Free CSV Tools — Zero Upload Required
Clean, format, merge, and convert large datasets directly in your browser. Blazing fast WebAssembly processing with complete data privacy.
Built for heavy data lifting
Data Analysts
Excel crashes on 1M+ rows. Writing Python scripts for simple merges takes too long.
✓ Instantly filter, merge, and clean multi-gigabyte datasets directly in the browser via DuckDB.
E-Commerce Managers
Exporting Shopify/WooCommerce products and fixing messy supplier inventory files.
✓ Find & replace text, remove duplicates, and map columns without breaking formatting.
Developers
Need to convert client CSVs to JSON or SQL quickly, but can't risk uploading PII to random cloud tools.
✓ Local JSON/SQL generation with strict privacy. No data ever hits a server.
Clean & Format
Auto-format dates, trim whitespace, and fix broken delimiters.
Find and delete duplicate rows based on specific columns.
Bulk search and replace text across large CSV files.
Instantly delete all blank lines from your dataset.
Convert columns to UPPERCASE, lowercase, or Title Case.
Reshape & Merge
Combine multiple CSV files vertically or horizontally.
Split a massive CSV into smaller files by row count.
Filter rows using complex logic (contains, greater than, etc).
Pull specific columns out to create a new, leaner dataset.
Sort your entire dataset by multiple column headers.
Swap rows and columns (rotate the dataset 90 degrees).
Convert & Export
Convert CSV to XLSX safely without losing leading zeros.
Extract sheets from Excel files into flat CSV files.
Transform tabular data into clean JSON arrays or objects.
Flatten nested JSON data into a structured CSV file.
Generate SQL INSERT statements automatically from CSV data.
Create Markdown tables instantly from your dataset.
Frequently Asked Questions
Can I process large CSV files (1GB+)?
Yes. Refinata utilizes DuckDB WASM to process gigabytes of CSV data directly in your browser's memory without crashing. Since there is no upload, the file size is only limited by your device's available RAM.
Is my customer data safe?
100% safe. Your CSV files never leave your computer. There is no server upload, no database storage, and no network requests made with your data. Refinata is entirely client-side.
Will this mess up my zip codes or leading zeros?
No. Unlike Excel which often auto-formats and destroys leading zeros (e.g., changing '01234' to '1234'), Refinata processes data as strict strings by default, preserving your exact values.
Do I need to install any software?
No installation required. Everything runs natively in your web browser (Chrome, Edge, Firefox, Safari) using modern WebAssembly.