Tool guide / CSV and TSV

Clean spreadsheet data without uploading it

CSV files look simple, but quoted commas, embedded line breaks, duplicate rows, inconsistent columns, and regional delimiters can make quick edits unreliable. Mer Tools processes these files locally in your browser so you can inspect the result before opening it elsewhere.

1. Identify the delimiter

Comma-separated files use ,, TSV files use tabs, and exports from some regions use semicolons. The CSV Cleaner & Deduplicator can detect comma, semicolon, tab, or pipe delimiters. You can also choose one explicitly when a file is ambiguous.

Detection follows the parsed row structure instead of simply counting punctuation, so a comma inside a quoted value is not treated as a separator. One-column files are inherently ambiguous and default to comma.

2. Clean only what you intend to change

The cleaner can trim cell edges, remove empty and duplicate rows, pad short rows, and remove columns that are empty in every row. Every option is visible and reversible before download. Empty-column removal is off by default because an intentionally blank column can still matter to another system.

name ; status ; notes
 Ada ; active ; first visit
 ; ; 
Ada;active;first visit
Linus; pending

name;status;notes
Ada;active;first visit
Linus;pending;

Quoted values and embedded line breaks are retained. The result summary reports how many rows, cells, and columns changed, along with the detected delimiter.

3. Convert between CSV, TSV, and JSON

Use JSON ↔ CSV when an API result needs a spreadsheet or a table needs structured JSON. JSON conversion requires unique, non-empty headers and rejects rows with more cells than the header, preventing silent data loss. Nested JSON values are kept as JSON text inside their cells.

Select Tab (TSV) for data containing many commas, or when another application specifically requests a .tsv file. Changing a delimiter clears the old result so it cannot be downloaded under the wrong format.

4. Inspect and edit the full table

Open the CSV Viewer / Editor to filter rows and edit individual cells. Rows and wide columns are paged for responsiveness, while full exports retain data outside the visible page. Use Download filtered only when you intentionally want a subset.

Saved drafts stay on the device. File imports accept local UTF-8 and BOM-marked UTF-16 text and reject binary input. Current limits are 100,000 rows, 1,000,000 cells, and 10,000,000 characters.

Check the destination

CSV does not define data types, formulas, encodings, or a single universal delimiter. Values such as 001 remain text in Mer Tools, but spreadsheet software may reinterpret them after import. Review its import settings when leading zeros, dates, long numbers, or formula-like text must remain literal.

You can use the same local conversion and cleanup controls in the Mer Tools extension. All tools are free; optional donations support development.