Why do real Chrome UAs look so cluttered?

Historical baggage — every browser has shipped UA strings starting with 'Mozilla/5.0' for compatibility since the late 90s, then layered on their own identifier. Cleaning this up is the goal of the Sec-CH-UA header set, but until adoption is universal, the long UA stays.

Can I generate Googlebot?

Yes — pick from the dropdown. The actual Googlebot UA changes occasionally (Google publishes the canonical version at developers.google.com/search/docs/crawling-indexing/overview-google-crawlers). The tool tracks the current value.

Will sites accept my custom UA?

Sites can detect spoofed UAs (TLS fingerprinting, HTTP/2 settings, JS behaviour). A custom UA is enough for simple feature-flag testing but won't fool sophisticated bot detection.

ua · chrome · firefox · safari · edge

Compose any User-Agent string

Q: Is anything sent to a server?

No — the UA is generated locally. You can use it however you want.

Generate a UA for Chrome, Firefox, Safari or Edge across Windows, macOS, Linux, Android, iOS. All template logic runs locally.

User-Agent Generator

Browser

chrome

engine

windows

platform

Version

120.0.0.0

string

Length

111 B

111 chars

input · platform

Version

output · user-agent

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Quick Start

How to compose a User-Agent

Pick the browser engine, OS, and version. The canonical template is filled in for you.

01
Pick browser
Chrome, Firefox, Safari, Edge. Each has a different signature.
Lookups reference the IANA registries (MIME, HTTP status, TLDs) bundled at build time — no live network calls, no rate limits, no leaked queries.
browserIANAregistryofflinelive
engine · querychrome · IANA
```
Chrome/120
```
loaded · IANA bundlespec · ready
02
Pick OS
Five platforms — Safari is mac/iOS only.
Builders emit canonical syntax per the relevant RFC (9110 for HTTP, 5322 for headers, 3986 for URLs) so the output passes spec-compliant parsers.
osRFC 9110canonicalspec-compliantlive
os · optionswindows · live
```
Windows NT 10.0
```
options applied · livecanonical
03
Set version
Any 3- or 4-part version string. Tip: stay close to the real current release.
Validation flags common pitfalls — uppercase header names, smart quotes inside Content-Type, missing ;charset=utf-8 — before they bite production.
versionvalidationlintpitfallslive
ver · looked up120.0.0.0 · ready
```
Chrome/120.0.0.0
```
result · livevalidated
04
Copy & use
Use in curl, your test harness, or to spoof during a smoke test.
Copy writes the snippet directly into your clipboard; downloads emit the right extension and MIME so curl/httpie pick them up correctly.
useclipboardMIME-correctblobcurl-ready
ok · copiedready · done
```
curl -A "Mozilla/5.0…"
```
shipped · ready to shipsuccess

Pro tips

Web-spec details that bite later

Idempotency saves retries

POST/PUT/DELETE should be safely retried. Use idempotency keys and return the same response on duplicate requests.

Match RFC 9110 status codes

Don’t invent codes. 422 for validation errors, 409 for conflicts, 429 for rate limits. Standard codes work with off-the-shelf clients.

Set <code>Cache-Control</code> deliberately

Default browser caching is conservative. Use max-age + stale-while-revalidate for hot endpoints.

Validate Open Graph in dev

OG tags break silently. Use a previewer like OG Generator + Facebook’s debugger before launch.

CORS is a server concern

The browser sends the preflight; the server decides. Wildcard origins disable credentials — be explicit.

MIME drives behaviour

Servers must send the right Content-Type. Browsers sniff but the spec says they shouldn’t — be explicit to avoid surprises.

Use Cases

When to compose a UA

Testing, integration, telemetry.

Browser testing

Spoof a UA when testing UA-sniffing code paths. Bundled from IANA registries at build time — no live network call, no rate limit, no leaked queries. The MIME, TLD, and status-code tables are baked in so the tool works offline once loaded.

spec-compliant

API constraints

Some APIs reject blank or curl UAs. Output is canonical per the relevant RFC (9110 for HTTP, 5322 for headers, 3986 for URLs), so spec-compliant parsers accept it as-is. Cross-browser and cross-library behaviour stays consistent.

offline

Smoke checks

Hit your site as if you were on iOS Safari. Pairs with the curl-to-fetch converter for end-to-end test stubs — copy the curl from DevTools, paste, get an idiomatic fetch() body. Drop into Playwright/Vitest fixtures without manual translation.

IANA-backed

Telemetry mocks

Test analytics parsing without spinning up a real browser. Catches common pitfalls (uppercase header names, smart quotes inside Content-Type, missing ;charset=utf-8) before they bite production. Validation flags rather than auto-corrects so you stay in control.

RFC-aligned

Crawler config

Identify your crawler with a clear, parseable UA. Validation runs as you type — copy only when the output is shaped correctly. The output drops directly into nginx, Apache, or CDN configs without re-formatting or re-quoting.

production-grade

Edge config

Tune CDN rules that key on UA tokens. Same input plus same options always produces identical canonical output, so the tool is safe to embed in CI scripts that diff against expected configs.

curl-ready

FAQ

Frequently asked questions

Why does Mozilla/5.0 prefix everything?

Historical: all browsers ship that prefix for compatibility with old UA sniffers.

Why no Internet Explorer?

IE is end-of-life. Use Edge in modern Chromium mode.

What about Client Hints?

Sec-CH-UA headers are the modern replacement. UAs still ship for compatibility but contain less detail.

Is spoofing UAs legal?

Generally yes for testing your own systems. Always respect rate limits and the target's terms.

Is anything sent to a server?

No — UA composition runs locally in your browser.

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