Record-path selection
Candidate arrays are listed so you decide which JSON objects should become CSV rows.
Nested JSON to CSV without silent number rounding
JSON to CSV Converter for Nested Data and Long IDs
Convert JSON to CSV locally with record-path selection, explicit array handling, duplicate-key checks, lossless long integers, and spreadsheet formula protection before download.
✓ Runs locally✓ No account✓ Free first release
Start with the exampleLocal browser processingYour file contents are not uploaded.
10 MB · 50,000 row limitConversion workbench
Inspect first. Export second.
Source structure, quality findings, and every deliberate transformation stay visible before download.
1
Source data
Paste JSON or upload a JSON file
or drop it here
2
Structure choices
Nothing ambiguous is hidden behind “auto.”
Blank CSV field boundaryJSON null, a missing property, and an empty string remain distinct in the preview, but CSV exports all three as a blank field.
CSV export settings
3
Preview and quality report
Analyze the sample or your own data to continue.
Your source data is still only in this browser.
Analysis creates a table preview, a ranked issue list, and an exact transformation summary.
Private by design
Source bytes remain in this browser tab.
Reviewable
Preview values and risks before export.
Traceable
Download a JSON conversion report.
What the converter checks
Quality findings belong beside the output
A successful parse is not proof that the result kept the source meaning. These checks surface the places where tabular conversion can change or hide data.
Lossless numeric parsing
Long JSON integer text is retained exactly instead of being rounded by native number parsing.
Explicit array handling
Keep arrays as JSON, join scalar arrays, or expand one selected array—never an implicit multi-array Cartesian product.
Duplicate-key and formula checks
Duplicate JSON object keys block export, while formula-like CSV values are counted and escaped by default.
Preservation rules
Know what happens to difficult values
The tool records deliberate changes and keeps ambiguous structures visible rather than silently normalizing them.
Read the full check definitions →Source featureConverter behavior
Long integer IDs
Every source digit is retained in the CSV text; no JavaScript number rounding is introduced.
Nested objects
Flattened into escaped path columns such as profile.name.
Nested arrays
Stored as JSON text by default; at most one chosen array can be expanded into rows.
Formula-like strings
Escaped by default for safer spreadsheet opening, with every changed cell reported.
Null, missing, and empty strings
Distinct in the preview, but all become blank CSV fields because CSV has no native null or missing-value type.
A short, inspectable workflow
From source to checked CSV
- 1
Add the JSON
Paste a document or choose a local JSON file. Parsing stays inside this browser tab.
- 2
Choose rows and arrays
Confirm the record path and how any nested array should be represented.
- 3
Inspect and download CSV
Review long IDs, blank-value semantics, formula risks, and transformations before export.
A concrete failure mode
Why a successful JSON parse is not enough for CSV
A 19-digit ID can be rounded before export, two nested arrays can multiply rows, and null, a missing property, and an empty string all collapse to a blank CSV field. The preview makes those boundaries visible before download.
Inspect the included example