Sandbox profile · Hosted platform

Runtime

Answer in brief

Firecracker microVM sandboxes billed on active CPU at $0.025 per vCPU-hour, with pause that keeps memory, forks, SDKs in five languages and no plan fee. Aggressively priced and feature-dense, but single-region and unaudited; well suited to cost-driven batch agent work rather than regulated deployments.

By the Agent Sandboxes editors · Updated November 9, 2026

Overview

Runtime is a hosted sandbox service from Runtime LLC of Denver, Colorado. Each sandbox is a Firecracker microVM with its own kernel on servers Runtime operates in a Virginia data centre. The client side is unusually broad: SDKs for JavaScript, Python, Go, Ruby and Java, a CLI, an MCP server and an OpenAPI-described HTTP API, all Apache-2.0 on GitHub, plus a code interpreter for Python, JavaScript, TypeScript, R, Java, Bash and Go, desktop automation, Docker inside sandboxes, SSH, scheduled jobs, signed webhooks and OpenTelemetry export. Migration guides cover code written for E2B, Daytona, Vercel Sandbox, Blaxel, Morph, Modal and Cloudflare.

The pricing model is the pitch: CPU is billed only while active at $0.025 per vCPU-hour, memory at $0.0075 per reserved GiB-hour, with no plan fee and a renewing free allowance of 100 GiB-hours; the vendor's own price index claims 42% to 88% lower cost than fourteen providers for a 1,000-run example job. Sandboxes pause after five minutes idle by default, keeping memory and processes, and can be forked into up to ten running copies. Governance features (SSO, SCIM, roles, 400-day audit log, DPA) are free, but Runtime holds no certification of its own and publishes only its subprocessors' attestations. The speed page currently shows no figures, having withdrawn them on 27 October 2026.

Notable

Pricing page (checked 25 October 2026 by the vendor): example job of 1,000 one-minute runs costs $0.64 on Runtime against $1.11 to $5.33 elsewhere, a vendor comparison.
Limits with credit: 100 sandboxes at once (200 with auto top-up), up to 16 vCPU, 64 GiB and 400 GiB disk each; 1,000 kept sandboxes.
Client repository is Apache-2.0 with 1 GitHub star at verification; payment accepted by card or USDC on Base, Solana or Tempo.

Runtime specifications

Attribute	Details
Isolation	Firecracker microVM with its own Linux kernel, disk and memory per sandbox, on dedicated servers Runtime operates
Deployment	Hosted platform
Open source	No
SDKs and interfaces	JavaScript/TypeScript, Python, Go, Ruby, Java, CLI, REST API, MCP server
Cold start (vendor claim)	Runtime measures create and exec from outside every one to five minutes and publishes p50/p95/p99 on its speed page; the September 2026 figures were taken down on 27 October 2026 pending re-measurement, so no current figure is published
Max session length	No maximum documented; a sandbox pauses itself after 300 seconds of inactivity by default (`idlePauseSeconds` 60–86,400, or 0 for never)
Persistence	Pause keeps memory and processes; paused sandboxes are kept while the account has credit or for 1–365 days as set (30 days after credit runs out with a card or prior top-up, 7 days otherwise); snapshots of running or paused sandboxes; forks of 1–10 running copies with memory and processes; volumes backed up daily; S3, R2 and GCS bucket mounts
GPU	Not documented
Networking	Per-sandbox allow and deny lists, or internet off; sandboxes reach only the public internet, private addresses refused; HTTPS previews on runtimehost.com (private by default with rotatable tokens), custom domains, public TCP ports, WireGuard private networks and a dedicated outbound IPv4 ($5 per 30 days); secrets substituted by the host on outbound requests
Pricing	$0.025 per active vCPU-hour and $0.0075 per reserved GiB-hour, billed per second; a waiting sandbox bills memory plus a 0.05 vCPU floor; paused sandboxes, snapshots and images $0.08 per GB per 30-day month; volumes about $0.11 per GiB per 30 days; outbound traffic free to 100 GiB a month then $0.02 per GB; no plan, seat or minimum fee
Free tier	100 free hours of a 1 GB machine (100 GiB-hours of memory, 25 vCPU-hours of active CPU) in the first 30 days with no card, renewing monthly once the account has paid; without credit up to 4 sandboxes at once of 2 vCPU and 4 GiB
Compliance	No certification of Runtime itself is named; the trust page lists subprocessor attestations (Virginia data centre SOC 1/2/3 Type 2 and ISO 27001; Neon and Vercel SOC 2 Type 2); DPA included in every account; SAML/OIDC SSO and SCIM free; 99% monthly API uptime promise on paid accounts
Regions	All processing in one region in Virginia, United States (trust page); limits are counted per region

