RunConvert

OTS to XLSX Converter

Convert OTS to XLSX online for free. Fast, secure, and high-quality conversion with no sign-up or software required.

Free to useNo file stored beyond 1 hourEncrypted over TLS 1.2/1.3No watermarks

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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.

01

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.

02

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.

03

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 OTS file?

The OpenDocument Spreadsheet Template (OTS) is a file format defined by the OASIS OpenDocument standard (ISO/IEC 26300) specifically for creating reusable spreadsheet blueprints. Structurally identical to the ODS format, it uses ZIP compression to package XML content and styles. The primary technical distinction lies in the file header flags, which instruct the software to open a new, untitled instance of the spreadsheet rather than modifying the original template file, preserving the source data structure and formulas.

How to open an OTS file

OTS files function seamlessly with ODF-compliant software including LibreOffice Calc and Apache OpenOffice across all major operating systems. While Microsoft Excel can open these files, users may need to manually select the file type in the open dialog. Double-clicking an OTS file typically launches a new workbook based on the template rather than opening the template file itself for editing.

OTS Technical Info

Full Name
OpenDocument Spreadsheet Template
Developed By
OASIS
Initial Release
2005
MIME Type
application/vnd.oasis.opendocument.spreadsheet-template

What is an XLSX file?

The XLSX format is the default XML-based spreadsheet file introduced in Microsoft Office 2007, adhering to the Office Open XML (OOXML) standard (ECMA-376 and ISO/IEC 29500). It replaces the binary BIFF structure of legacy XLS files with a ZIP-compressed container holding individual XML files for workbook data, worksheet structure, and metadata. By design, XLSX files strictly exclude Visual Basic for Applications (VBA) macros to prevent malware propagation, distinguishing them from the macro-enabled XLSM format.

How to open an XLSX file

As an industry-standard open format, XLSX is supported natively by Microsoft Excel, Apple Numbers, and Corel Quattro Pro. Cross-platform open-source suites like LibreOffice and Apache OpenOffice provide full read/write capabilities. Cloud-based platforms, including Google Sheets and Microsoft Excel for the Web, allow direct editing in a browser without local software installation.

XLSX Technical Info

Full Name
Excel Open XML Spreadsheet
Developed By
Microsoft
Initial Release
2007
MIME Type
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Why RunConvert

The fastest way to convert any file

Purpose-built for speed, privacy, and breadth of format support.

Convert OTS to XLSX in seconds

Every OTS to XLSX 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 OTS to XLSX via API

Automate OTS to XLSX 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": "ots-to-xlsx",
    "tasks": {
      "upload-file": {
        "operation": "import/upload"
      },
      "convert": {
        "operation": "convert",
        "input": "upload-file",
        "output_format": "xlsx"
      },
      "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.ots

# 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.