A spreadsheet view for messy data files
CSV is everywhere — exports, reports, data dumps — but opening one in a text editor is painful and firing up Excel is overkill (and risks the auto-mangling Excel is infamous for). This tool parses your file into an editable grid in the browser: view it as a table, fix values in place, filter, and export clean CSV back out. Nothing uploads; the file is parsed and edited entirely in your device’s memory.
Why it stays fast on huge files
Naively rendering a 100,000-row CSV would stamp 100,000 table rows into the DOM and lock up the tab. This editor uses DOM virtualization — it only renders the ~30–50 rows actually visible in the viewport, recycling them as you scroll. The full dataset lives in a JavaScript array in memory; the DOM only ever holds what you can see. That’s how it handles multi-megabyte files smoothly, with the practical ceiling set by your device’s available RAM rather than a row count.
The quoting rules that keep columns aligned
Almost every “my columns are misaligned” problem traces back to one cause: a value that contains the delimiter wasn’t quoted. The RFC 4180 rules the parser follows:
| Situation | Correct CSV |
|---|---|
| Value has a comma | "Smith, John" |
| Value has a quote | "He said ""hi""" |
| Value spans lines | "line one⏎line two" (quoted) |
If an import looks scrambled, the source CSV likely has an unquoted delimiter inside a field — fixing the quoting in the source (or re-exporting from the origin tool) resolves it.
The encoding gotcha
If accented or non-Latin characters arrive garbled, the file was probably exported in a legacy encoding (Windows-1252, ISO-8859-1) while the parser reads UTF-8. Re-export or convert the file to UTF-8 before loading it, and international text renders correctly. Once your data is clean here, you can hand it to the JSON to CSV converter or the CSV to SQL generator for the next step.