CSV Formatter & Validator

CSV (Comma-Separated Values) is one of the most widely used data exchange formats, supported by every spreadsheet application, database system, and programming language. Despite its simplicity, CSV files frequently contain formatting issues: inconsistent delimiters, missing quotes around fields that contain commas, unescaped special characters, varying line endings, and mismatched column counts between rows. A CSV formatter and validator parses your data, identifies these issues, and produces clean, standards-compliant output. This tool reads your CSV input, detects the delimiter automatically (comma, semicolon, tab, or pipe), parses each row into fields while respecting quoted values, and regenerates the CSV with consistent formatting. It also provides validation warnings for common problems like rows with different column counts, empty rows, and fields with unescaped quotes. All processing happens entirely in your browser using JavaScript — your data, which may contain sensitive business information, customer records, or financial data, is never uploaded to any server.

CSV parsing is more complex than simply splitting on commas because fields can contain commas inside quoted strings. The parser implements a state machine that reads the input character by character, tracking whether it is inside a quoted field. When a quote character is encountered, the parser enters quoted mode where commas and newlines are treated as literal characters rather than delimiters. A double-quote inside a quoted field is interpreted as an escaped literal quote (per RFC 4180). The delimiter detection algorithm examines the first few lines of input, counting occurrences of common delimiters (comma, semicolon, tab, pipe) and selecting the most frequent one. After parsing, the formatter reconstructs the CSV with consistent rules: fields containing the delimiter, quotes, or newlines are automatically quoted, and all quote characters within fields are properly escaped. Column alignment is calculated by finding the maximum width of each column across all rows. The entire process uses native JavaScript string methods and regular expressions, running synchronously in the browser with no external dependencies or network requests.