> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apostate.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Personas
> What a persona is, the three platforms, the default on each host, and every value a persona sets with where it comes from.
A persona is the operating system a launch presents to web pages: Windows, macOS or Linux. From the persona and a [seed](/concepts/seeds-and-identity), the browser composes one machine of that kind, with an OS release, a GPU, cores and memory, a screen, fonts, voices, audio and media devices. The Chromium code that produces each value serves the machine's value, so the page, its workers, its iframes and the HTTP headers all read the same machine.
## Choose a persona
```python Python theme={null}
from apostate import launch
browser = launch(fingerprint=42, fingerprint_platform="macos")
```
```javascript Node theme={null}
import { launch } from "@heretic-tech/apostate";
const browser = await launch({ fingerprint: 42, fingerprintPlatform: "macos" });
```
The browser switch is `--fingerprint-platform=windows`, `macos` or `linux`. The packages refuse any other value. The browser logs an error for any other value and uses the default persona.
## The default persona
When you name no persona, the browser picks one from the host:
| Host | Persona |
| ------- | ------- |
| macOS | macOS |
| Windows | Windows |
| Linux | Windows |
A Windows persona on a Linux or macOS host needs the Windows fonts installed there. [Fonts](/guides/fonts) has the command.
Name the persona in every launch of a persistent profile you move between hosts. A directory created on a Mac and opened on a Linux server without `fingerprint_platform` presents a macOS machine on the Mac and a Windows machine on the server.
## The three platforms
Each platform draws from its own tables. The counts are those of catalogue version 2, the one in Apostate 0.4.3.
| | Windows | macOS | Linux |
| ------------- | ------------------------------------------------------------------ | --------------------------------------------------------------------------------------------- | ---------------------------------------------- |
| OS releases | Windows 11 (two releases), Windows 10 22H2 | macOS 26.6.2, 26.5.0, 15.7.2 | Linux x86-64 |
| GPU families | NVIDIA Direct3D 11 (45 models), Intel Direct3D 11 (12 models) | Apple Metal (12 models, M1 to M4) | NVIDIA Vulkan (11 models) |
| Machines | desktop tower, small desktop, 15-inch laptop | MacBook Air, MacBook Pro, Mac mini, Mac Studio | desktop tower |
| Screens | 1280x720 to 3440x1440, pixel ratio 1 to 1.5, taskbar at the bottom | each Mac's built-in display, Studio Display, external 1080p and 1440p, with menu bar and Dock | 1920x1080 to 3840x2160, GNOME, KDE or no panel |
| Font families | 86 to 90 | 184 | 9, plus 4 from an optional Ubuntu pack |
| Voices | 22, from a US or UK English install | 199 | 19 network voices |
| Audio buffer | 480 frames | 256 frames | 512 frames |
[GPU models](/reference/gpu-models) and [Font lists](/reference/font-lists) list every model and family.
## What a persona sets
The browser's C++ serves every row, so every API and header that reads the value agrees. The section column names the part of the [profile](/reference/profile-schema) that carries it.
| What a page reads | Section | Where the value comes from |
| ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `navigator.userAgent`, the `User-Agent` header | `browser` | The OS release table. The version reads `Chrome/152.0.0.0`, as in Chrome's reduced User-Agent. |
| `navigator.platform` | `platform` | The OS release table: `Win32`, `MacIntel` or `Linux x86_64`. |
| `navigator.userAgentData`, `Sec-CH-UA-Platform`, `-Platform-Version`, `-Arch`, `-Bitness`, `-Model`, `-Form-Factors`, `-WoW64` | `platform` | The OS release table. Windows and Linux personas report the host's CPU architecture (`x86` or `arm`, see [ARM hosts](/concepts/hosts#arm-hosts)). macOS personas report `arm`. The brand list and full version are the build's own, with the `Google Chrome` brand. |
| `navigator.hardwareConcurrency`, `navigator.cpuPerformance`, the browser's own thread pools | `cpu` | The core-count table, one list per GPU model. Never more than the host has. |
| `navigator.deviceMemory`, the `Device-Memory` header, the heap limit in `performance.memory` | `memory` | The memory table, one list per GPU model. Never more than the host has. |
| WebGL `UNMASKED_VENDOR_WEBGL`, `UNMASKED_RENDERER_WEBGL` | `gpu` | The GPU model table, within the GPU family. |
