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XLS to CSV Converter
Convert XLS to CSV online for free. Fast, secure, and high-quality conversion with no sign-up or software required.
Maximum file size is 1GB
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How it works
Three steps to your converted file
Everything happens in your browser tab - upload, pick a format, download. The heavy lifting runs on our servers.
Upload your file
Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.
Choose an output format
Pick from over a hundred output formats. Filter by category or search by name - every option is open to everyone, no account needed.
Convert & download
Hit Convert and grab your download link moments later. Originals are erased when the job completes; results are cleared within about an hour.
What is an XLS file?
The XLS format utilizes the Binary Interchange File Format (BIFF) scheme, serving as the default spreadsheet standard for Microsoft Excel from versions 2.0 through 2003. Encapsulated within the Object Linking and Embedding (OLE) Compound File Binary Format (CFBF), XLS files store data in binary streams rather than XML. This proprietary structure supports formulas, Visual Basic for Applications (VBA) macros, and charts but lacks the compression efficiency and corruption resilience of the newer XML-based standards.
How to open an XLS file
Microsoft Excel remains the primary software for full fidelity access to XLS files. On Windows and macOS, the operating system associates these files with the Office suite if installed. Alternatively, open-source solutions like LibreOffice Calc and Gnumeric provide robust reverse-engineered support for reading and editing XLS binaries on Linux and other platforms without requiring Microsoft licenses.
XLS Technical Info
- Full Name
- Excel Binary File Format
- Developed By
- Microsoft
- Initial Release
- 1987
- MIME Type
- application/vnd.ms-excel
What is a CSV file?
A Comma-Separated Values (CSV) file is a delimited text file format codified under RFC 4180 that uses commas to separate values and newlines to separate records. The format stores tabular data (numbers and text) in plain ASCII or Unicode text, where each line constitutes a data record with identical field sequences. It lacks a formalized schema for styling or formulas, relying solely on character separation for data structure, making it a standard for platform-independent data exchange between disparate database management systems (DBMS).
How to open a CSV file
Due to its plain text architecture, CSV files possess universal native support across all major operating systems. They can be viewed and edited using simple text editors like Microsoft Notepad or Vim, but are optimally managed with spreadsheet software such as Microsoft Excel, LibreOffice Calc, or Google Sheets, which parse the delimiters to render the data into columns.
CSV Technical Info
- Full Name
- Comma-Separated Values
- Developed By
- IBM (Fortran origin) / IETF
- Initial Release
- 1972
- MIME Type
- text/csv
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Why RunConvert
The fastest way to convert any file
Purpose-built for speed, privacy, and breadth of format support.
Convert XLS to CSV in seconds
Every XLS to CSV conversion runs on our servers, so your device stays fast and the output quality stays intact.
Fast, cloud-powered
No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.
Secure & private
Encrypted in transit and never shared with anyone. Uploads are erased the moment your job completes, and results shortly after.
Free - no account needed
Convert without creating an account - no credit card, no trial clock. Sign in only if you want history and higher daily limits.
Developer API
Convert XLS to CSV via API
Automate XLS to CSV conversions in three steps: create a job, upload your file, then poll for the result.
# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"tag": "xls-to-csv",
"tasks": {
"upload-file": {
"operation": "import/upload"
},
"convert": {
"operation": "convert",
"input": "upload-file",
"output_format": "csv"
},
"export-result": {
"operation": "export/url",
"input": "convert"
}
}
}'
# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.xls
# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
-H "Authorization: Bearer YOUR_API_KEY"Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.