JSON Array Flattener
Flatten nested arrays inside JSON into a single flat array.
Collapsing arrays of arrays
Data sometimes arrives as arrays nested inside arrays — a list of lists, several levels deep — when what you want is one flat list of all the values. This flattens the nested arrays into a single array, pulling every element up to one level, so you can work with the values directly instead of looping through layers of nesting.
Paste JSON with nested arrays and it is flattened.
Depth and what gets flattened
Flattening can go one level or all the way down, and which you want depends on the data — sometimes you want to collapse everything into one list, sometimes only to unwrap a single layer. This targets array nesting specifically, distinct from flattening a nested object into dotted keys, which is a different job. It is handy for tidying up data that came grouped when you need it ungrouped, combining results that arrived in batches, or simplifying a structure before processing the values one by one.
Common questions
What does it flatten?
Nested arrays — arrays inside arrays — collapsed into a single flat array of values.
How is this different from flattening an object?
This targets array nesting; flattening an object collapses nested keys into a dotted single level, a different job.
Is my JSON uploaded?
No. The flattening happens in your browser.