Compare / browsers

WebKit vs Chromium

Playwright's WebKit 26.4 claims a Mac in its user agent but reports Linux, sets navigator.webdriver and speaks HTTP/1.1 through a proxy. Where it beats Chromium (CSS, testing), and why it is not an iPhone's browser.

WebKit Chromium

WebKit on the fleet is the WebKit build that ships with Playwright — the engine behind Apple's browser, compiled for Linux — at version 26.4. Chromium is Playwright's Chromium build, 148.0.7778.96. Both are measured headful, the same night, through the same proxy. Two questions: what is different for a page that renders in each, and what does a site see — in particular when you put WebKit behind an iPhone device descriptor to stand in for an iPhone?

As a developer: driving them

	WebKit	Chromium
Version on the fleet	WebKit 26.4 (Playwright's build), one version.	Chromium 148.0.7778.96 (Playwright's build), one version.
Launch options	`screen_size`, `keep_alive`, `start_url` (headful), `profile`, `record`. No `cdp` and no `live_view`: headful sessions get a VNC live link, but WebKit ignores the viewer's clicks.	The same plus `cdp` (`connectOverCDP`, Puppeteer) and `live_view` (headless live view).
Playwright features	Main-world evaluate, console events, init scripts, routing, screenshots, device emulation and tracing work. `page.pdf()` fails: "PDF generation is only supported for Headless Chromium" (measured).	All of them, `page.pdf()` included — headful too (measured).
Web platform (newer CSS and APIs)	Has CSS `margin-trim`, CSS `random()`, `FontFace` width and WebTransport `reliability` — none of which Chromium 148 has (measured).	Has WebGPU, WebHID, the Topics API, Fenced Frames, Shared Storage, Protected Audience, Compression Dictionary transport and `requestStorageAccessFor` — none of which WebKit has (measured).
Cookies	Refuses every cookie on a domain listed in the Public Suffix List (httpbin.org is one) — case 57.	Keeps host-only cookies there.
Fulfilled responses	HTML served from `page.route` with only `charset=utf-8` in its Content-Type is decoded as Latin-1 — case 48.	Decoded as UTF-8.

As a scraper: what the site sees

	WebKit	Chromium
User agent	`Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.4 Safari/605.1.15` — a Mac, while `navigator.platform` says `Linux x86_64`.	`Mozilla/5.0 (X11; Linux x86_64) … Chrome/148.0.0.0 Safari/537.36` and `navigator.platform` `Linux x86_64` — they agree.
Client hints	None: no `navigator.userAgentData`.	Brands `Chromium 148`, `Not/A)Brand 99`; platform Linux, desktop.
`navigator.webdriver`	`true`.	`false`.
TLS	JA4 `t13d2914h1_723694b0fccc_067a5f92fbdb`: 29 ciphers, 14 extensions, and ALPN offers HTTP/1.1 only.	JA4 `t13d1516h2_8daaf6152771_d8a2da3f94cd`: 16 ciphers, 18 extensions, HTTP/2.
HTTP	HTTP/1.1 through the proxy, so no HTTP/2 fingerprint at all (case 01).	HTTP/2 with Chromium's SETTINGS (`1:65536;2:0;4:6291456;6:262144\|15663105`) and header order.
Vendor and WebGL	`navigator.vendor` "Apple Computer, Inc."; WebGL vendor "Apple Inc.", renderer "Apple GPU".	"Google Inc."; WebGL on SwiftShader (ANGLE, Vulkan).
Device signals	No `navigator.connection`, no `deviceMemory`.	`navigator.connection` and `deviceMemory` present.
Bot checks	bot.sannysoft.com runs 37 of its checks: 2 flags, "WebDriver (New)" and "Chrome (New)".	57 checks: 1 flag, "WebGL Renderer" (SwiftShader on a GPU-less server).

