# CSV Malformed Row Surgeon

Surgically repair malformed CSV rows one at a time: unescaped (stray) quotes, mixed delimiters (tab/semicolon/comma in the same file), BOM-prefixed headers, CRLF/CR line endings and trailing empty lines. The surgeon parses tolerantly, shows a row-level red/green diff of every change it made (before → after, with the repair reason tagged), lists the rows it accepted unchanged, and emits the cleaned CSV. Optional AI repair can review suspicious rows after the deterministic pass. It complements the CSV Validator (which only reports problems) by actually fixing the damaged rows.

> Canonical page: https://elysiatools.com/en/tools/csv-malformed-row-surgeon

- **Category:** Development

- **Keywords:** csv, malformed, repair, fix, surgeon, stray quote, mixed delimiter, bom, line ending, crlf, escape, quoting, row, etl, data cleaning

## Overview

A row-level CSV repair tool for data engineers and ETL developers:

1. Paste CSV data. Pick the input delimiter and the delimiter you want in the output (they can differ — useful for normalising a tab file to comma CSV).
2. Toggle the repairs to apply: strip a leading UTF-8 BOM, escape stray (unescaped) quotes, quote any field that contains the delimiter or a newline, normalise CRLF/CR line endings to LF, drop empty lines, trim cell whitespace, and detect/rewrite mixed delimiters.
3. The surgeon parses tolerantly — it does not stop at the first broken row the way a strict parser would. It keeps going so every damaged row appears in the report.
4. A row-level red/green diff shows each changed row before → after, tagged with the repair reason (e.g. "Delimiter ',' → '\t'", "Escaped stray quote(s)", "Normalized line ending"). This is the accept/reject audit trail: you can see exactly what was changed and decide whether to trust it.
5. Rows that needed no repair are listed separately as "accepted unchanged", and the cleaned CSV is emitted at the bottom (toggle the output off to skip it for large files).
6. Enable AI repair if you want suspicious rows to receive a second pass. The AI only rewrites rows flagged as suspicious and falls back to the deterministic result if the returned field shape looks unsafe.

Offline and deterministic: pure string processing, no external parser dependency.

## Inputs

- **CSV data** (textarea): id,name,note 1,Ada,"loves, commas" 2,Grace" Hopper,unescaped quote
- **Input delimiter** (select)
- **Target delimiter** (select)
- **Strip UTF-8 BOM** (checkbox)
- **Unescape stray quotes** (checkbox)
- **Quote fields with delimiter/newline** (checkbox)
- **Normalize line endings (CRLF/CR → LF)** (checkbox)
- **Drop empty lines** (checkbox)
- **Trim cell whitespace** (checkbox)
- **Detect and rewrite mixed delimiters** (checkbox)
- **Use AI repair for suspicious rows** (checkbox)
- **Output repaired CSV** (checkbox)

## When to use

- When an ETL pipeline or database import fails due to a single malformed row with unescaped quotes or mixed delimiters.
- When you need to normalize inconsistent CSV files generated by different operating systems or legacy export tools.
- When you want to audit and repair CSV formatting errors with a clear before-and-after diff before importing data into production.

## How it works

- Paste your raw CSV data into the input area and select your input and target delimiters.
- Configure the deterministic repair rules, such as stripping UTF-8 BOM, escaping stray quotes, trimming cell whitespace, or enabling optional AI-assisted repair for suspicious rows.
- Review the row-level red/green diff report showing exactly what was changed and why, alongside the list of unchanged accepted rows.
- Copy or download the fully repaired and standardized CSV output.

## Use cases

- Fixing legacy database exports that contain unescaped quotes inside text fields.
- Stripping UTF-8 BOM headers and converting Windows CRLF line endings to standard LF for Linux-based ETL systems.
- Standardizing mixed-delimiter files where some rows use commas and others use tabs or semicolons.

## Frequently asked questions

### How does this tool handle files with mixed delimiters?

It detects alternative delimiters like tabs or semicolons within the same file and rewrites them to match your target delimiter.

### What is the difference between this tool and a standard CSV validator?

A validator only reports formatting errors, whereas this surgeon actively repairs the malformed rows and outputs a clean file.

### How does the optional AI repair feature work?

It reviews rows flagged as suspicious after the deterministic pass and attempts to rewrite them, falling back to the rule-based result if the structure is unsafe.

### Can I convert a tab-separated file to a comma-separated file?

Yes, by setting the input delimiter to Tab and the target delimiter to Comma, the tool will normalize the delimiters during the repair process.

### Is my data sent to a server during the deterministic repair?

No, the deterministic repair rules run entirely offline in your browser using pure string processing.

