These free online data conversion tools handle the awkward middle steps of moving data between systems, without sending a single byte anywhere. Convert spreadsheet exports, generate typed code from a sample payload, validate identifiers, and check file integrity, all in the browser tab you already have open. No account and no upload.
Paste a spreadsheet export into the TSV to JSON Converter, push a cleaned file through the CSV to SQL Converter, or run a query result back through the SQL to JSON Converter. Hand a sample payload to JSON to TypeScript Interfaces or JSON to Classes and get typed Go, Java or Python straight back. When the shape of the data is the problem rather than the format, the JSON Flattener, JSON Sorter and JSONPath Tester let you probe and reshape it in place.
The same page covers the fiddly file level work that usually sends you hunting. The File Hash Generator and Checksum Verifier handle integrity checks, the Hex Viewer and File Type Identifier tell you what you are actually holding when a file will not open, and the BOM Remover, Line Ending Converter and Text Encoding Converter clear up the mojibake and CRLF problems that break imports. A stray byte order mark at the start of a CSV is a common culprit.
Everything runs in JavaScript that is already loaded in the tab, so there is no upload step and no server round trip. Your production dump in the Data Anonymizer, your customer list in the Email Address Validator, and your payment records in the Credit Card Validator or IBAN Validator all stay in local browser memory. No account, no cookies, no file size cap, and no queue behind other people's jobs.
Only if the tool processes data in your browser rather than on a server. Many popular converters post your file to a backend, where it may be logged, cached or retained under a privacy policy you never read. Every tool on this page runs client side, so the data you paste into the Data Anonymizer, IBAN Validator or JSON Schema Validator stays in the tab's memory and is discarded when you close it. You can verify this by opening your browser's network tab and watching for requests while you convert.
There is no imposed size limit and no signup. Because conversion happens locally, the only real ceiling is the memory your browser will give a single tab, which comfortably covers files far larger than the ten or twenty megabyte caps typical of upload based converters. Nothing is queued behind other users either, so a large TSV to JSON conversion or File Hash Generator run finishes as fast as your own machine can do the work.
Use the check digit rules built into each format, which is exactly what these tools do. The IBAN Validator applies the ISO 7064 MOD 97 test, the Credit Card Validator runs the Luhn algorithm, and the EAN Barcode Check Digit Calculator recomputes the trailing digit. These confirm that a number is well formed and internally consistent, which catches typos and bad test data. They cannot confirm that an account, company or product actually exists, since that requires a live registry lookup.