Open a large CSV file (even the ones Excel can’t)
Excel stops at 1,048,576 rows — anything past that loads truncated with a “dataset too large” warning, and long before the limit it starts crawling. Google Sheets caps out at 10 million cells, which a wide export burns through in a few hundred thousand rows. This viewer takes a different approach: it indexes the file where it sits on your disk and renders only the rows on screen, so a 200 MB export or a 5-million-row log opens in seconds — with search, filters, sort and column stats that work across every row, not just the visible ones.
Nothing is uploaded anywhere. The file is read in place by your browser, which is also why there’s no size-crawling progress bar to babysit: files up to 256 MB are held in memory, and bigger ones (up to 4 GB) are streamed from disk on demand. Cut your Wi-Fi after the file loads and everything keeps working.
Drop a CSV, TSV or Excel file here
.csv · .tsv · .txt · .csv.gz · .xlsx — files up to 4 GB open here, in your browser. Nothing is uploaded; the file is read in place on your device.
Filters combine with AND. Use the search box for a quick any-column match. Regex filters use JavaScript syntax.
Untick to hide a column (hidden columns are left out of exports). Type to rename — renames apply to exports too.
Exports include your filters, sort, edits and cleanups. Hidden columns are left out; renamed headers apply. The file is generated on your device — nothing is sent anywhere.
How it works
- Drop the file (.csv, .tsv, .txt, .csv.gz or .xlsx). The viewer indexes it and shows the row count immediately.
- Scroll anywhere — millions of rows stay smooth because only the visible window is rendered.
- Search, filter, sort or profile columns; every operation streams through the whole file with a progress bar.
- Export what you need — filtered CSV, Excel, JSON — generated on your device.
Why big CSVs choke spreadsheets (and why this doesn’t)
A spreadsheet loads the entire file into a live grid: every cell becomes an object with formatting, formula hooks and undo history. That’s wonderful at 5,000 rows and hopeless at 5 million. A viewer can cheat honestly — this one scans the file once to record where each row starts (about 4 MB of index per million rows), then materializes only the ~40 rows in your viewport. Filtering and sorting stream through the file in chunks in a background worker, so the page never freezes.
The practical consequence: “too big for Excel” files aren’t actually big data. A 2 GB CSV is a few streaming passes on any laptop — no cluster, no import into a database, no 700 MB desktop app. If you genuinely need joins or aggregation across files that size, that’s the point to reach for a real database; for look at it, check it, filter it, re-export it, a browser is plenty.
The limits, honestly
| Item | Detail |
|---|---|
| Excel | 1,048,576 rows × 16,384 columns — larger files load truncated |
| Google Sheets | 10,000,000 cells per spreadsheet (rows × columns combined) |
| This viewer | Up to 4 GB per file; up to 256 MB held in memory, larger files streamed from disk |
| Excel export from here | Capped at 100,000 rows (use CSV beyond that — Excel can’t open more anyway) |
Excel and Sheets limits checked against Microsoft and Google documentation, July 2026 — confirm against their current docs if it matters for your workflow.
Good to know
- Opening a file a second time is instant if you leave the tab open — the index is kept until you load another file.
- On a 4 GB laptop, prefer the streaming path: close other tabs before opening files near the 256 MB in-memory threshold.
- If the columns come out wrong, it’s almost always the delimiter — override it in the toolbar (semicolon exports from European systems are the usual culprit).
Frequently asked questions
How big a CSV can this actually open?
Up to 4 GB per file. Files up to 256 MB are read fully into memory for the fastest experience; larger files stay on disk and rows are read on demand as you scroll or run operations. Row count matters less than bytes — 10 million short rows are easier than 2 million very wide ones.
Is the whole file really not uploaded?
Really. The site is static — there is no server that could receive your file. Parsing happens in a web worker in your browser, reading the file from your own disk. You can verify it: open DevTools → Network while loading a file (no upload requests), or switch off Wi-Fi after the page loads — everything keeps working.
Why does Excel say my file is too large?
Excel’s grid physically ends at 1,048,576 rows and 16,384 columns. When a CSV has more, Excel loads what fits and warns that some data wasn’t loaded — dangerous, because a truncated file looks complete. If you only need to inspect, filter or split the file, open it here instead; if you need Excel-style analysis on the full data, Excel’s own Power Query (Data → From Text/CSV) can aggregate past the grid limit.
What about opening large files in Google Sheets?
Sheets enforces 10 million cells per spreadsheet — at 20 columns that’s 500,000 rows, and imports that exceed it simply fail. It also gets sluggish well before the cap. For files in that zone, a local viewer avoids both the upload wait and the cell budget.
Can I edit the file, not just view it?
Yes — double-click any cell to edit it, remove duplicates, trim whitespace, find & replace, hide or rename columns, then export. Your original file on disk is never touched; changes only exist in the exported copy.