SmartQueryTools

CSV Tools

80 free CSV tools. All run in your browser, with no uploads and no account.

Convert CSV to another format

Convert other formats to CSV

View, inspect and query CSV files

Clean & fix: CSV

Remove duplicates

Remove duplicate rows from CSV files instantly in your browser. No upload, no server — 100% private.

Fuzzy deduplicate

Find near-duplicate rows in CSV files using Levenshtein edit distance or Jaro-Winkler similarity — all in your browser. Set your own threshold and download the matched pairs as CSV — no upload required.

Trim

Trim leading and trailing whitespace from all text columns in CSV files, directly in your browser. No upload required.

Fill empty values

Fill empty and null values in CSV files with a custom replacement value, directly in your browser.

Coalesce columns

Fill null values in CSV files from other columns — return the first non-null value across up to 8 columns in priority order. Add the result as a new column. Runs entirely in your browser.

Find & replace

Find and replace text values in CSV files directly in your browser. Supports plain text and regex patterns across any column — no upload required.

Convert case

Convert text columns to UPPERCASE, lowercase, or Title Case in CSV files directly in your browser. Apply case conversion to any or all text columns at once — no upload required.

Change column types

Change column data types in CSV files directly in your browser. Cast text to numbers, dates to timestamps, or any supported type conversion — no upload required.

Repair file

Repair malformed CSV files directly in your browser. Fix unbalanced quotes, inconsistent column counts, BOM markers, and mixed line endings — no upload required.

Convert encoding

Detect and convert the character encoding of CSV files directly in your browser. Switch between UTF-8, Latin-1, Windows-1252, and more — no upload required.

Validate emails

Validate email addresses in CSV files directly in your browser. Add a boolean column flagging valid and invalid emails, or filter to show only invalid rows — no upload required.

Validate structure

Validate CSV file structure in your browser. Check null counts, distinct values, and data types for every column — no upload required.

Filter & select: CSV

Reshape & combine: CSV

Sort

Sort CSV files by any column, ascending or descending, directly in your browser.

Split

Split CSV files into multiple smaller files by row count, directly in your browser.

Merge

Merge and concatenate multiple CSV files into one, directly in your browser.

Rename

Rename columns in CSV files instantly in your browser. No upload, no server — your data stays on your device.

Transpose

Transpose CSV files — flip rows and columns — directly in your browser. No upload, no server.

Unpivot

Reshape CSV files from wide to long format directly in your browser. Melt multiple columns into variable/value pairs — no upload required.

Change delimiter

Change the delimiter in CSV files — switch from comma to pipe, semicolon, tab, or any custom character — in your browser.

Split column

Split a column into multiple columns by delimiter in CSV files directly in your browser. Turn "First Last" into separate first and last name columns — no upload required.

Combine columns

Combine multiple columns into one in CSV files directly in your browser. Merge first name and last name, join address fields, or concatenate any columns with a custom separator — no upload required.

Group concatenate

Concatenate text values within each group in CSV files directly in your browser. Group rows by a column and join the values of another column into a single delimited string — no upload required.

Compare

Compare two CSV files directly in your browser. See rows only in file A, only in file B, and rows common to both — no upload required.

Compare schemas

Compare the schemas of two CSV files directly in your browser. See which columns exist in each file and spot type mismatches — no upload required.

Add & calculate columns: CSV

Calculated column

Add a new column to CSV files computed from an arithmetic expression over existing columns. No formulas, no code — just point and click.

Conditional column

Add a new column to CSV files based on an if/else condition directly in your browser. Set a value for rows that match and a different value for rows that don't — no upload required.

Add row numbers

Add a row number index column to CSV files directly in your browser. Set the column name and starting number — no upload required.

Add UUID column

Add a UUID column to CSV files directly in your browser. Generate random UUIDv4 or time-ordered UUIDv7 identifiers for every row. Choose the column name and position — no upload required.

Hash columns

Anonymise or pseudonymise columns in CSV files by replacing values with MD5, SHA-256, or DuckDB hashes — directly in your browser. Useful for GDPR compliance and sharing data without exposing PII — no upload required.

Round numbers

Round numeric columns in CSV files to any number of decimal places directly in your browser. Set precision per column with a simple slider — no upload required.

