CSV to Excel
CSV to Excel Converter
Paste or upload CSV and download a real .xlsx — numbers become numbers, columns auto-size. Nothing is uploaded.
- Runs in your browser
- Nothing uploaded
- No sign-up
- Free, no daily limits
- 1Add your file
- 2Choose settings
- 3Download
100% Private: Your CSV is converted entirely in your browser — nothing is uploaded to any server.
Convert CSV to Excel (.xlsx) Online
CSV to Excel is a free browser converter that turns raw CSV records into a native Microsoft Excel workbook (.xlsx) with typed numbers, formula guards, and auto-fitted columns. Paste delimited text or upload files up to 25 MB. The parser runs locally under RFC 4180 rules, auto-detects delimiters across comma, semicolon, tab, or pipe formats, and preserves multi-line text without sending sensitive business figures to remote servers.
Real Conversion Sample: Quoted Fields and Formula Protection
Here is how raw CSV text translates into structured, typed Excel cells. Notice how multi-line addresses stay in one cell, leading zeros remain text, and formula triggers are neutralized:
id,full_name,address,formula_test,amount 101,"Doe, Jane","Apt 4B\n123 Market St",=2+5,1500.50 102,"Smith, John","PO Box 99",@SUM(A1:A5),-42.00 103,"O'Connor, Tim","742 Evergreen",+15550100,0
Row 1: [101] | [Doe, Jane] | [Apt 4B (line 2) 123 Market St]
Formula Cell: '=2+5 (text label, formula disabled)
Amount: 1500.5 (numeric float, SUM capable)
Row 2: [102] | [Smith, John] | [PO Box 99]
Formula Cell: '@SUM(A1:A5) (text label)
Amount: -42 (numeric integer)
Row 3: [103] | [O'Connor, Tim] | [742 Evergreen]
Phone: "+15550100" (preserved string literal)Edge Cases We Handle (And How)
| Input Quirk | What Our Parser Does | Code Location & Rule |
|---|---|---|
| Formula triggers (=, @, +, -) | Defused with a leading apostrophe (') so Excel does not execute macros or DDE commands. Signed numbers stay numeric. | lib/csv.ts:473 (neutralizeFormula) |
| Commas inside quoted fields | RFC 4180 compliant: keeps "Doe, Jane" inside one cell rather than splitting across two columns. | lib/csv.ts:201-217 (parseCsvWithWarnings) |
| Newlines inside quoted cells | Carriage returns (\r\n, \n, bare \r) inside quotes remain in the cell without creating a broken phantom row. | lib/csv.ts:211-215 (endRow guard) |
| Leading UTF-8 BOM (\uFEFF) | Stripped automatically so the first column header name is not corrupted with a zero-width character. | lib/csv.ts:21 (stripBom) |
| Large numeric identifiers | Values with over 15 significant digits remain text strings, preventing IEEE-754 precision rounding on order IDs or card numbers. | lib/csv.ts:286-296 (coerceValue) |
| Sheet name constraints | Truncated to 31 characters max; strips forbidden Excel characters [ ] : * ? / \ and renames reserved "History". | lib/xlsx-convert.ts:181-193 (sanitizeSheetName) |
How to Convert CSV to Excel Step-by-Step
Add CSV Data
Paste your raw records or upload a .csv or .tsv file up to 25 MB.
Configure Types
Keep 'Numbers as numbers' active so numeric fields calculate properly in Excel.
Verify Preview
Review the instant 20-row table preview to verify column boundaries.
Export XLSX
Click Download Excel to generate and save your OpenXML spreadsheet file.
Why Formula Injection Defense Matters
When opening an unvetted CSV in desktop spreadsheet software, cells that begin with formula operators like =, +, -, or @ can trigger remote code execution or data exfiltration through Excel Dynamic Data Exchange (DDE) and HYPERLINK formulas.
Standard RFC 4180 double-quoting does not mitigate this risk because Excel strips the outer quotes before evaluating the formula expression. Our spreadsheet engine neutralizes formula triggers by prefixing a single apostrophe ('). Excel interprets the apostrophe as an instruction to treat the entire cell as literal text, while plain negative and positive numbers (such as -42.50) remain numeric for mathematical calculations.
Core Capabilities of TryDocsy's CSV to Excel Tool
Client-Side Privacy
Workbooks compile in browser memory. Customer data never touches external servers.
Lossless Numeric Typing
Decimal values convert to real IEEE-754 numbers; leading-zero codes stay strings.
Automated Column Widths
Calculates character widths with padding so tables open without cramped columns.
Live Sync Preview
Inspect the first 20 rows immediately while large datasets parse in the background.
Multi-Delimiter Sniffing
Auto-detects comma, semicolon, tab, and pipe separators without manual re-formatting.
No Registration or Limits
Convert unlimited files up to 25 MB each without accounts, subscriptions, or watermarks.
When Not to Use This Web Tool
This in-browser converter enforces a strict 25 MB input cap (26,214,400 bytes) to prevent browser tab crashes. If you need to convert multi-gigabyte database dumps or continuous server log files, use high-performance CLI utilities like in2csv file.csv > file.xlsx from the csvkit suite or stream records directly into DuckDB.
Frequently Asked Questions
How do I convert CSV to Excel without Excel installed?
Paste your CSV text or drop a .csv file into the input box above. The tool parses your records locally and generates an OpenXML (.xlsx) workbook directly in your browser. Click Download Excel to save a real spreadsheet that opens cleanly in Microsoft Excel, Google Sheets, LibreOffice Calc, or Apple Numbers.
Why does Excel show my CSV in one column?
Excel determines delimiters using your operating system regional settings. In many European locales, Excel expects semicolons instead of commas, grouping comma-separated fields into column A. Our converter lets you select or auto-detect comma, semicolon, tab, or pipe separators and writes a true multi-column .xlsx binary where column boundaries are fixed.
How does formula injection defense protect my spreadsheet?
Spreadsheet software evaluates cells beginning with equals (=), plus (+), minus (-), or at (@) as executable formulas or Dynamic Data Exchange (DDE) commands. Untrusted CSVs from web forms or CRM exports can exploit this. Our converter prepends a single quote prefix (') to formula triggers so desktop spreadsheet apps display them as literal text instead of running commands.
What happens to leading zeros in postal codes or phone numbers?
Standard spreadsheet imports often misinterpret zero-padded codes like 007 or 01234 as decimal numbers and strip the leading zeros. Our parser tests numeric literals against canonical decimal patterns. Values with leading zeros or telephone formatting are preserved as text strings, protecting postal codes and identifiers from data corruption.
Does it handle quoted fields with commas and line breaks?
Yes. The parser implements RFC 4180 specifications. Cells wrapped in double quotes can safely hold embedded commas, newline characters, and escaped quotes (""). The parser keeps multi-line text blocks within their original row instead of splitting your table across phantom records.
What is the maximum file size for in-browser conversion?
This converter processes files up to 25 MB (26,214,400 bytes) in client memory. Parsing and workbook compilation run in your browser tab without network transfer. For massive database exports exceeding 50 MB, command-line tools like in2csv or DuckDB offer faster streaming performance.