Query String Builder– Build URL Query Strings Online

Build URL query strings from key-value pairs instantly. Free online query builder.

Parameters (key-value pairs)

Generated Query String

Generated query string will appear here

Why Use Our Query String Builder?

Visual Builder

Add parameters visually with key-value inputs instead of typing raw strings.

Auto Encoding

Special characters are automatically URL-encoded for safe use.

Instant Build

Generate query strings instantly in your browser.

Dynamic Params

Add and remove parameters dynamically with one click.

One-Click Copy

Copy the generated query string to clipboard instantly.

Free Forever

No signup, no limits, no premium tiers. Build freely.

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Complete Query String Guide

A URL query string is the portion of a URL that follows the question mark (?) character. It consists of one or more key-value pairs, separated by ampersands (&), where each pair has the format key=value. Query strings are the primary mechanism for passing parameters to web pages and API endpoints through the URL.

For example, in the URL https://example.com/search?q=react&page=2&sort=date, the query string is ?q=react&page=2&sort=date with three parameters: q (search query), page (pagination), and sort (sorting criterion).

Query strings are used extensively in web development for search functionality, filtering results, pagination, tracking parameters (UTM codes), authentication tokens, and many other purposes. They are visible in the browser's address bar and can be bookmarked, shared, and cached independently.

Our builder tool provides a visual interface for constructing query strings. Instead of manually typing and encoding parameters, you can add key-value pairs through input fields. The tool automatically handles URL encoding of special characters, ensuring the output is safe to use in any URL.

Query string parameters must be properly encoded to ensure they are transmitted correctly. The encoding process has two aspects: encoding individual values and encoding the overall structure. Special characters in parameter names or values must be percent-encoded so they are not confused with structural characters like & (parameter separator) and = (key-value separator).

Our tool uses the JavaScript URLSearchParams API, which is the standard way to construct query strings in modern JavaScript. This API automatically handles encoding: spaces become + (per application/x-www-form-urlencoded), and other special characters are percent-encoded.

For example, a parameter with key "search" and value "price > 100 & category = shoes" would be encoded as search=price+%3E+100+%26+category+%3D+shoes. The >, &, and = characters in the value are encoded to prevent confusion with URL delimiters, while spaces become + signs.

Empty keys are filtered out by our builder to avoid producing malformed query strings. Empty values are kept since some APIs use parameter presence (without a value) as a boolean flag. The generated output includes the leading ? character, ready to append to any base URL.

API Endpoints

Build query strings for REST API calls with filters, pagination, sorting, and search parameters.

UTM Tracking

Create marketing URLs with utm_source, utm_medium, utm_campaign, and other tracking parameters.

Search URLs

Build search engine-style URLs with query terms, filters, page numbers, and result counts.

OAuth Redirects

Build OAuth authorization URLs with client_id, redirect_uri, scope, and state parameters.

What is a query string?

A query string is the part of a URL after the question mark (?) that contains key-value pairs separated by ampersands (&). For example, ?name=John&age=30. Query strings pass parameters to web pages and APIs.

How do I build a query string online?

Add key-value pairs using the input fields, then click 'Build'. The tool generates a properly encoded query string with all special characters escaped, ready to append to any URL.

Are special characters automatically encoded?

Yes, the builder uses URLSearchParams which automatically encodes special characters. Spaces become +, ampersands become %26, and other special characters are percent-encoded to ensure URL safety.

Can I add multiple parameters with the same key?

Yes, you can add multiple parameters with the same key name. This is common in APIs that accept arrays, producing query strings like ?color=red&color=blue.

What is the maximum length of a query string?

While there is no official limit in the URL standard, browsers and servers typically support query strings up to 2048-8192 characters. Very long query strings should be sent as POST request bodies instead.

Does the order of parameters matter?

In most cases, the order of query parameters does not matter to the server. However, some APIs or caching systems may treat different parameter orders as different URLs. Our builder preserves the order you specify.

How do I add or remove parameters?

Click the '+' button to add a new empty parameter row. Click the trash icon next to any parameter to remove it. You can add as many parameters as you need.

Is my data secure?

Yes, all query string building happens in your browser. Your parameter names and values are never sent to any server.

What is URL encoding in query strings?

URL encoding (percent-encoding) converts special characters to safe representations. For example, a space becomes + or %20, an ampersand becomes %26, and an equals sign becomes %3D. This prevents confusion with query string delimiters.

Can I use this for API testing?

Yes, this tool is perfect for building query strings for REST API endpoints. Add your parameters, build the string, and append it to your API base URL for testing.

Is this tool free?

Yes, completely free with no signup, no limits, and no restrictions. Build as many query strings as you need.

Query String Builder Tool

Why Use Our Query String Builder?

Other Encoding Tools

Complete Query String Guide