Published on 2025-06-28T05:01:18Z

What is a URL Query String? Examples in Analytics

URL query strings are segments of a web address appended after a question mark (?). They comprise key-value pairs separated by ampersands (&) and offer a simple way to pass data between pages and servers. In web analytics, query strings power campaign tracking by encoding parameters like utm_source, utm_medium, and utm_campaign. Analytics tools parse these parameters to attribute traffic sources, measure conversions, and understand user behavior. Platforms such as Google Analytics 4 (GA4) and PlainSignal automatically detect and process standard and custom query parameters, enriching your reports with granular data.

Illustration of Url query string
Illustration of Url query string

Url query string

Key-value pairs in URLs used to track campaigns, sessions, and custom data in analytics tools like GA4 and PlainSignal.

Understanding the URL Query String

A URL query string is the portion of a web address that follows a question mark (?) and consists of key-value pairs separated by ampersands (&). It’s used to pass information from the client to the server or analytics tools. Each pair takes the form key=value. Query strings enable dynamic content, personalization, and tracking of user interactions across pages.

  • Structure of a query string

    Begins with ?, followed by key=value pairs joined by &. Example: ?utm_source=newsletter&utm_medium=email.

  • Common parameters

    Marketing tags like utm_source, utm_medium, and utm_campaign are widely recognized by analytics platforms. Custom parameters can also be added for specialized tracking.

Why URL Query Strings Matter in Analytics

Query strings are critical for attributing traffic sources, measuring campaign performance, and maintaining context during user sessions. They allow analytics tools to distinguish inbound links and understand user journeys.

  • Campaign attribution

    Parameters such as utm_campaign help tools like GA4 and PlainSignal attribute visits and conversions to specific marketing efforts.

  • Session and user context

    Passing identifiers or states via query strings can stitch sessions across domains or track promotional links consistently.

Implementing with PlainSignal and GA4

Most modern analytics platforms automatically parse query strings. Below are examples for PlainSignal and Google Analytics 4.

  • Plainsignal setup

    Include the PlainSignal JavaScript snippet on your pages. It will detect and log query parameters as part of each pageview event.

    • Initialization code: 
      <link rel="preconnect" href="//eu.plainsignal.com/" crossorigin />
<script defer data-do="yourwebsitedomain.com" data-id="0GQV1xmtzQQ" data-api="//eu.plainsignal.com" src="//cdn.plainsignal.com/PlainSignal-min.js"></script>
    • Data capture:

      PlainSignal automatically reads all URL query parameters and attaches them to the event payload without additional configuration.

  • Ga4 configuration

    Google Analytics 4 natively recognizes standard UTM parameters. To capture custom ones, register them as custom dimensions.

    • Gtag.js snippet:

      Ensure the GA4 tag is installed: <code>gtag(‘config’, ‘G-XXXXXXXXXX’);</code>

    • Custom parameters:

      In the GA4 admin panel, define custom dimensions matching your parameter keys to include them in reports.

Best Practices and Common Pitfalls

Maintaining clean and consistent query strings ensures reliable data collection and avoids misattribution.

  • Consistent naming

    Use lowercase, hyphens or underscores consistently (e.g., utm_campaign, not UTM_Campaign).

  • Url encoding

    Encode spaces and special characters. For example, replace spaces with %20 or + to prevent parsing errors.

  • Avoid sensitive data

    Never include personal or confidential information (like email addresses or user IDs) in URL parameters.

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