Crate ua 

ua — User-Agent generation and browser detection utilities.

This crate helps you build realistic User-Agent strings by detecting installed browsers and (when possible) using the detected browser version. It is designed for HTTP clients, automation tools, and apps that need browser-like headers.

Main API

Most users only need:

• build_user_agent to generate a UA string.
• UaStrictness to choose between strict vs resilient behavior.

If you want more control, you can use:

• platform_info to inspect the platform token inputs.
• detect_browsers to list installed browsers.
• choose_best_browser to override selection logic.

What it does

• Detects platform information: OS family and CPU architecture.
• Detects installed browsers (best-effort, OS-specific):
  • Windows: checks common install paths and reads .exe file version metadata.
  • macOS: checks /Applications/*.app and reads Info.plist version metadata.
  • Linux: checks PATH binaries and optionally inspects Flatpak/Snap installs.
• Generates browser-like User-Agent strings for:
  • Chromium family: Chrome / Edge / Chromium / Brave / Opera
  • Firefox
  • Safari (best-effort only)

Strictness

The UaStrictness mode controls how strict UA generation is:

• UaStrictness::Real:
  • Requires a detected browser and a parseable version.
  • Supported for Chromium-family and Firefox.
  • Safari is not supported in Real mode because Safari’s WebKit token mapping is not reliably derivable from the installed version alone.
• UaStrictness::BestEffort:
  • Produces a reasonable UA even when version detection is incomplete.
  • Recommended when you need resilience across varied machines.

Non-goals

• This crate does not attempt full browser fingerprint emulation. For more browser-like behavior, also consider sending UA-CH and Sec-Fetch headers.

Example

use ua::{build_user_agent, UaStrictness};
let ua = build_user_agent(UaStrictness::BestEffort)?;
println!("{ua}");

Notes on privacy and ethics

Browser-like headers can be used to reduce false blocks in legitimate automation, but also can be used for deceptive fingerprinting. Use responsibly and comply with applicable terms and policies.

Structs

BrowserInfo

Information about a detected browser installation.

PlatformInfo

Platform information used to build the UA platform token.

SemVerish

Parsed “version-like” representation extracted from browser version strings.

Enums

AgentError

Errors returned by platform/browser detection and UA generation.

Arch

CPU architecture classification for UA platform tokens.

BrowserKind

Browser families supported for UA generation.

OsFamily

High-level OS family used for UA platform tokens.

UaStrictness

Controls how strictly the generated UA must match a detected browser installation.

Functions

build_user_agent

Build a User-Agent string using installed browser detection and the requested strictness.

choose_best_browser

Choose the “best” browser from a detected list, using OS-specific preference ordering.

detect_browsers

Detect installed browsers on the current OS.

platform_info

Collect platform information used for UA generation.