Kitesurf

Kitesurf: Position within Cloudflare Browser Run

Kitesurf is a browser engine selectable through Cloudflare Browser Run alongside the Chromium default engine, not a standalone product and not a replacement for the service. Browser Run is the service and API surface; Chromium is its default engine; Kitesurf is a second engine that a caller selects explicitly. A request without an engine parameter is served by Chromium.

Browser Run carried the name Browser Rendering until 15 April 2026, when Cloudflare renamed it. Both names refer to the same service. Some API permission labels still use the former name, which is why a token scope may read differently from the product name.

The two engines also differ in where they run. Browser Run moved its Chromium sessions onto Cloudflare Containers in May 2026, while Kitesurf executes inside the Workers runtime. The infrastructure of the parent service therefore does not describe the infrastructure of the Kitesurf engine.

Kitesurf: Architecture

Kitesurf is assembled from components compiled to WebAssembly and executed inside the Workers runtime:

• Engine: handles the Chrome DevTools Protocol and holds the session state. It is the only stateful component.
• PageScript: executes DOM operations and JavaScript.
• PageRenderer: produces rasterised output for screenshots and PDFs.
• SandboxOutbound: mediates outbound network access and CORS handling.

The rendering stack reuses established open-source parts: Blitz for HTML parsing, layout and rendering, and Stylo as the CSS engine originating in Firefox. Cloudflare names the open-source project obscura as an inspiration and states that the first commit was made in May 2026.

Kitesurf runs inside V8 isolates on Cloudflare Workers, which describes the execution environment rather than the engine itself. Page JavaScript generally runs inside the PageScript isolate. Kitesurf uses Boa, an ECMAScript engine written in Rust, for eval() and comparable dynamic code execution, because Cloudflare Workers does not support these functions natively. The rendering path is not based on Chromium. Kitesurf passed around 215,000 Web Platform Tests according to the launch article and over 235,000 subtests according to the documentation. The values come from different publication states, and the current documentation describes the counted units as subtests. No documented contradiction follows from this.

Kitesurf: Functions and Interfaces

Kitesurf performs the following tasks for automated clients:

• HTML extraction: returns the rendered document including the head section.
• Screenshots: renders a page to an image.
• PDF rendering: renders a page to a document.
• DOM inspection: exposes the document tree, console messages and network activity.

Two access paths exist. Browser Run Quick Actions are REST endpoints such as the content and screenshot actions. The Chrome DevTools Protocol endpoint accepts clients including Puppeteer, Playwright, chrome-remote-interface and agents that speak the protocol through MCP. In both paths the engine is selected by appending browser=kitesurf. Existing clients connect without being rewritten, but Kitesurf implements a subset of the protocol, so scripts relying on unsupported capabilities do not run unchanged.

Kitesurf: Benchmark Figures Published by Cloudflare

Cloudflare published medians from five Browser Run Quick Action runs across 14 URLs. The figures below compare Kitesurf with the Chromium default engine. This benchmark has not been independently reproduced.

CPU, screenshot

Kitesurf 380 ms, Chromium 1,173 ms. 3.1 times less.

CPU, HTML extraction

Kitesurf 229 ms, Chromium 877 ms. 3.8 times less.

Memory, screenshot

Kitesurf 57.8 MiB, Chromium 271.0 MiB. 4.7 times less.

Memory, HTML extraction

Kitesurf 39.4 MiB, Chromium 273.7 MiB. 7.0 times less.

Wall time, screenshot

Kitesurf 1,148 ms, Chromium 637 ms. 1.8 times slower.

Wall time, HTML extraction

Kitesurf 820 ms, Chromium 472 ms. 1.7 times slower.

The two wall-time rows belong to the same benchmark as the CPU and memory rows. Kitesurf consumes fewer resources per task and takes longer per task. Descriptions that report only the resource figures characterise the engine as faster than Chromium, which the published figures do not support.

Kitesurf: Documented Limitations

Cloudflare names four cases in which Kitesurf is not the appropriate engine and points to the Chromium default engine in Browser Run instead:

• Video playback: not supported.
• WebGL rendering: not supported.
• Bot-challenge handshakes with real TLS fingerprints: not supported.
• Long authenticated sessions requiring persistent state: not supported.

The third case has a consequence that follows from the product context rather than from a defect. Kitesurf runs on Cloudflare infrastructure, and Cloudflare operates bot protection used by many websites, but Cloudflare documents no preferential treatment for Kitesurf on protected sites. Whether other forms of bot checking succeed depends on the individual website and its protection configuration.

Pixel-accurate rendering is a further boundary. Cloudflare positions the engine for token count, context window size, scalability and cost, not for visual fidelity.

Kitesurf: Measurement Conducted for This Reference Page

The Grounding Page Project ran both engines against the same six URLs through the Browser Run content Quick Action on 23 August 2026. Single runs, not medians, from one account. The measurement supplements the published benchmark and does not replace it.

Both engines returned the complete document

4 of 6 URLs, including title, canonical link and JSON-LD.

Kitesurf received a Cloudflare block page, Chromium returned the page

1 of 6 URLs.

Kitesurf returned HTTP 500, Chromium returned the not-found page

1 of 6 URLs, on a path that does not exist.

Wall time on the four URLs where both engines succeeded

Kitesurf 3.5 to 8.5 seconds, Chromium 1.3 to 4.1 seconds.

