Convert CSV Files to Excel XLSX via API
Convert CSV files to Microsoft Excel XLSX spreadsheets via REST API. Upload your CSV file as multipart/form-data and receive a formatted Excel workbook in response. Perfect for report generation and data export pipelines.
# Convert CSV file to Excel XLSX
curl -X POST \
https://api.convertfilefast.com/v2/convert/csv-to-xlsx \
-H "Authorization: Bearer YOUR_API_KEY" \
-F "file=@data.csv" \
--output output.xlsx
# HTTP 200 OK — Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheetAdvantages
Why use our API?
Complete and reliable solution for integration in any tech stack.
Excel-Ready Output
Receive a properly formatted XLSX file that opens directly in Microsoft Excel, Google Sheets, and LibreOffice Calc.
Simple Upload
Upload your CSV as multipart/form-data and receive the Excel XLSX binary in response. No configuration needed.
Column Formatting
CSV columns are mapped to Excel cells with automatic column width adjustment and header formatting.
Report Generation
Use in report generation pipelines to deliver data as Excel files to clients, stakeholders, and dashboards.
n8n & Automation
Convert CSV exports from databases or APIs to Excel in n8n workflows and send via email or save to Drive.
Zero Storage
CSV files are converted in memory and deleted immediately. Your data is never stored on our servers.
FAQ
Frequently Asked Questions
How do I convert a CSV file to XLSX format?
Send a POST request to https://api.convertfilefast.com/v2/convert/csv-to-xlsx with your CSV as a multipart/form-data upload using the file field. The API returns a binary XLSX file. See the cURL and Python examples above for ready-to-run code.
Is the output XLSX compatible with Microsoft Excel?
Yes. The output uses the Open XML SpreadsheetML format (ISO 29500), which opens natively in Microsoft Excel 2007 and later, Google Sheets, LibreOffice Calc, and Apple Numbers.
Does the API auto-detect CSV delimiters and encoding?
Yes. The API automatically detects common delimiters including comma, semicolon, tab, and pipe. It also handles UTF-8, ISO-8859-1, and Windows-1252 encodings without any extra configuration.
What are the file size and row limits for CSV to XLSX conversion?
The free plan supports CSV files up to 5 MB. Paid tiers support larger files and higher row counts. See /docs for the full limit table by plan.
Does the conversion preserve data types like dates, numbers, and strings?
Yes. The API applies automatic type coercion: ISO 8601 date strings are stored as Excel date values, numeric values become number cells, and all other values are stored as text. Each cell retains the correct Excel data type.
Can I integrate CSV-to-XLSX conversion in n8n, Zapier, or batch pipelines?
Yes. The API is a standard REST endpoint compatible with any HTTP client. It works out of the box with n8n HTTP Request nodes, Zapier webhooks, Make (Integromat), and Power Automate. See the n8n example tab above for a ready-to-import node configuration.
Start Converting CSV to Excel
Get your API key and convert CSV files to Excel XLSX in seconds. Free plan includes 10 conversions per month.
No credit card. 10 free conversions on Free plan.