Guzzle PHP HTTP client user agent
Guzzle is a widely used PHP HTTP client. Its default user agent contains a GuzzleHttp token together with a version and language details, so default-configured Guzzle traffic is easy to spot. Many PHP applications override it, so the token is a strong-but-optional signal. It is server-side automation, not a human visit.
What this means
Guzzle is a PHP library for making HTTP requests, used heavily for API integrations, server-to-server calls, and some scraping. By default it sends a user agent containing the GuzzleHttp token, a version, and runtime details such as the PHP and cURL versions.
That default identifies the library plainly. But applications frequently set their own user agent (an app name, or a browser-like string), so a large share of Guzzle-driven requests do not show the token.
How Guzzle identifies itself
Guzzle's default user agent contains the GuzzleHttp token and version. Match on the GuzzleHttp token substring rather than a fixed version. Guzzle documents the default header and how to override it.
Because the header is trivially changed, treat the token as a strong but optional signal. Its absence does not rule out Guzzle; many integrations rebrand or hide it.
- Default user agent contains the GuzzleHttp token plus version
- Often includes PHP / cURL runtime details
- Header is commonly overridden by the application
Interpreting Guzzle traffic
Default Guzzle traffic is usually benign server-side integration — webhooks, API polling, content fetchers — but can also be scraping. Judge intent by what it requests and how often, not by the library name.
When the user agent is customised, identify the underlying client by request shape: no browser headers, no asset or JavaScript loading, and machine-like cadence. These cues distinguish HTTP-library traffic from real browsers.
How it appears in analytics and logs
A request whose user agent contains the GuzzleHttp token is a PHP application using Guzzle with its default UA. Because the header is commonly customised, much Guzzle traffic arrives under an app-specific or browser-like user agent.
Diagnostic use case
Identify default Guzzle traffic in logs — often from PHP apps, integrations, or scrapers — and understand why the token is frequently replaced.
What WebmasterID can help detect
WebmasterID classifies the default GuzzleHttp token server-side as automation and surfaces it on the bot-intelligence view, while noting that overridden user agents need request-shape signals to catch.
Common mistakes
- Assuming all Guzzle traffic carries the GuzzleHttp token — it is often overridden.
- Counting Guzzle integration requests as human visits.
- Treating default-UA Guzzle as inherently malicious; it is usually integration traffic.
Privacy and accuracy notes
Guzzle detection uses only the user agent and request shape. No human identity is involved — it is server-side code. WebmasterID records it as a bot/automation event, separate from human analytics.
Frequently asked questions
- Is GuzzleHttp traffic a bot?
- It is automated server-side code, so for analytics it is bot/non-human traffic. Whether it is welcome depends on intent — many cases are legitimate API or webhook integrations.
Related pages
- curl, wget and script user agents
Command-line and library HTTP clients send a default user agent that names the tool: curl/x.y, Wget, python-requests, Go-http-client, and similar. These are scripts, not browsers, and seeing them is normal. This page explains the patterns and how to treat them without over- or under-reacting.
- WordPress and CMS user agents
WordPress and other content systems generate server-side HTTP requests that carry their own user agents — notably WordPress pingback requests and loopback calls the site makes to itself. These can look like external bots in logs but are often your own CMS. This page explains the patterns so you read them correctly.
- API client user agents (Postman, etc.)
Developers exercise APIs with tools like Postman, Insomnia, and HTTPie, each of which sends a recognisable default user agent (for example a PostmanRuntime token). Seeing these means someone is testing or scripting against your API, not browsing your pages. This page covers the patterns and how to read them.
- Bot intelligence
Server-side classification of HTTP-library and integration traffic.
Sources and verification notes
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.