CSV Viewer & Editor

About CSV Viewer & Editor

CSV Viewer & Editor is a powerful online tool that lets you view, edit, and manipulate CSV (Comma-Separated Values) files directly in your browser. Load CSV files, modify data in a spreadsheet-like interface, add or remove rows and columns, and export to CSV or JSON format—all without uploading sensitive data to a server.

Why are my CSV columns getting split incorrectly?

The almost universal cause is a delimiter mismatch between the file and the parser. CSV is not a single format — it is a family of comma-, semicolon-, tab- and pipe-separated files. RFC 4180 specifies the comma as the canonical separator, but spreadsheets in regions that use a comma as the decimal mark (most of Europe and Latin America) default to a semicolon to avoid ambiguity, and TSV files use a tab. This editor auto-detects the delimiter by sampling the first few lines, but you can override it from the Delimiter dropdown — choose Comma, Semicolon, Tab, Pipe, or a Custom character if the guess is wrong. The second common cause is a field that contains an unescaped delimiter inside a value; wrap such fields in double quotes ("hello, world") and the parser will treat the embedded comma as data.

How do I remove blank rows or duplicate rows from a CSV?

Turn on the Enable editing switch above the table and two cleanup buttons appear in the toolbar. "Remove Blank Rows" deletes every row whose cells are all empty or whitespace-only — the classic trailing-empty-row artifact left behind by spreadsheet exports. "Remove Duplicates" compares each row across all columns, keeps the first occurrence, and drops every later exact match. Both run instantly in memory and report how many rows were removed, and neither touches your original file: download the cleaned data as CSV or JSON when you are done. This makes the tool a quick data-prep step before importing into Excel, a database, or a BI tool.

Is my data uploaded anywhere? Does this work offline?

No upload ever happens. All parsing, editing, blank-row and duplicate removal, and CSV/JSON export run entirely in your browser with JavaScript — the file is read locally and never sent to a server. That makes this a genuinely private, offline CSV editor: customer lists, financial exports, and confidential reports stay on your machine. Once the page has loaded you can even disconnect from the network and keep working, which is also why there are no per-file size limits beyond your device's own memory.

How do I edit cells, headers, rows, and columns?

Enable editing, then type directly into any cell to change its value — the change is stored as soon as you leave the field. Click a column header to rename it. Use the Add Row and Add Column buttons to append new entries, and the × button on a row or header to delete that row or column. If you set a Max rows limit on a large file, only the visible window is editable and the tool warns you; choose All rows to edit the full file. Nothing is written back to your source file until you click Download CSV or Download JSON.

Why are leading zeros in ZIP codes or product IDs being stripped?

This is the most notorious CSV pitfall and it actually happens in the spreadsheet, not in the file. CSV has no concept of data types — every field is just text — so a column containing 01234 is stored faithfully in the file. The problem appears when a spreadsheet such as Excel opens the CSV and auto-detects 01234 as a number, dropping the leading zero. This editor treats every cell as text, so the zero is preserved while you work here, and it never alters numeric-looking strings on export. To survive a round trip through Excel, prefix the value with an apostrophe ('01234) or use the Excel "From Text/CSV" import wizard and explicitly mark the column as Text.

Can I convert a CSV to JSON?

Yes. Click Download JSON and the tool converts your table into an array of objects, using the header row as the keys for each record, and saves a .json file. This is handy for feeding spreadsheet data into web apps, REST APIs, or a NoSQL store. If you have cleaned the data first (removed blank and duplicate rows, fixed headers), the export reflects those edits. To go the other way, download as CSV with your chosen delimiter.

What is the practical difference between CSV, TSV, and NDJSON for tabular data?

CSV (RFC 4180) is the lowest common denominator: every cell is text, the schema is implicit in the header row, and quoting rules handle embedded delimiters. TSV (tab-separated) is a stricter relative used by bioinformatics tools and Hadoop pipelines — tabs almost never appear in data, so no quoting is needed and parsing is trivial, but TSV is less forgiving of dirty input. NDJSON (newline-delimited JSON, one JSON object per line) preserves data types, nested structure, and arrays, which CSV cannot represent at all without ad-hoc encoding. Use CSV when you need to hand a file to a non-technical user with Excel, TSV when you control both ends and want fast parsing, and NDJSON when you have nested or typed data and your pipeline can read JSON streams (Spark, BigQuery, jq, DuckDB all do).