WebKit with an iPhone descriptor is not an iPhone's browser

With Playwright's devices['iPhone 15'] the page gets the iPhone user agent (iPhone OS 17_5 … Version/26.4 Mobile/15E148 Safari/604.1), a 393×659 viewport on a 393×852 screen, pixel ratio 3, ontouchstart and a coarse pointer (measured).
But navigator.platform stays Linux x86_64, navigator.maxTouchPoints is 0, navigator.webdriver is true, and navigator.standalone doesn't exist (measured). A script that checks any of these can tell it isn't a phone.
The same descriptor on Chromium also keeps Linux x86_64 and adds navigator.vendor "Google Inc." under that iPhone user agent, with one touch point — not a real phone either.
So use WebKit + a device descriptor for layout and rendering checks: how a page lays out, what CSS it gets, how the engine behind Apple's browser handles it. For a real iOS WebView, see iPhone.

Which to pick

Chromium for scraping: consistent identity, no webdriver flag, HTTP/2, CDP, and PDF.
WebKit for cross-browser testing — the engine and CSS behaviour behind Apple's browser, at a layout level, including mobile viewports with a device descriptor. Don't use it where a site checks for automation: its user agent and platform disagree and it reports navigator.webdriver.
Both cost the same: two threads headful, one headless.

Measured on the fleet (2026-10-18)

One headful launch of each through the same proxy, probed from inside a page and via tls.peet.ws.

Launch and cost

Single run; timings depend on the proxy and on fleet load.

	WebKit	Chromium
Launch body	{"headless":false}	{"headless":false}
Threads used	2 (linux_headful)	2 (linux_headful)
Browser version	26.4	148.0.7778.96
Launch request → browser ready	0.8 s	0.7 s
Playwright connect	0.1 s	0.1 s
Load example.com	6.2 s	1.0 s
Load tls.peet.ws/api/all	2.2 s	0.9 s

What the network sees

From tls.peet.ws/api/all, requested by the browser itself. JA3 hashes change between runs of the same build (GREASE), so compare JA4 and the HTTP/2 fingerprint.

	WebKit	Chromium
HTTP version	HTTP/1.1	h2
JA4	t13d2914h1_723694b0fccc_067a5f92fbdb	t13d1516h2_8daaf6152771_d8a2da3f94cd
Peetprint hash	bb44ee2f537184f8584269789ab7ffee	1d4ffe9b0e34acac0bd883fa7f79d7b5
Akamai HTTP/2 fingerprint	—	1:65536;2:0;4:6291456;6:262144\|15663105\|0\|m,a,s,p
Cipher suites / extensions	29 / 14	16 / 18
Header order (first 12)	—	method, authority, scheme, path, sec-ch-ua, sec-ch-ua-mobile, sec-ch-ua-platform, upgrade-insecure-requests, user-agent, accept, sec-fetch-site, sec-fetch-mode

What page scripts see

Read with page.evaluate on example.com. Cores and memory are the server's and vary between fleet nodes.

	WebKit	Chromium
navigator.userAgent	Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.4 Safari/605.1.15	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36
UA-CH brands	—	Not/A)Brand 99 · Chromium 148
UA-CH full version list	—	Not/A)Brand 99.0.0.0 · Chromium 148.0.7778.96
navigator.platform / vendor	Linux x86_64 / Apple Computer, Inc.	Linux x86_64 / Google Inc.
Languages	en-US	en-US
Timezone / locale	UTC / en-US	UTC / en-US
Screen (w×h×availW×availH×depth)	1280x720x1280x720x24	1280x720x1280x720x24
Window outer / inner / DPR	1280x758 / 1280x720 / 1	1288x805 / 1280x720 / 1
hardwareConcurrency / deviceMemory	8 / —	64 / 32
WebGL vendor	Apple Inc.	Google Inc. (Google)
WebGL renderer	Apple GPU	ANGLE (Google, Vulkan 1.3.0 (SwiftShader Device (Subzero) (0x0000C0DE)), SwiftShader driver)
WebGL version	WebGL 2.0	WebGL 2.0 (OpenGL ES 3.0 Chromium)
WebGPU (navigator.gpu)	no	yes
Canvas hash	25c86b3f	f5a94624
navigator.webdriver	yes	no
window.chrome / navigator.connection	no / no	yes / yes
Plugins / PDF viewer	5 / yes	5 / yes
Notification.permission / permissions.query	default / prompt	default / prompt

Web platform features

Presence probes; a user agent that claims one version while exposing another's features is a detectable inconsistency.

