XLSX to CSV
Multi-sheet workbooks — pick a sheet, copy or download CSV.
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Using AI? Optimize your prompts first.
Better prompts = better output = fewer revisions.
Try the Prompt Optimizer — Free →You might also like
JSON to CSV Converter
Convert between JSON and CSV instantly. Bidirectional conversion, paste and go. Free, runs in your browser.
PDF to Markdown Converter
Convert PDF files to clean markdown. Save up to 95% on tokens when pasting into ChatGPT, Claude, or Gemini. Free, 100% client-side, no upload.
DOCX to Markdown Converter
Convert Word documents to clean markdown. Save 70-90% on AI tokens. Free, no upload to any server.
AI Prompt Optimizer
Paste any AI prompt and get an optimized version using the ICCSSE framework. Works for ChatGPT, Claude, and Gemini. Free, no signup, runs in your browser.
100% client-side where applicable — your files and inputs stay in your browser. Nothing is uploaded to HundredTabs servers for these tools.