CSV to JSON Converter: Convert CSV to JSON Online | Free Tool

A Yes, missing values become null in the JSON output. For example, a row with 'name,age,city' and 'Alice,,NYC' turns into {"name":"Alice","age":null,"city":"NYC"}. Empty strings in quoted fields like "" stay as empty strings, not null. This matches standard JSON behavior for APIs. Check your data for unintended blanks before converting.

A Yes, the converter fully supports UTF-8 encoding. Paste CSV data with Japanese, Chinese, or accented characters and they'll appear correctly in JSON output. For example, a header like '名前' converts to that exact Japanese key. Test it with a row containing 'café' — the é stays intact. If you copy from Excel on Windows, watch out for BOM characters; trim your data if you see unexpected symbols.

A Our converter does that automatically. The JSON appears in a readable, indented format with proper line breaks after each object. Copy the output and paste it into any editor — you'll see clean structure, not a wall of text. If you're feeding this into an API or script, we also expose a compact mode toggle at the bottom of the output panel. Toggle it on for minified JSON, off for pretty-printed. Handy for QA testers who need to compare payloads visually.

A JSON keys with spaces are technically valid but most APIs and databases reject them. Our converter strips spaces and lowercases the first letter automatically. A header like "User Name" becomes "userName". Different separator? "First Name" turns into "first_name" if you're using snake_case mode. Toggle this in the options panel above the output. QA testers love this for matching API contract specs. Paste your CSV first, then pick your key format — no regenerating needed.

A Our converter keeps duplicates intact rather than merging them. If you have two columns called "price", you'll get two "price" keys in each JSON object. That's valid JSON but tricky to handle downstream. We recommend renaming one to "price_2" before pasting. This matters for QA testers validating API payloads where duplicate keys cause silent data loss. The JSON spec technically allows duplicates, but most parsers keep only the last one.

A No hard limit exists, but browser memory caps practical size around 10,000 rows or 5 MB. Pastes larger than that can freeze your tab on older machines. For hefty files, split them into chunks and convert each batch separately. Backend devs often batch-convert 2,000-row slices when building mock API responses. If you hit slowness, your CSV likely has complex quoting or multiline fields — strip those first. The converter itself won't corrupt data, but a crashing browser tab does lose your work.

A We trim leading and trailing whitespace from each value automatically. Internal spaces stay as-is, so "first name" maintains its gap. Tabs get converted to single spaces, preventing them from breaking your JSON structure. One edge case: quoted fields like " NY " become "NY" after trimming. That's standard behavior you'll expect from most parsers. If your data intentionally contains leading zeros or spaces, wrap those values in quotes. This tool follows RFC 4180 closely.

A Yes, it infers types from your values. A cell containing 42 becomes the number 42, not "42". Values like true and false convert to JSON booleans. But phone numbers with leading zeros stay strings, which is what you want. One gotcha: a ZIP code like 01234 stays a string for that exact reason. If you need everything as strings, wrap your values in quotes before pasting.

A Your browser handles all conversions locally via client-side JavaScript. No data ever leaves your computer or gets saved on any external server. DevOps engineers handling sensitive configuration files rely on this security guarantee daily. Paste your data with confidence because privacy is baked right into the architecture. Clear your cache and your session vanishes completely.

A Yes, the tool parses multi-line cells correctly if they are enclosed in double quotes. A description field spanning two lines inside quotes stays intact inside the resulting JSON string value. But unquoted line breaks will break the row parsing entirely. Paste a 3-row sample with quoted breaks to test it. Always verify your source CSV uses proper quoting before running large batches.