	WebKit	Chromium
`Iterator.prototype.includes` (new in Chrome 154)	no	no
`FontFace.width` (new in Chrome 154)	yes	no
CSS `text-decoration-inset` (new in Chrome 154)	no	no
`Iterator.prototype.join` (Chrome 153)	no	no
`Iterator.zip` (Chrome 153)	no	no
CSS `scroll-axis-lock` (Chrome 153)	no	no
`<camera>` element (Chrome 153)	no	no
`document.requestStorageAccessFor` (deprecated in 153)	no	yes
Topics API (`document.browsingTopics`)	no	yes
Protected Audience (`navigator.joinAdInterestGroup`)	no	yes
Shared Storage (`window.sharedStorage`)	no	yes
Attribution Reporting (`window.attributionReporting`)	no	no
Private Aggregation	no	no
WebHID (`navigator.hid`)	no	yes
CSS `margin-trim` (Chrome 155)	yes	no
CSS `text-decoration-skip-spaces` (Chrome 155)	no	no
CSS `corner` shorthand (Chrome 155)	no	no
CSS `symbols()` (Chrome 155)	no	no
`Element.streamAppendHTML` (Chrome 155)	no	no
`WebTransport.reliability` (Chrome 155)	yes	no
`window.maximize()` — Additional Windowing Controls (Chrome 155)	no	no
Canvas `srgb-linear` colour space (Chrome 155)	no	no
Permission policy `media-playback-while-not-visible` (Chrome 155)	no	no
CSS `random()` (Chrome 156)	yes	no
CSS `scroll-snap-type: pair` (Chrome 156)	no	no
Fenced frames (`window.fence`) — removal starts in 157	no	yes
`rel=compression-dictionary` (Chrome 156 updates)	no	yes

bot.sannysoft.com

The classic headless-detection test page; what it marks red.

	WebKit	Chromium
Checks / failed	37 / 2	57 / 1
Failed checks	WebDriver (New), Chrome (New)	WebGL Renderer

A plain-HTTP URL (http://ip-api.com/json)

Chrome 154 warns before loading insecure HTTP by default — does that reach an automated session?

	WebKit	Chromium
Final URL	http://ip-api.com/json/?fields=status	http://ip-api.com/json/?fields=status
HTTP status	200	200
Content loaded / warning page first	yes / no	yes / no

Playwright over the remote connection

Which client features work on this side.

	WebKit	Chromium
page.evaluate runs in the page's own world	yes	yes
addInitScript visible to page scripts	yes	yes
Console events	yes	yes
Request interception (page.route)	yes	yes
Screenshot	yes	yes
PDF	no — Error: page.pdf: PDF generation is only supported for Headless Chromium	yes
Mobile device emulation	yes	yes
Tracing	yes	yes

Rows where the two sides differ are highlighted. IP addresses are replaced with placeholders (203.0.113.x). The probe is compare/probe.mjs in our repository; the raw result is below.

