CSV Viewer & Reader
Fast CSV Viewer is a free online CSV viewer built for large files. Drop in a .csv,
.tsv or delimited file and it is parsed, laid out as a table and ready to sort and
filter instantly — directly in your browser.
Your file never leaves your computer. There is no upload and no server-side parsing, so even huge, sensitive CSV files stay completely private. A streaming WebAssembly RFC 4180 parser and virtual scrolling keep things fast on big and multi-gigabyte CSV files — tested with 20GB files.
What you can do
- Open large CSV files — view huge and big CSV files that crash spreadsheets and editors.
- Sort columns — click a header to sort ascending, descending or off, numeric-aware.
- Filter rows — keep rows matching a substring or regex, per column or across all columns.
- Resize & auto-fit columns — drag a column edge, or fit every column to its widest cell instantly.
- Auto-detect the delimiter — comma, semicolon and tab (TSV), or force one from the toolbar.
- Handle real-world CSV — quoted fields, doubled quotes, embedded newlines, CRLF/LF and BOM.
- View CSV online for free — no install, no signup, works in any modern browser.
Frequently asked questions
How do I open a large CSV file?
Drag and drop your .csv file onto this page, or click Open CSV to browse for it. Fast CSV Viewer streams the file inside your browser and paints the first rows before parsing finishes, so even large CSV files open quickly.
What is the largest CSV file I can open?
There is no fixed limit. The viewer streams CSV in small blocks across multiple web workers and uses virtual scrolling, so it has been tested with 20GB files. Practical limits depend on your device's available memory and browser.
Is my CSV file uploaded to a server?
No. Your file is opened and parsed entirely on your own device. There is no upload and no server-side processing, so private and sensitive CSV files never leave your browser.
Can I sort and filter CSV columns?
Yes. Click any column header to sort it ascending, descending or off (sorting is numeric-aware). Use the filter box to keep only rows that match a substring or a regular expression, scoped to one column or all columns. Both run as a streaming scan over the whole file, locally in your browser.
Does it handle quoted fields, embedded newlines and different delimiters?
Yes. The parser follows RFC 4180: it handles quoted fields, doubled-quote escapes, embedded commas and newlines inside quotes, and CRLF or LF line endings — even when a field is split across the 256 KB streaming block boundary. The delimiter is auto-detected, and you can force comma, semicolon or tab.
Can I view CSV online for free?
Yes. Fast CSV Viewer is completely free, with no signup and no installation. It runs in any modern browser, so you can view CSV online from any computer.
Can I resize or auto-fit columns?
Yes. Drag a column's right edge to resize it, or click Fit columns to size every column to its widest cell. The parser measures the maximum width of each column while streaming, so auto-fit is instant even on huge files, and your column widths are remembered for files with the same header.
Does it support TSV and semicolon-separated files?
Yes. The viewer auto-detects the delimiter and supports comma, semicolon and tab-separated (TSV) files. You can also override the delimiter manually from the toolbar.
How do I create a huge CSV test file?
Use the CSV generator page to stream a CSV file of any size up to 20 GB straight to your disk via the File System Access API. Pick the delimiter, line ending, column count, language and quoting hazards. The data never touches a server and there is no temporary copy in memory — the file is written incrementally as it is generated. Use it to benchmark CSV parsers or to stress-test Fast CSV Viewer on huge inputs.