Sandbox profile · Hosted platform

Steel

Answer in brief

Open-source browser API for agents (Apache-2.0, self-hostable with Docker) with a managed Steel Cloud adding stealth, captcha solving, profiles and a hosted MCP server. The open-source choice among hosted browser APIs: self-host for free, move to Steel Cloud for stealth, captchas and concurrency.

By the Agent Sandboxes editors · Updated November 9, 2026

Overview

Steel is an open-source browser API for AI agents. Steel Browser, the Apache-2.0 server on GitHub, runs Chromium under Puppeteer and CDP and exposes a sessions API that Playwright, Puppeteer, Selenium or any CDP client can connect to; you can run it with a single docker run or deploy to Railway. Steel Cloud is the managed version, with SDKs for TypeScript, Python, Go and Rust, a CLI, and a hosted MCP server at mcp.steel.dev. Each session launches its own isolated Chromium; the docs do not describe the boundary beneath it.

Sessions default to 5 minutes and are capped per plan (15 minutes, 1 hour or 24 hours). Profiles persist a browser's user data directory for later sessions, and dedicated IPs give a stable network identity. The cloud adds captcha solving, managed proxies, a Credentials API, a Files API and advanced stealth that the local build lacks; the docs say the defining difference is concurrency (1 locally versus 10 to 1,000+ on the cloud). Pricing is per browser hour plus proxy and captcha usage.

Notable

Steel Browser has 7.9k GitHub stars; the homepage claims 35M+ sessions and 1.5M+ browser hours served
Launch Week v3 (post dated 29 June 2026) added the Stealth Browser Chromium fork, Dedicated IPs, and Rust and Go SDKs
Hosted MCP server at https://mcp.steel.dev/mcp with OAuth or API-key sign-in

Steel specifications

Attribute	Details
Isolation	Each session launches its own isolated Chromium in the cloud; the container or VM boundary is not named. Self-hosted Steel Browser runs as a Docker container
Deployment	Hosted platform · Self-hostable
Open source	Yes (Apache-2.0)
SDKs and interfaces	Python, JavaScript/TypeScript, Go, Rust, CLI, REST API, MCP server
Cold start (vendor claim)	Not documented
Max session length	Sessions last 5 minutes by default (configurable timeout, optional inactivityTimeout); maximum 15 minutes on Launch, 1 hour on Scale, up to 24 hours on Enterprise
Persistence	Each session keeps its own cookies and storage; Profiles snapshot the browser user data directory (cookies, auth, extensions, settings) for reuse via profileId, up to 300 MB, deleted after 30 days unused
GPU	No — not offered
Networking	Residential and datacenter proxies with country-to-city targeting or bring your own; dedicated IPs ($5/IP/month on Scale); captcha solving; stealth fingerprinting and an Enterprise-only Stealth Browser Chromium fork
Pricing	Launch $0 + usage: $0.10 per browser hour, 10 concurrent sessions, proxy $10/GB, captcha $3 per 1k. Scale $250/month + usage: $100 credits/month, $0.08 per browser hour, 100 concurrent, proxy $6/GB, captcha $1 per 1k. Enterprise: custom, 1,000+ concurrent. Billed per minute, rounded up
Free tier	$30 one-time credits on the Launch plan (no monthly fee, no card required); Steel Browser is free to self-host
Compliance	HIPAA BAA listed for Enterprise; a trust centre is published (certifications not readable from the pages fetched)
Regions	Not documented

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

Strengths and trade-offs

Strengths

You want an Apache-2.0 browser server you can self-host with Docker
You need a managed cloud with the same API when concurrency grows
You want SDKs beyond Node and Python (Go and Rust)
You are connecting an MCP client and want a hosted server with profiles and saved logins

Trade-offs

Launch plan sessions are capped at 15 minutes; 24-hour sessions need Enterprise
Isolation boundary and regions are not documented
Captcha solving, credentials, files and the MCP server are cloud-only
Compliance certifications were not readable from the trust centre

Good fit for: Teams that want an open-source browser API they can run themselves or scale on a managed cloud.

Use cases Steel fits

Computer use: Open-source (Apache-2.0) browser API with Playwright, Puppeteer and Selenium support, self-hostable or on a managed cloud.
Open source & self-hosted: Apache-2.0 browser API for computer-use agents, self-hostable or managed.

How Steel compares

Sandbox	Isolation	Open source	Self-host / BYOC	Cold start (vendor)	Max session	Snapshots / pause	GPU	SDKs
Steel	Isolated Chromium session	Yes	Yes / No	Not documented	15 min / 1 h / 24 h	No / No	No	Python, JavaScript/TypeScript, Go, Rust, CLI, REST API, MCP server
Browserbase	Isolated Chromium session	No	No / No	<2 s (claim)	6 h (15 min Free)	No / No	No	Python, JavaScript/TypeScript, REST API, MCP server
Browserless	Not documented	Yes	Yes / No	Not documented	2 min to 60 min by plan	No / No	Yes	JavaScript/TypeScript, Python, CLI, REST API, MCP server
Hyperbrowser	Isolated browser instance	No	No / No	<500 ms (claim)	Up to 12 h	No / No	No	Python, JavaScript/TypeScript, CLI, REST API, MCP server
Kernel	Unikernel VM per browser	Yes	Yes / No	~30 ms p50 (claim)	Up to 72 h	Yes / Yes	Yes	JavaScript/TypeScript, Python, Go, CLI, REST API, MCP server
Notte	Isolated browser instance	Yes	No / No	Not documented	15 min to 5 h by plan	No / No	No	Python, JavaScript/TypeScript, CLI, REST API, MCP server
Lightpanda	Not documented	Yes	Yes / No	Not documented	15 min per connection	No / No	No	CLI, REST API, MCP server

See all Steel alternatives →

Frequently asked questions

What is Steel?

How does Steel isolate code?

Steel documents its isolation as: Each session launches its own isolated Chromium in the cloud; the container or VM boundary is not named. Self-hosted Steel Browser runs as a Docker container.

Is Steel open source?

Yes (Apache-2.0). It can be self-hosted.

How much does Steel cost?

Launch $0 + usage: $0.10 per browser hour, 10 concurrent sessions, proxy $10/GB, captcha $3 per 1k. Scale $250/month + usage: $100 credits/month, $0.08 per browser hour, 100 concurrent, proxy $6/GB, captcha $1 per 1k. Enterprise: custom, 1,000+ concurrent. Billed per minute, rounded up Check the official pricing page for current rates.

What are the alternatives to Steel?

Common alternatives include Browserbase, Browserless, Hyperbrowser, Kernel, Notte, Lightpanda. See Steel alternatives for a full comparison.

Sources

Cite this page

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

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