Facts from Runtime’s public documentation, verified November 9, 2026. Performance numbers are vendor claims.

Strengths and trade-offs

Strengths

You want the lowest published per-vCPU rate with billing only for active CPU.
You need SDKs in Go, Ruby or Java as well as Python and TypeScript.
You want SSO, SCIM, audit logging and a DPA without an enterprise contract.
You run many short agent jobs and want a renewing free monthly allowance.

Trade-offs

Single region (Virginia, US) with no option to run elsewhere.
No startup latency figures are currently published, and no own compliance certification.
Young service with a minimal public footprint (1 star on the client repository).
Waiting sandboxes still bill memory plus a CPU floor, so idle time is not free unless paused.

Good fit for: Cost-sensitive agent workloads with many short runs, where active-CPU billing and a free monthly allowance matter.

How Runtime compares

Sandbox	Isolation	Open source	Self-host / BYOC	Cold start (vendor)	Max session	Snapshots / pause	GPU	SDKs
Runtime	Firecracker microVM	No	No / No	Not documented	No limit documented	Yes / Yes	Not documented	JavaScript/TypeScript, Python, Go, Ruby, Java, CLI, REST API, MCP server
E2B	Firecracker microVM	Yes	Yes / Yes	Not documented	1 h / 24 h (Pro)	Yes / Yes	No	Python, JavaScript/TypeScript
Daytona	Containers or VMs	No	Not documented / Yes	<90 ms	Unlimited	Yes / Yes	Yes	Python, TypeScript, Ruby, Go, Java
Superserve	Firecracker microVM	No	No / Yes	Not documented	Unlimited	Yes / Yes	Not documented	Python, JavaScript/TypeScript, CLI, REST API, MCP server
InstaVM	Firecracker microVM	No	No / No	<200 ms (claim)	Configurable	Yes / Yes	Not documented	Python, JavaScript/TypeScript, CLI, REST API
Leap0	Firecracker microVM	No	No / Yes	~100 ms (claim)	8 h max	Yes / Yes	Not documented	Python, JavaScript/TypeScript, Go, MCP server
Tenki Sandbox	Single-tenant VM	No	No / No	<1 s (claim)	Configurable; sticky = unlimited	Yes / Yes	Not documented	JavaScript/TypeScript, Python, Go, CLI

See all Runtime alternatives →

Frequently asked questions

What is Runtime?

How does Runtime isolate code?

Runtime documents its isolation as: Firecracker microVM with its own Linux kernel, disk and memory per sandbox, on dedicated servers Runtime operates.

Is Runtime open source?

No, Runtime is not open source.

How much does Runtime cost?

$0.025 per active vCPU-hour and $0.0075 per reserved GiB-hour, billed per second; a waiting sandbox bills memory plus a 0.05 vCPU floor; paused sandboxes, snapshots and images $0.08 per GB per 30-day month; volumes about $0.11 per GiB per 30 days; outbound traffic free to 100 GiB a month then $0.02 per GB; no plan, seat or minimum fee Check the official pricing page for current rates.

What are the alternatives to Runtime?

Common alternatives include E2B, Daytona, Superserve, InstaVM, Leap0, Tenki Sandbox. See Runtime alternatives for a full comparison.

Sources

Cite this page

Agent Sandboxes. (2026). Runtime. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/sandboxes/withruntime/

Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.