| WebGL `getParameter()` limits such as `MAX_TEXTURE_SIZE`, `getSupportedExtensions()`, `getShaderPrecisionFormat()` | `gl_limits`, `gl_extensions`, `gl_precisions` | The GPU family, measured on real hardware. |
| WebGPU `requestAdapter()`: `info.vendor`, `info.architecture`, subgroup sizes, `features`, `limits` | `webgpu` | The GPU family. The architecture and subgroup sizes follow the model. On Linux, `requestAdapter()` returns `null` in headless mode and as root ([Known gaps](/known-gaps#webgpu-in-headless-mode-on-linux)). |
| `screen.width`, `height`, `availWidth`, `availHeight`, `availLeft`, `availTop`, `devicePixelRatio`, `colorDepth`, `screen.isExtended`, the `color-gamut` and `dynamic-range` media queries | `screen` | The screen table, one list per machine, and the taskbar, menu bar or panel table, one list per OS release. |
| Where a new window opens and how large it is | `screen` | The persona's work area. A Windows persona opens maximized. |
| Text measured in canvas or CSS, `@font-face local()`, `queryLocalFonts()` | `fonts` | The font pack table, one list per OS release. Only families installed on the host can appear. `document.fonts.check()` returns true for any family name, installed or not, so it does not show the list. |
| `system-ui`, the CSS system font keywords such as `font: menu`, text with no `font-family` | none | The persona's platform. `system-ui` is `Segoe UI` for Windows and `DejaVu Sans` for Linux. A macOS persona keeps the build's own `system-ui`. |
| `prefers-color-scheme`, CSS system colours such as `Highlight` and `ButtonFace` | `theme` | Light or dark, drawn by seed. The colours are the persona's platform defaults. The 0.4.3 packages let Playwright and Patchright emulate light, and from 0.4.4 they turn that emulation off ([Known gaps](/known-gaps#prefers-color-scheme-in-the-0-4-3-packages)). |
| `speechSynthesis.getVoices()` | `speech` | The voice table, one list per OS release and language. US and UK English have measured lists; any other language gets the US list. |
| `AudioContext.baseLatency`, `AudioContext.sampleRate` | `audio` | The platform's output buffer size. Every persona runs at 48 kHz. |
| `navigator.mediaDevices.enumerateDevices()` | `media` | The device table, one list per machine, with cameras, microphones and speakers and their labels. The host's own devices are listed too ([Known gaps](/known-gaps#cameras-and-microphones)). |
| `MediaCapabilities` `powerEfficient` | none | The persona's GPU. |
| `navigator.keyboard.getLayoutMap()` | none | The US layout of the persona's platform. A profile you write can carry another in `keyboard.layout_map`. |
| `navigator.connection` (`effectiveType`, `rtt`, `downlink`, `saveData`), the `ECT`, `RTT`, `Downlink` and `Save-Data` headers | `network` | One of three 4G connections. |
| `navigator.getBattery()` | `battery` | The battery table, one list per machine. Desktops report no battery, as desktop Chrome does. |
| `chrome.runtime` on web pages | `extensions` | Drawn by seed. A quarter of seeds show it, as on a Chrome with an extension that talks to web pages. |
| `navigator.share()`, `navigator.canShare()` | none | Present for Windows and macOS personas. |
| `new URL("c:/foo").protocol` and other Windows path forms | none | A Windows persona parses them as Windows Chrome does (`file:`). |
| Timezone, `Intl` defaults, `navigator.language`, `navigator.languages`, `Accept-Language` | `locale` | Not the seed. The packages take them from the proxy's location, or from your `locale` and `timezone` options. See [Locale and timezone](/guides/locale-and-timezone). |
| The `pointer` and `hover` media queries | `input` | Only a [profile you write](/guides/custom-profiles) sets them. Otherwise they are the host's, or a mouse under Playwright and Patchright in headless mode. |
The browser composes the machine in a fixed order, and later choices depend on earlier ones. The core count and memory depend on the GPU model, and the screen, devices and battery depend on the machine, so a persona never pairs, for example, an Apple M4 Max with a MacBook Air screen. [How it works](/concepts/how-it-works) has the order.
## Read a persona
`--fingerprint-explain` prints the machine a launch would present and exits without opening a window. These are seed 42 for each platform, run on an Apple silicon Mac with 14 cores. On another host, the core count and memory can differ; [Seeds and identity](/concepts/seeds-and-identity#the-host-cap) explains why.
