Unbrowse vs Steel: Open Source Browser Infra Compared

Steel and Unbrowse both give AI agents the ability to interact with the web, and both are open source. But they build on opposite foundations. Steel provides cloud browser infrastructure, giving agents access to managed, stealth-capable Chrome instances. Unbrowse provides API intelligence, giving agents the ability to skip the browser entirely and call web APIs directly. Same goal, different bets on where the web is heading.

TL;DR

	Steel	Unbrowse
Approach	Cloud browser API (managed Chrome fleets)	API discovery and direct endpoint execution
Speed	Browser-speed (~3,400ms per page)	Sub-100ms cached, 950ms average
Token cost	Full page DOM (~8,000+ tokens)	Structured JSON (~200 tokens)
Auth handling	Auto sign-in + credential management	Auto cookie extraction from real browsers, 15+ SSO providers
Infrastructure	Cloud-hosted browser fleets	464KB local binary, no cloud dependency
Pricing	Free tier ($10 credit) + paid tiers ($49-$499/mo)	Free (open source), earns x402 micropayments
Best for	Stealth scraping, CAPTCHA-heavy sites, RPA	Data retrieval, API-heavy sites, cost-sensitive agent pipelines

What is Steel?

Steel is an open-source browser API that lets you control fleets of browsers in the cloud, built specifically for AI agents. It provides managed Chrome instances with built-in stealth capabilities, CAPTCHA solving, proxy management, and session persistence, all accessible through a simple API.

The platform is designed for drop-in compatibility with existing browser automation tools. You can swap puppeteer.launch() for puppeteer.connect() and immediately run your Puppeteer, Playwright, or Selenium scripts on Steel's cloud infrastructure. SDKs are available for Python and Node.js.

Steel differentiates from other cloud browser providers through its focus on AI agent use cases. Sessions start in under one second. Cookie and local storage persistence enables context reuse across sessions. The Session Viewer provides live debugging and recording. Built-in CAPTCHA solving and browser fingerprinting help agents navigate sites with anti-bot measures.

The platform has processed over 800 billion tokens of scraped content and served more than 800,000 browser hours, demonstrating meaningful enterprise adoption. Pricing ranges from a free tier with $10 in monthly credits to enterprise plans, with the popular developer tier at $99/month for about 1,238 browser hours.

Steel solves real problems. Running browser infrastructure at scale is operationally complex, and Steel handles the hard parts: browser lifecycle management, proxy rotation, stealth configuration, and CAPTCHA solving. For teams that need reliable browser automation in the cloud, it removes significant operational burden.

What is Unbrowse?

Unbrowse takes the opposite approach. Instead of providing better browser infrastructure, it eliminates the need for browser infrastructure.

Unbrowse is an API-native agent browser powered by Kuri, a 464KB Zig-native CDP broker with a 3ms cold start. When an agent needs data from a website, Unbrowse checks whether the underlying API endpoints have already been discovered. If they have, it calls them directly, returning structured JSON without launching a browser. No page rendering, no DOM parsing, no JavaScript execution.

The discovery process is passive and automatic. During an initial browsing session, Unbrowse captures all network traffic (HAR recording plus fetch/XHR interception), identifies API endpoints, and reverse-engineers their schemas: URL templates, authentication headers, request bodies, and response structures. These routes are cached locally and published to a shared marketplace where any agent can use them.

This creates a powerful network effect. The more agents use Unbrowse, the more routes are discovered and cached, and the less frequently any agent needs a browser. The peer-reviewed benchmark across 94 live domains (arxiv.org/abs/2604.00694) shows a 3.6x mean speedup and 5.4x median speedup, with cached routes completing in under 100ms.

Key Differences

Architecture

Steel is infrastructure for browsers. It manages cloud Chrome instances, handles their lifecycle, provides stealth and anti-detection features, and exposes a clean API for controlling them. Under the hood, every request still goes through the full browser pipeline: page load, JavaScript execution, DOM construction, rendering. Steel makes this process more reliable and easier to manage, but the fundamental architecture is browser-centric.

Unbrowse is intelligence about APIs. It understands the data layer beneath web pages and routes requests directly to API endpoints. The browser is a discovery tool used during initial indexing, not a permanent dependency. For any site that has been previously indexed, the browser is completely out of the picture.

The analogy: Steel builds better highways for cars. Unbrowse builds a teleportation network that makes the highways unnecessary.