## Related tools

- [CSV Header Alias Resolver](https://elysiatools.com/en/tools/csv-header-alias-resolver): Map messy CSV headers onto a clean target schema. Paste a CSV whose first row holds inconsistent column names (Customer ID, user_id, customerId, CUST_ID…) plus your target schema (one column per line) and an optional "alias=target" dictionary. Each source header is resolved through four layered passes — exact, dictionary, normalized (strips case/accents/separators/camelCase), then fuzzy edit-distance — and shown in a mapping table with method and confidence, plus target coverage and an optional normalized CSV export.
- [Data Boundary Processor](https://elysiatools.com/en/tools/data-boundary-processor): Advanced boundary value processing tool that identifies and handles minimum/maximum values in numerical data. Perfect for data validation, range checking, statistical analysis, and data preprocessing. Features: - Multiple boundary detection methods (absolute, percentile, standard deviation) - Flexible handling strategies (clip, remove, replace, transform) - Custom range validation - Asymmetric boundary handling - Batch processing capabilities - Comprehensive boundary statistics - Data quality assessment - Visual boundary reports Common Use Cases: - Data validation and quality control - Sensor data range checking - Financial data limit enforcement - Statistical data preprocessing - Machine learning feature engineering - Database constraint validation
- [AI Data Normalizer](https://elysiatools.com/en/tools/ai-data-normalizer): AI-powered data format normalization tool that intelligently cleans and standardizes messy data using advanced AI analysis
- [Correlation Analyzer](https://elysiatools.com/en/tools/correlation-analyzer): Advanced correlation analysis tool that calculates correlation coefficients between variables to measure the strength and direction of their linear relationships. Perfect for statistical analysis, financial modeling, scientific research, and data exploration. Features: - Multiple correlation methods (Pearson, Spearman, Kendall) - Correlation matrix generation - Statistical significance testing (p-values) - Confidence intervals calculation - Heatmap visualization - Scatter plot matrix generation - Missing value handling strategies - Outlier detection and handling - Group analysis capabilities - Detailed statistical reports Common Use Cases: - Financial market analysis and risk assessment - Scientific research and hypothesis testing - Customer behavior and marketing analysis - Healthcare and medical data analysis - Quality control and process optimization - Educational performance evaluation
- [CSV Deduplicate Rows](https://elysiatools.com/en/tools/csv-deduplicate-rows): Upload a CSV file or paste CSV text, remove duplicate rows using exact or fuzzy matching, and download a cleaned CSV.
- [CSV Validator](https://elysiatools.com/en/tools/csv-validator): Validate CSV structure, detect malformed rows, unbalanced quotes and column mismatches
- [BOM Character Remover](https://elysiatools.com/en/tools/data-bom-remover): Remove BOM (Byte Order Mark) characters from text and file content. Perfect for cleaning up text files that have encoding issues, fixing CSV imports, and preparing data for processing. Features: - Detect and remove UTF-8 BOM (EF BB BF) - Detect and remove UTF-16 BOM (FE FF or FF FE) - Detect and remove UTF-32 BOM (00 00 FE FF or FF FE 00 00) - Support multiple input formats - Visual BOM character display - Detailed detection report - Support for batch text processing Common Use Cases: - Fix CSV file import errors - Clean up text file encoding issues - Prepare data for JSON parsing - Fix XML parsing problems - Resolve API data encoding conflicts - Standardize text data format
- [Data Cleaner](https://elysiatools.com/en/tools/data-cleaner): Clean and standardize data by fixing spelling errors, standardizing formats, removing duplicates, and filling missing values

## Samples

- [CSV Samples](https://elysiatools.com/en/samples/csv-samples): Sample CSV files with various data types, sizes, and complexity levels
- [Python Samples](https://elysiatools.com/en/samples/python): Essential Python code examples and Hello World demonstrations
- [Windows String Processing - C# Samples](https://elysiatools.com/en/samples/windows-string-processing-csharp): Comprehensive C# string processing examples for Windows platform including string manipulation, splitting, joining, regex operations, and text analysis
- [WebRTC Real-Time Communication Samples](https://elysiatools.com/en/samples/webrtc-samples): Comprehensive WebRTC samples for peer-to-peer audio/video communication, data channels, screen sharing, and signaling server implementation

## Related content

- [Semi-Structured Text Parsing and Table Extraction Tools](https://elysiatools.com/en/hubs/semi-structured-text-table-extraction): Turn fixed-width text, mixed-delimiter records, logs, and HTML or Markdown tables into clean CSV, JSON, XML, or Excel outputs with focused parsing and repair tools.
- [CSV Export and Table Conversion Tools](https://elysiatools.com/en/hubs/csv-convert): Compare CSV to Excel, JSON, HTML, Markdown, XML, and text conversion tools in one hub for tabular export and interchange workflows.
- [CSV Cleanup and Table Reshaping Tools](https://elysiatools.com/en/hubs/csv-utility): Compare CSV cleanup, filtering, sorting, grouping, merging, splitting, and table reshaping tools in one hub for spreadsheet and import/export workflows.
- [Barcode, QR Code, and Label Tools](https://elysiatools.com/en/hubs/barcode-utility): Compare barcode generation, QR code creation and decoding, UPC/EAN validation, WiFi QR sharing, and printable label tools in one hub.