```bash theme={null}
apostate run -- --fingerprint=42 --fingerprint-platform=windows --fingerprint-explain
```
```text theme={null}
surface layer evidence value
anchor anchor physical-ground-truth windows-d3d11-intel-79dfeb5b4f99
os_release dispersion physical-ground-truth windows-11
gpu_identity dispersion catalogue-value d3d11-intel-uhd-graphics-770-4680
webgpu anchor physical-ground-truth Intel(R) UHD Graphics 770
machine_class dispersion catalogue-value win-sff-desktop
cpu dispersion public-corpus cores-12
memory dispersion catalogue-value gib-8
panel dispersion public-corpus fhd-1080p
furniture dispersion physical-ground-truth taskbar-bottom
font_packs/platform-core dispersion catalogue-value core
media_topology dispersion catalogue-value desktop-speakers-only
audio dispersion physical-ground-truth wasapi-shared-480
network dispersion catalogue-value 4g-fast
battery dispersion catalogue-value absent
locale.application composed-default native-derived en-US
locale.accept_languages composed-default native-derived (the en-US bundle's default)
locale.timezone host-inherited host-inherited (inherited)
voices dispersion physical-ground-truth windows-en-us
extensions dispersion physical-ground-truth absent
theme dispersion catalogue-value dark
```
```text theme={null}
surface layer evidence value
anchor anchor physical-ground-truth macos-metal-apple-850a91233555
os_release dispersion catalogue-value macos-26-5-0
gpu_identity dispersion physical-ground-truth metal-apple-m4-max
webgpu anchor physical-ground-truth m4-max-chrome
machine_class dispersion catalogue-value mac-mbp14-studio-display
cpu dispersion physical-ground-truth cores-14
memory dispersion catalogue-value gib-36
panel dispersion catalogue-value studio-display
furniture dispersion catalogue-value menubar-dock-autohide
font_packs/platform-core dispersion physical-ground-truth core
media_topology dispersion catalogue-value mbp-studio-display
audio dispersion physical-ground-truth coreaudio-256
network dispersion catalogue-value 4g-typical
battery dispersion catalogue-value discharging-high
locale.application composed-default native-derived en-US
locale.accept_languages composed-default native-derived (the en-US bundle's default)
locale.timezone host-inherited host-inherited (inherited)
voices dispersion physical-ground-truth macos-bundled
extensions dispersion physical-ground-truth absent
theme dispersion catalogue-value light
```
```text theme={null}
surface layer evidence value
anchor anchor physical-ground-truth linux-vulkan-nvidia-adf287b8f0ee
os_release dispersion physical-ground-truth linux-x86-64
gpu_identity dispersion physical-ground-truth vulkan-nvidia-geforce-rtx-4070-ti-super
webgpu anchor physical-ground-truth REAL-nvidia-4070ti-linux
machine_class dispersion catalogue-value linux-desktop-tower
cpu dispersion catalogue-value cores-12
memory dispersion catalogue-value gib-32
panel dispersion catalogue-value uhd-2160
furniture dispersion physical-ground-truth gnome-topbar
font_packs/platform-core dispersion physical-ground-truth core
font_packs/ubuntu-desktop dispersion catalogue-value included
media_topology dispersion catalogue-value pulse-hdmi-desktop
audio dispersion catalogue-value pulse-512
network dispersion catalogue-value 4g-typical
battery dispersion catalogue-value absent
locale.application composed-default native-derived en-US
locale.accept_languages composed-default native-derived (the en-US bundle's default)
locale.timezone host-inherited host-inherited (inherited)
voices dispersion physical-ground-truth linux-none
extensions dispersion physical-ground-truth absent
theme dispersion catalogue-value light
```
The report also prints a header with the seed and the host, notes under the locale rows, and a `limitations` list. [Seeds and identity](/concepts/seeds-and-identity#read-the-seed-lines) explains the header.
The `layer` column says which step chose the value:
| Layer | Meaning |
| ------------------ | ----------------------------------------------------- |
| `anchor` | Taken from the GPU family as a whole. |
| `dispersion` | Drawn by seed from a table of options. |
| `command-line` | Set by a switch, such as `--fingerprint-locale`. |
| `composed-default` | No switch named it, so the persona's default applies. |
| `host-inherited` | Left to the host. |
The `evidence` column says where the option came from:
| Evidence | Meaning |
| ----------------------- | -------------------------------------------------------------------- |
| `physical-ground-truth` | Measured on a real machine this project captured. |
| `public-corpus` | Weighted from a public collection of real browser sessions. |
| `catalogue-value` | Written from vendor specifications and platform rules, not measured. |
| `compatibility-capture` | Measured on a host with no GPU. Only the SwiftShader family has it. |
| `native-derived` | Produced by the build itself. |
| `operator` | Set by you, or by the packages from GeoIP. |
| `host-inherited` | The host's own value. |
## What stays the host's
A persona changes values. It does not change how the host draws or computes. Canvas, WebGL and WebGPU pixels come from the host's GPU or software renderer, text is drawn by the host's font engine, a font appears only if it is installed, and CPU arithmetic and audio output follow the host's CPU. [Hosts](/concepts/hosts) says which host suits which persona, and [Known gaps](/known-gaps) lists every value a page can still read from the host.
## Host mode
`--fingerprint=host`, or `fingerprint="host"` in the packages, composes nothing. Every value is the host's own. `off`, `false`, `0`, `disable` and `disabled` mean the same, in any case. Use host mode to tell whether a problem comes from the persona or from the host and network under it.
Host mode refuses a persona, a GPU family and every per-field switch, because nothing is composed for them to change:
```text theme={null}
apostate: --fingerprint names an off value, so no profile is composed and --fingerprint-platform cannot take effect. Drop one of the two: --fingerprint=off for this machine's real fingerprint, or a seed for a composed one. --fingerprint-explain still works with either.
```
The packages refuse the same combination before the browser starts, with `host inheritance disables every layer below it, so a platform persona cannot be applied at the same time`.
Headless host mode has no display to inherit, so a page reads Chrome's headless 800x600 screen with `availHeight` equal to `height`. A composed persona serves its own screen in headless mode.