Performance

Steel's browser sessions start in under one second, which is fast for browser infrastructure. But once the session starts, you are still operating at browser speed: approximately 3,400ms per page interaction including page load, JavaScript execution, and content extraction. Steel optimizes the infrastructure around the browser, but cannot overcome the browser's inherent latency.

Unbrowse cached routes return in under 100ms. That is 34x faster than a typical browser-based interaction. Even for uncached routes where Unbrowse falls back to a browser session, the average is 950ms, because the session only needs to capture API calls rather than fully render the page.

For multi-step agent workflows, this compounds dramatically. A ten-step data retrieval task takes 34 seconds through browser automation. Through Unbrowse cached routes, it takes one second.

Token Efficiency

When Steel delivers a rendered page to your agent, the agent receives the full DOM. A typical web page generates 8,000 to 50,000 tokens of HTML content, most of which is irrelevant to the data the agent actually needs. Navigation, footers, ads, tracking scripts, and styling markup all consume context window space.

Unbrowse returns structured API responses: typically 200 to 500 tokens of clean JSON containing exactly the data the agent requested. That is a 40x reduction in token consumption per action.

At Steel's scale of 800 billion tokens scraped, imagine the savings if even a fraction of those requests could have been served by direct API calls at 1/40th the token count. The efficiency difference is staggering.

Cost

Steel's pricing is per-session and per-hour. The developer tier at $99/month includes roughly 1,238 browser hours. As your agent fleet scales and runs more browser sessions, costs increase linearly. Heavy users can reach the Scale tier at $499/month or need enterprise pricing.

Unbrowse is entirely free and open source. The Kuri runtime is a single 464KB binary that runs locally. Cached route execution has negligible cost, as it is just an HTTP call. The x402 micropayment marketplace actually pays agents for contributing route discoveries, turning heavy usage into a revenue source rather than a cost center.

The economic model is inverted: Steel charges more as usage increases. Unbrowse becomes cheaper (even profitable) as more agents contribute to the route network.

Stealth and Anti-Detection

Steel invests heavily in stealth: browser fingerprint management, proxy rotation, CAPTCHA solving, and anti-detection measures. This is necessary because browser automation is inherently detectable, as sites can identify non-human browsing patterns.

Unbrowse sidesteps this problem for cached routes. Direct API calls look identical to the site's own frontend JavaScript making the same calls. There is no browser to fingerprint, no automation to detect. The requests carry real authentication cookies and follow the same patterns the site's own code uses. For the server, an Unbrowse API call is indistinguishable from a normal user's browser making a background fetch.

When to Use Steel

Steel is the right choice when:

• CAPTCHA-heavy sites where automated solving is essential
• Complex browser interactions: multi-step forms, drag-and-drop, visual workflows
• Stealth-critical scraping: sites with aggressive anti-bot measures where browser fingerprinting matters
• Session persistence: long-running tasks that need maintained browser state
• Screenshot and recording needs: visual documentation, QA, compliance
• Drop-in cloud migration: moving existing Puppeteer/Playwright scripts to the cloud without rewriting

When to Use Unbrowse

Unbrowse is the clear choice when:

• Speed is the priority: sub-100ms vs seconds per interaction
• Cost must be minimized: free open source vs monthly subscription
• Token efficiency is critical: 200 tokens vs 8,000+ per action
• Structured data is the goal: JSON responses vs DOM parsing
• No cloud dependency: runs locally with a 464KB binary
• Multi-agent intelligence: shared marketplace means routes discovered by one agent benefit all
• MCP integration: Unbrowse works as an MCP server for any agent framework

Getting Started with Unbrowse

npm install -g unbrowse
unbrowse setup

Resolve structured data from any URL:

unbrowse resolve "get search results" --url https://example.com/search?q=test

No cloud account, no browser fleet management, no monthly subscription. Install and resolve.

The Bottom Line

Steel and Unbrowse represent two philosophies of how AI agents should interact with the web. Steel says: agents need browsers, so let us build the best browser infrastructure possible. Unbrowse says: agents need data, and browsers are just one way to get it, usually the slowest and most expensive way.

Both philosophies have valid use cases today. Some sites require full browser interaction: CAPTCHAs, complex UIs, visual verification. Steel handles those well. But for the growing majority of web interactions where agents need structured data from API-backed sites, Unbrowse is 3.6x faster, 40x more token-efficient, and free.

The trajectory favors API discovery. As more sites adopt API-first architectures and the Unbrowse route marketplace grows, the set of tasks that genuinely require a browser will continue to shrink. Building on browser infrastructure today means building on a layer that is becoming increasingly optional. Building on API intelligence means building on the layer that everything else already depends on.