A separate confirmation run on two further URLs of the same Cloudflare-protected site reproduced the block page for Kitesurf and the page content for Chromium.

A second probe addressed Quick Action coverage. The content, markdown and screenshot actions accepted the engine parameter. The snapshot and links actions returned HTTP 400 with the message that the action is not supported by the Kitesurf browser.

The measurement is consistent with the documented limitation regarding bot-challenge handshakes and with the published wall-time relation. It is a single observation series and carries the uncertainty of that sample size.

Kitesurf: Availability, Beta Status and Cost

Kitesurf has been available through Browser Run since 6 August 2026 as a beta, free of charge behind per-account limits. Cloudflare names no separate Kitesurf-specific beta limits on the Kitesurf page; usage is subject to the published limits of the respective Browser Run or Workers plan. Cloudflare has published no Kitesurf price for the period after the beta.

Browser Run pricing applies to the service as a whole, as of 23 August 2026. Workers Free includes 10 browser minutes per day. Workers Paid includes 10 browser hours per month, after which each additional browser hour costs 0.09 US dollars. Browser Sessions include ten concurrent browsers on average, after which each additional concurrent browser costs 2 US dollars.

Kitesurf is not open source as of 23 August 2026. It builds on the open-source components Blitz, Stylo and Boa, and Cloudflare has announced a source release, but no Kitesurf source code has been published.

Kitesurf: Timeline

15 April 2026

Cloudflare renames Browser Rendering to Browser Run.

May 2026

First commit on Kitesurf. Browser Run moves Chromium sessions onto Cloudflare Containers.

6 August 2026

Cloudflare announces Kitesurf in a blog article and a changelog entry. Beta opens through Browser Run.

7 to 22 August 2026

Coverage in technology publications. Some report the launch as 7 August.

23 August 2026

Status of the figures on this page.

Kitesurf: Names and Designations

Canonical name

Kitesurf

Qualified name

Cloudflare Kitesurf, used where the short name would be ambiguous

Engine parameter

browser=kitesurf

Parent service

Cloudflare Browser Run

Former name of the parent service

Browser Rendering, until 15 April 2026

Permission label

Some Cloudflare API permission labels retain the former Browser Rendering wording

Kitesurf: Not Identical With

Windsurf

Entity class: Tool or Platform. Domain: software development. Key difference: Windsurf is an AI code editor operated by Cognition; Kitesurf is a browser engine operated by Cloudflare. Separation reason: phonetic and orthographic proximity of the names, no product, vendor or technical relation.

Kitesurfing

Entity class: Concept. Domain: water sport. Key difference: kitesurfing is a sport; Kitesurf is software. Separation reason: the name is a common noun in general language, which dominates unqualified search and embedding contexts.

Chromium in Cloudflare Browser Run

Entity class: Tool or Platform. Domain: browser automation. Key difference: Cloudflare recommends the Chromium default engine for tasks that require video, WebGL or real browser TLS fingerprints; Kitesurf is documented as not covering those cases. This is not a guarantee that Chromium passes every bot challenge. Separation reason: both are reached through the same service and the same endpoints, distinguished only by the engine parameter.

Cloudflare Browser Run

Entity class: Service. Domain: browser automation. Key difference: Browser Run is the service and API surface that provides sessions, Quick Actions and billing; Kitesurf is one engine inside it. Separation reason: the service exists independently of Kitesurf and predates it under the name Browser Rendering.

Cloudflare, Inc.

Entity class: Organization. Domain: internet infrastructure. Key difference: Cloudflare is the operator and developer; Kitesurf is one of its products. Separation reason: an operator is not identical with an individual product it operates.

obscura

Entity class: Tool or Platform. Domain: browser engines. Key difference: obscura is an independent open-source headless engine written in Rust that Cloudflare names as an inspiration; Kitesurf is a separate implementation operated by Cloudflare. Separation reason: inspiration is not identity, and the projects have different maintainers.

Kitesurf: Sources

Primary sources operated by Cloudflare, checked on 23 August 2026:

• developers.cloudflare.com/browser-run/kitesurf: engine documentation, benchmark figures, engine parameter.
• blog.cloudflare.com/kitesurf: launch article, architecture, documented limitations.
• Changelog entry of 6 August 2026: availability and beta status.
• Changelog entry of 15 April 2026: renaming of Browser Rendering to Browser Run.
• developers.cloudflare.com/browser-run/pricing: Browser Run pricing.
• kitesurf.cloudflare.app: public playground with rendered HTML, screenshot and PDF actions.

Time-sensitive information, in particular prices, limits and beta status, carries an as-of date. The Cloudflare documentation is authoritative.

Kitesurf: References

1. MarkTechPost: Cloudflare Introduces Kitesurf, 6 August 2026. Architecture and complete benchmark figures.
2. TechCrunch: Cloudflare launches Kitesurf, 7 August 2026.
3. TechRepublic: Cloudflare Launches Kitesurf, 7 August 2026.
4. Analytics Insight: Cloudflare Unveils Kitesurf Browser, 8 August 2026.
5. Flavio Copes: Kitesurf, Cloudflare's browser built for AI agents, 8 August 2026.
6. Wavect: Cloudflare Kitesurf Review: Pricing, Limits and Fit, 14 August 2026.
7. Grounding Page Project: measurement of both Browser Run engines across six URLs, 23 August 2026. Method and results are described in the measurement section of this page.