Cloudflare Sandbox vs Blaxel: pricing, idle costs and limits

Cloudflare bills active CPU plus provisioned memory; Blaxel bills memory only, with CPU included, and goes to standby within seconds.

For an agent that waits on a model, Runtime costs 53% less than Cloudflare and 77% less than Blaxel. The test job, 1,000 one-minute runs at 2 vCPU, is $1.35 on Cloudflare, $2.76 on Blaxel and $0.64 on Runtime. Cloudflare ties memory to vCPUs and Blaxel ties CPU to memory; Runtime prices the two apart, $0.025 per measured vCPU-hour and $0.0075 per GiB-hour, so neither drags the other up. Rates checked 23 September 2026.

At a glance

Cloudflare prices its Sandbox SDK as Cloudflare Containers, so those are the rates shown.

	Cloudflare Sandbox SDK	Blaxel	Runtime
Isolation	A container in its own VM	Lightweight virtual machines	Firecracker microVM, own kernel
CPU	$0.072 per active vCPU-hour, metered in 10 ms steps	Included with memory; 8 GB gets 4 cores	$0.025 per vCPU-hour of measured CPU, with a small floor
Memory	$0.009 per provisioned GiB-hour; at least 3 GiB per vCPU	$0.0000115 per GB-second of active time	$0.0075 per reserved GiB-hour
Idle	Sleeps after 10 idle minutes by default; files are lost	Standby about 15 s after connections close	Pause keeps files, memory and processes, 1 to 365 days
Kept when idle	Nothing, unless backed up to R2	Files and running processes, in a snapshot	Files, memory and running processes
Idle storage	None kept	$0.20 per GB-month of snapshot	$0.08 per GB-month
Plan fee	Workers Paid, at least $5 a month	None; tiers grow with credit added	None; prepaid credit from $10
Free start	No free tier; the plan includes 375 vCPU-minutes a month	Up to $200 of credit	50 sandbox hours, no card
Interfaces	A TypeScript SDK called from a Cloudflare Worker	TypeScript and Python SDKs	API, CLI, MCP server, JavaScript and Python SDKs

What does each one charge while the agent is idle?

This is where the two differ most. A Blaxel sandbox goes to standby about 15 seconds after its last connection closes. In standby Blaxel charges nothing for memory, only for the snapshot's storage, and reconnecting resumes the sandbox in under 25 ms with its files and running processes. Blaxel's docs note that external connections, such as database connections or HTTP pools, are not kept.

A Cloudflare sandbox that is not destroyed stays up, billing its provisioned memory and disk, until it has been idle for 10 minutes by default. Those ten minutes cost $9.50 per 1,000 sandboxes at the 2 vCPU, 6 GiB, 12 GB size below, several times the job itself. When it does sleep, its files and processes are gone. Set sleepAfter lower, or destroy each sandbox when its run ends.

On Runtime, stop a sandbox when its run ends, or set idlePauseSeconds so it pauses by itself and wakes on the next request with memory and processes intact:

TypeScriptimport { Sandbox } from "withruntime";const sbx = await Sandbox.create({ idlePauseSeconds: 600 }); // ten idle minutesawait sbx.update({ idlePauseSeconds: 1800 }); // change it later; 0 turns it off

Pythonfrom withruntime import Sandboxsbx = Sandbox.create(idle_pause_seconds=600)sbx.update(idle_pause_seconds=1800)  # 0 turns it offsbx.stop()

Cost for the same job

The sums below price 1,000 runs of 60 seconds on 2 vCPU, each with 20 CPU-seconds of real work. Blaxel gets 4 GB and Runtime 4 GiB. Cloudflare asks for at least 3 GiB per vCPU, so it is sized at 6 GiB, with the 12 GB of disk from Cloudflare's own example.

TextCloudflare  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                                        $1.35Blaxel      Memory 1,000 × 60 s × 4 × $0.0000115      = $2.76Runtime     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

Across 100,000 runs in a month the bills are $135.04 on Cloudflare, $276.00 on Blaxel and $63.89 on Runtime. When both CPUs are busy for the whole minute, the job is $1.33 on Runtime, $3.35 on Cloudflare and $2.76 on Blaxel. Between the two rivals, Cloudflare stays cheaper until a run uses about 90 of its 120 CPU-seconds: its CPU is metered, while Blaxel's is bundled into a flat memory rate. The Cloudflare total assumes each sandbox is destroyed at the end of its run. The Blaxel total assumes standby starts the instant a run ends; in practice it starts about 15 seconds later, which adds $0.69 per 1,000 runs. Not counted: plan fees, Workers requests, Durable Object time, storage, network and free credit.

Which one to pick

If what matters most is	Choose
Sandboxes inside a Workers app, near users	Cloudflare Sandbox
Free idle time and a resume in about 25 ms	Blaxel
Over 100,000 sandboxes at once, on its top tier	Blaxel
The lowest bill of the three at any load	Runtime

Runtime also keeps a paused sandbox's memory for $0.08 per GB-month, and its API works from any backend rather than from inside a Worker.

Porting from each

Cloudflare code maps call for call: getSandbox(env.Sandbox, name) to Sandbox.getOrCreate(name), sandbox.exec(cmd) to exec, proxyToSandbox to box.previews.create(port). Blaxel's standby has a direct counterpart in Runtime's automatic wake, which is on by default, so a request to a paused sandbox brings it back. Blaxel's create, run, file and delete calls become Sandbox.create(), exec, files.write and files.read, and stop().

The migration guide gives one instruction for a coding agent that ports the project on a branch and checks it on the free trial. Coming from Cloudflare, npx withruntime switch --from cloudflare before the first top-up matches it with credit, up to $100. Longer reads: Runtime vs Cloudflare, Runtime vs Blaxel and how to pause and resume a sandbox.

Sources

Rates checked 23 September 2026; Blaxel's sandbox overview and Cloudflare's sandbox lifecycle page read 25 September 2026.

• Cloudflare Containers pricing, Containers limits and instance types, Sandbox lifecycle
• Blaxel pricing, Blaxel sandboxes
• Runtime pricing

Facts on this page were checked on 25 September 2026.