Sandbox backup and restore
• Runtime pricing

Facts on this page were checked on 25 September 2026.