Raw output

{
  "ran_at": "2026-10-18T01:03:40.639Z",
  "sides": [
    {
      "label": "WebKit",
      "engine": "webkit",
      "body": {
        "headless": false
      },
      "launch": {
        "browser": "webkit",
        "resource_class": "linux_headful",
        "weight": 2,
        "launch_ms": 752,
        "connect_ms": 63,
        "example_ms": 6229,
        "peet_ms": 2246
      },
      "network": {
        "http_version": "HTTP/1.1",
        "ja4": "t13d2914h1_723694b0fccc_067a5f92fbdb",
        "ja3_hash": "4ded71be9138938d71dbef4272be7708",
        "peetprint_hash": "bb44ee2f537184f8584269789ab7ffee",
        "ciphers": 29,
        "extensions": 14,
        "header_order": null
      },
      "page": {
        "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.4 Safari/605.1.15",
        "platform": "Linux x86_64",
        "vendor": "Apple Computer, Inc.",
        "languages": [
          "en-US"
        ],
        "hardware_concurrency": 8,
        "device_memory": null,
        "max_touch_points": 0,
        "webdriver": true,
        "plugins": 5,
        "pdf_viewer": true,
        "ua_data": null,
        "screen": "1280x720x1280x720x24",
        "window": {
          "outer": "1280x758",
          "inner": "1280x720",
          "dpr": 1
        },
        "timezone": "UTC",
        "locale": "en-US",
        "webgl": {
          "vendor": "Apple Inc.",
          "renderer": "Apple GPU",
          "version": "WebGL 2.0"
        },
        "canvas_hash": "25c86b3f",
        "webgpu": false,
        "chrome_object": false,
        "chrome_runtime": false,
        "notification_permission": "default",
        "notification_query": "prompt",
        "has_focus": true,
        "connection_api": false,
        "stack_read_by_debugger": false,
        "features": {
          "iterator_includes": false,
          "iterator_join": false,
          "iterator_zip": false,
          "fontface_width": true,
          "css_text_decoration_inset": false,
          "css_scroll_axis_lock": false,
          "websocket_options_bag": null,
          "camera_element": false,
          "topics_api": false,
          "protected_audience": false,
          "shared_storage": false,
          "attribution_reporting": false,
          "request_storage_access_for": false,
          "webhid": false,
          "private_aggregation": false,
          "css_margin_trim": true,
          "css_text_decoration_skip_spaces": false,
          "css_corner_shorthand": false,
          "css_symbols": false,
          "stream_append_html": false,
          "webtransport_reliability": true,
          "window_maximize": false,
          "canvas_srgb_linear": false,
          "policy_media_playback_while_not_visible": false,
          "css_random": true,
          "css_scroll_snap_pair": false,
          "fenced_frames": false,
          "compression_dictionary": false
        }
      },
      "page_main_world": null,
      "sannysoft": {
        "checks": 37,
        "failed": 2,
        "failed_names": [
          "WebDriver (New)",
          "Chrome (New)"
        ],
        "passed": 9
      },
      "plain_http": {
        "final_url": "http://ip-api.com/json/?fields=status",
        "status": 200,
        "title": "",
        "loaded": true,
        "warning_page": false,
        "page_text": "{\"status\":\"success\"}"
      },
      "playwright": {
        "evaluate_in_main_world": true,
        "console_events": true,
        "init_script": true,
        "route": true,
        "screenshot": true,
        "pdf": false,
        "pdf_error": "Error: page.pdf: PDF generation is only supported for Headless Chromium",
        "mobile_emulation": true,
        "tracing": true
      },
      "browser_version": "26.4"
    },
    {
      "label": "Chromium",
      "engine": "chromium",
      "body": {
        "headless": false
      },
      "launch": {
        "browser": "chromium",
        "resource_class": "linux_headful",
        "weight": 2,
        "launch_ms": 740,
        "connect_ms": 53,
        "example_ms": 1000,
        "peet_ms": 868
      },
      "network": {
        "http_version": "h2",
        "ja4": "t13d1516h2_8daaf6152771_d8a2da3f94cd",
        "ja3_hash": "22d4b0372811536f39e50c3823b66c25",
        "peetprint_hash": "1d4ffe9b0e34acac0bd883fa7f79d7b5",
        "ciphers": 16,
        "extensions": 18,
        "akamai_h2": "1:65536;2:0;4:6291456;6:262144|15663105|0|m,a,s,p",
        "akamai_h2_hash": "52d84b11737d980aef856699f885ca86",
