JSON Array to Repeated Query Parameters – Build Duplicate Keys

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Show how Build Query maps arrays of primitive JSON values to repeated URLSearchParams keys.

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Query string build behavior

How JSON arrays become repeated query parameters

Build Query uses one query pair per array item. A JSON array property therefore becomes repeated keys such as tag=json&tag=tools instead of a comma-joined string. This tool is free to use. No account or payment is required.

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What you can do here

  • Browser-native URLSearchParams behavior
  • Full URL and raw query parsing
  • Repeated parameter preservation
  • JSON object to query construction
  • Browser-local processing

Steps

  1. Switch to Build Query.
  2. Use an array of primitive values for the property that should repeat.
  3. Copy the generated query and confirm the receiver accepts repeated-key semantics.

Arrays map to append(), not comma joining

The builder appends each primitive array item separately to URLSearchParams. It does not invent comma-separated or bracket notation.

That keeps the output symmetrical with Parse mode, which groups repeated keys into ordered JSON arrays.

Array values become repeated tag parameters

Two array items produce two tag pairs.

JSON object

{"tag":["json","tools"],"sort":"asc"}

Built query string

tag=json&tag=tools&sort=asc

Common questions

Frequently asked questions

Are arrays joined with commas?

No. Each primitive array item becomes another parameter with the same key.

Is array order preserved?

Yes. Values are appended in JSON array order.

Can array items be objects?

No. Build Query accepts primitives or arrays of primitives only.

Recommended next steps

Repeated Query ParametersSee how repeated keys become ordered JSON arrays instead of overwriting values.Query String Parser & Builder OnlineParse a URL or raw query into JSON, or build query parameters from JSON.JSON Formatter OnlineValidate and format JSON before using it in Build Query mode.

Debugging a specific Query String issue? Browse Query String troubleshooting.