Data tools, with explicit rules.
Move tables between CSV and JSON without uploading data or guessing field types.
Start with the file converter or open a tool below. CSV/TSV and JSON extensions suggest a destination; full validation happens in that tool.
| Source and goal | Tool | Mapping to review |
|---|---|---|
| Delimited table to object array | CSV to JSON | Values stay strings, preserving IDs and leading zeros. Choose the delimiter and header mode. |
| Flat object array to table | JSON to CSV | All fields are merged. Number text is preserved; null and missing fields become empty cells. Review formula protection. |
CSV to JSON
Convert delimited UTF-8 tables to JSON object arrays. Preserve values as strings, select a header mode and delimiter, and download individual files or a ZIP.
JSON to CSV
Convert flat JSON object arrays to CSV. Preserve number text, merge all columns, adjust their order and use visible formula protection for spreadsheet imports.
CSV is a table, not a typed database
CSV carries text fields and separators. A spreadsheet may infer dates or numbers when opening it, but those guesses are not part of the CSV format. CSV to JSON preserves every value as a string. JSON to CSV preserves numeric tokens in the output bytes, while JSON types and the distinction between null, a missing key and an empty value cannot be retained in an ordinary CSV table.
Use flat data and explicit settings
Choose comma, semicolon, tab or pipe. UTF-8 input with or without a BOM is supported. JSON input must be a top-level array of flat objects. Nested objects and arrays, duplicate keys, empty headers and inconsistent CSV field counts produce errors; these tools do not silently flatten or drop data. Column order can be adjusted after JSON-to-CSV conversion and applied by converting again.
Review spreadsheet formula protection
JSON to CSV defaults to prefixing potentially dangerous cells with an apostrophe and reports the number changed. The prefix changes the data and can affect downstream imports. Protection is not universal across spreadsheet applications or subsequent saves. Import untrusted data as text, inspect the receiving application and keep your original JSON.
Keep batches within device limits
Use up to 10 files, 5 MB per file and 20 MB total. Each input produces its own output; ZIP downloads do not merge records. Tables are limited to 50,000 rows, 200 columns and 250,000 cells, with 200,000 characters per field and 200 per field name. Each output is limited to 20 MB, with a 64 MB accumulated result budget and a 20-second worker deadline. Cancellation terminates the processor; failed files can be corrected or retried.
Your session stays local
Files, pasted text, previews, parsing and ZIP creation stay on your device. No data is stored in a history or sent to analytics. Clear the tool, leave it or refresh to release the session. Read how local processing works. For pictures and documents, use the image tool directory.