.csv file format
View, inspect, convert, merge, clean, and test CSV files directly in your browser.
Format
.csv
Original files stay unchanged. Tools download a new file when output is generated.
Every tool listed here works with .csv files and runs in your browser. If the task you need is not here, the related formats below may cover it.
Open, preview, search, and inspect CSV files in your browser.
Convert CSV table data into JSON arrays and objects.
Convert JSON arrays and objects into CSV table data.
Merge CSV files by keeping the first header and appending rows from later files.
Generate messy CSV data for import, parser, and validation testing.
Add controlled noise, missing values, and bad rows to datasets for testing.
RFC 4180 describes common practice rather than defining a standard everyone follows. In real files the delimiter may be a comma, semicolon, or pipe; quoting may be absent, optional, or applied to every field; and embedded newlines inside quoted values are legal but frequently mishandled. Two files with a .csv extension can need different parsing.
This is the most common way CSV data gets corrupted. Opening a CSV in Excel can strip leading zeros from postcodes and IDs, reinterpret text like 2026-01-05 or 1/5 as a date, convert long numeric identifiers to scientific notation, and mangle non-ASCII characters when the encoding is not detected. The file on disk was fine; the import changed it.
CSV carries no encoding declaration, so a reader has to guess. UTF-8 without a byte order mark is the sane default, but some Windows tools expect a BOM and show accented characters incorrectly without one. Line endings vary between platforms too, and a stray lone carriage return inside a quoted field will break naive parsers.
Stacking a folder of same-schema exports is the usual reason to merge CSVs, and the thing to watch is the header row: the first file's header should be kept and repeated headers in later files skipped, or you end up with the word "id" sitting in the middle of your data. Column order must match across files too — merging by position, not by name, is what most tools do.
Excel applies type detection on import. Use Data, then From Text/CSV, and set the problem columns to Text rather than double-clicking the file, or inspect the raw file in a viewer that does no conversion.
Yes, if the field is wrapped in double quotes. A literal double quote inside a quoted field is escaped by doubling it.
The delimiter. TSV uses tabs, which rarely appear in data, so TSV usually needs no quoting at all. CSV is more widely supported but more prone to delimiter collisions.
Not cleanly. Merging appends rows beneath one header, so mismatched columns will misalign. Reconcile the schemas first.