        "header_order": [
          "method",
          "authority",
          "scheme",
          "path",
          "sec-ch-ua",
          "sec-ch-ua-mobile",
          "sec-ch-ua-platform",
          "upgrade-insecure-requests",
          "user-agent",
          "accept",
          "sec-fetch-site",
          "sec-fetch-mode"
        ]
      },
      "page": {
        "user_agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/148.0.0.0 Safari/537.36",
        "platform": "Linux x86_64",
        "vendor": "Google Inc.",
        "languages": [
          "en-US"
        ],
        "hardware_concurrency": 64,
        "device_memory": 32,
        "max_touch_points": 0,
        "webdriver": false,
        "plugins": 5,
        "pdf_viewer": true,
        "ua_data": {
          "brands": [
            {
              "brand": "Not/A)Brand",
              "version": "99"
            },
            {
              "brand": "Chromium",
              "version": "148"
            }
          ],
          "mobile": false,
          "platform": "Linux",
          "architecture": "x86",
          "bitness": "64",
          "formFactors": [
            "Desktop"
          ],
          "fullVersionList": [
            {
              "brand": "Not/A)Brand",
              "version": "99.0.0.0"
            },
            {
              "brand": "Chromium",
              "version": "148.0.7778.96"
            }
          ],
          "model": "",
          "platformVersion": "",
          "uaFullVersion": "148.0.7778.96",
          "wow64": false
        },
        "screen": "1280x720x1280x720x24",
        "window": {
          "outer": "1288x805",
          "inner": "1280x720",
          "dpr": 1
        },
        "timezone": "UTC",
        "locale": "en-US",
        "webgl": {
          "vendor": "Google Inc. (Google)",
          "renderer": "ANGLE (Google, Vulkan 1.3.0 (SwiftShader Device (Subzero) (0x0000C0DE)), SwiftShader driver)",
          "version": "WebGL 2.0 (OpenGL ES 3.0 Chromium)"
        },
        "canvas_hash": "f5a94624",
        "webgpu": true,
        "chrome_object": true,
        "chrome_runtime": false,
        "notification_permission": "default",
        "notification_query": "prompt",
        "has_focus": true,
        "connection_api": true,
        "stack_read_by_debugger": false,
        "features": {
          "iterator_includes": false,
          "iterator_join": false,
          "iterator_zip": false,
          "fontface_width": false,
          "css_text_decoration_inset": false,
          "css_scroll_axis_lock": false,
          "websocket_options_bag": null,
          "camera_element": false,
          "topics_api": true,
          "protected_audience": true,
          "shared_storage": true,
          "attribution_reporting": false,
          "request_storage_access_for": true,
          "webhid": true,
          "private_aggregation": false,
          "css_margin_trim": false,
          "css_text_decoration_skip_spaces": false,
          "css_corner_shorthand": false,
          "css_symbols": false,
          "stream_append_html": false,
          "webtransport_reliability": false,
          "window_maximize": false,
          "canvas_srgb_linear": false,
          "policy_media_playback_while_not_visible": false,
          "css_random": false,
          "css_scroll_snap_pair": false,
          "fenced_frames": true,
          "compression_dictionary": true
        }
      },
      "page_main_world": null,
      "sannysoft": {
        "checks": 57,
        "failed": 1,
        "failed_names": [
          "WebGL Renderer"
        ],
        "passed": 30
      },
      "plain_http": {
        "final_url": "http://ip-api.com/json/?fields=status",
        "status": 200,
        "title": "",
        "loaded": true,
        "warning_page": false,
        "page_text": "{\"status\":\"success\"}"
      },
      "playwright": {
        "evaluate_in_main_world": true,
        "console_events": true,
        "init_script": true,
        "route": true,
        "screenshot": true,
        "pdf": true,
        "mobile_emulation": true,
        "tracing": true
      },
      "browser_version": "148.0.7778.96"
    }
  ]
}

Bottom line

WebKit and Chromium differ in everything a site can measure: TLS and HTTP version, client hints, vendor, WebGL, the webdriver flag, and a different set of newer CSS and web APIs.

WebKit is the one to check layouts against the engine behind Apple's browser; it is not a stealth browser and not an iPhone.