JSON pad array to length

Client

Extend a JSON array to N rows with null padding—align batch sizes for chart grids, fixed-slot fixtures, and union steps without re-fetching data.

Learn more: JSON pad array length

Extend a JSON array to a target length by appending null (or documented padding values)—align batch sizes for charts, grids, and fixed-slot fixtures.

Target length

If the array is shorter than the target, padding rows are added. If it is already long enough, behavior follows the tool output—verify with the example before production fixtures.

Null padding

Null slots mark empty grid cells or placeholder rows. Downstream tools should treat null as missing data, not zero.

Privacy

Padding is applied locally to pasted JSON.

About JSON pad array to length

Extend a JSON array to N rows with null padding—local. Parsing and transforms run in your browser—Toolcore does not upload your JSON for this operation.

How to use

Paste a JSON array (or follow the two-array example on join tools). Use Load example when shown, or prefill with ?q= / ?qb= on the tool URL.

Input and limits

Fix JSON syntax errors before expecting output. Very large arrays may slow the tab—trim samples during exploration, then scale up locally.

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Nearby workflows on Toolcore

  • JSON formatter — JSON format online: pretty-print, minify, validate, escape, download . Useful once JSON parses on this page.
  • JSON replace values — Replace every value equal to from with to—use from|to, JSON or plain text. Useful once JSON parses on this page.
  • JSON filter field by regex — Keep rows whose string field matches a regular expression—local. Useful once JSON parses on this page.
  • JSON count field nulls — Count null or missing values for one row field—metadata. Useful once JSON parses on this page.

Common use cases

  • Extend short JSON arrays to a fixed slot count for chart or grid fixtures.
  • Align batch sizes before union or compare operations.
  • Add null placeholders for missing rows in test data.

Common mistakes to avoid

  • Target length smaller than current array

    Verify behavior when input already exceeds target—read output before relying on truncation rules.

  • Treating null padding as zero

    Null marks missing slots—downstream math should handle null explicitly.

  • Padding non-array JSON

    Input must be an array to extend with trailing elements.

FAQ

What value is used for padding?

Typically null for missing row slots—see tool output for the exact fill.

Is processing local?

Yes—padding runs in your browser.

Agent prefill?

Use ?q= / ?qb= for JSON; set target length on the page.

More tools

Related utilities you can open in another tab—mostly client-side.