CSV, Done Right
CSV looks trivial, a value, a comma, a value, until a field contains a comma, Excel eats your leading zeros, or every umlaut turns to mojibake. These guides cover the quoting rules that actually govern the format, comma versus semicolon delimiters, the silent conversions Excel applies and how to stop them, getting UTF-8 right, querying a CSV with real SQL, and pivot tables from first principles. Each links a tool that runs entirely in your browser, so your data never leaves the page.
CSV Quoting Rules: Why Splitting on Commas Breaks Your Data
What RFC 4180 actually requires: when a CSV field must be quoted, how to escape a double quote, and why naive split-on-comma parsers corrupt rows.
Comma, Semicolon, or Tab: Why Excel Writes CSV Files That Other Tools Reject
Why Excel exports semicolon CSVs in half of Europe, how the decimal comma causes it, and how to convert or import any delimiter cleanly.
Stop Excel Silently Changing Your CSV Data (Zeros, Dates, Big Numbers)
Excel quietly rewrites CSV data on open: dropped leading zeros, gene names turned into dates, IDs in scientific notation. Why it happens and how to stop it.
ü Instead of ü: Fixing Broken Special Characters in CSV Files
Why ü, é, and € turn into ü, é, and € when Excel opens a CSV, what the UTF-8 byte order mark does, and how to save and repair files correctly.
Query a CSV with SQL, No Database Setup Required
Load a CSV as a SQL table in your browser and answer real questions with WHERE, ORDER BY, GROUP BY, and HAVING. A worked mini-tutorial on one dataset.
What Is a Pivot Table? Rows, Columns, Values, and Aggregation Explained
A pivot table turns a flat list of records into a cross-tab summary. Learn rows, columns, values, and aggregations with a worked CSV example.
Tools in this guide
CSV Editor
Edit CSV in a spreadsheet-style grid in your browser: add or remove rows and columns, rename headers, then export clean CSV. Nothing is uploaded.
Change delimiter
Change a file's delimiter: read CSV with one separator and write it with another, such as comma to tab (TSV) or pipe. Runs in your browser.
CSV / Excel
Convert CSV to an Excel .xlsx file and Excel back to CSV, entirely in your browser. Works in both directions.
Query CSV (SQL)
Run SQL SELECT queries against a CSV in your browser: it loads into a table you can filter, group and join. Nothing is uploaded.
Pivot CSV
Build a pivot table from CSV in your browser: group by a field, spread another across columns and aggregate. Nothing is uploaded.
CSV escape
Escape values so they are safe CSV fields: quotes are doubled and fields with commas or line breaks are quoted. Runs in your browser.