Pad column

Left-pad or right-pad a column in CSV files to a fixed width directly in your browser. Zero-pad numeric codes, pad product IDs to a fixed length, or right-pad text fields — no upload required.

Bin column

Bucket a numeric column in CSV files into labelled ranges — equal-width bins or custom edges. Runs entirely in your browser.

Regex extract

Extract text matching a regular expression from CSV files directly in your browser. Pull out emails, URLs, phone numbers, or any pattern into a new column — no upload required.

Extract JSON column

Extract values from a JSON-encoded column in CSV files into a new flat column using a JSON path expression. Runs in your browser.

Parse URLs

Parse URL columns in CSV files and extract host, path, query string, and fragment into separate columns — directly in your browser, no upload required.

Dates & times: CSV

Analyse: CSV

Aggregate

Group and aggregate CSV files by any column directly in your browser. Calculate sum, average, min, max, and count for any numeric column — no upload required.

Count by value

Group and count rows by any column in CSV files directly in your browser. Sort by frequency or value to find the most common entries — no upload required.

Percent of total

Add a percentage-of-total column to CSV files directly in your browser. Show each row's share of the grand total, or the share within each group — no upload required.

Percentile

Compute percentiles, median, MAD, mode, and kurtosis for numeric columns in CSV files directly in your browser. Optionally group by a category column. Results download as CSV — no upload required.

Arg max / min

Find the value of one column at the row where another column is maximum or minimum in CSV files — directly in your browser. Optionally group by a category to get per-group results. No upload required.

Rank

Add a rank column to CSV files based on any column's values. Choose RANK, DENSE RANK, or ROW NUMBER, with optional partitioning — runs entirely in your browser.

Running total

Add a running total column to CSV files for any numeric column. Optionally order by a date or sequence column and restart totals per group — no upload required.

Moving average

Add a moving average, rolling sum, rolling min, or rolling max column to CSV files directly in your browser. Choose window size, order-by column, and optional partitioning — no upload required.

Lag / lead

Add a LAG or LEAD column to CSV files to shift any column forward or backward by N rows. See previous day's sales, next value in a sequence, or any time-shifted comparison — runs entirely in your browser.

Normalize

Normalize numeric columns in CSV files using min-max scaling (0–1) or z-score standardisation (mean=0, std=1). Adds new columns alongside the originals — no upload required.

Detect outliers

Detect statistical outliers in CSV files directly in your browser. Flag or remove rows where numeric values exceed a chosen number of standard deviations from the mean — no upload required.

Correlation matrix

Compute a Pearson correlation matrix for numeric columns in CSV files directly in your browser. Instantly spot which variables move together — colour-coded heatmap, no upload required.

CSV Format Comparisons

About CSV

CSV (Comma-Separated Values) is the universal format for tabular data. Every spreadsheet application, relational database, programming language, and data tool can read and write CSV files, making it the default choice for data exchange across industries. A CSV file is plain text — each line is a row, columns are separated by commas (or another delimiter), and the first line is usually column headers.

Data analysts, developers, finance teams, and operations staff all work with CSV daily. It is the default export format from CRMs, e-commerce platforms, accounting software, analytics dashboards, and relational databases. If you have ever downloaded a report from Salesforce, Shopify, QuickBooks, or Google Analytics, you have a CSV file.

Despite its universality, CSV has real limitations. It stores everything as plain text with no embedded type information, so numbers and dates are indistinguishable from strings without inference. It handles nested data poorly, compresses inefficiently compared to columnar formats, and can cause parsing issues when values contain commas, quotes, or newlines. Our CSV tools tackle these common frustrations — convert to a better format, clean up whitespace, remove duplicates, split large files, or generate SQL for a database import — all without leaving your browser.

Frequently Asked Questions

What is the difference between CSV and TSV?

Both are plain-text tabular formats. CSV uses a comma as the delimiter; TSV uses a tab character. TSV is preferred when data values frequently contain commas — for example, addresses or free-text descriptions — because it avoids the need for quoting those fields. In all other respects they are identical.

Why does my CSV look wrong when opened in Excel?

Excel auto-detects the encoding and delimiter but can get it wrong. Common causes: the file uses a semicolon delimiter (common in European locales where commas are decimal separators), the file is UTF-8 but Excel interprets it as a legacy encoding, or values contain commas that break column alignment. Use the CSV Viewer here to inspect the file correctly, or re-save it with the correct delimiter using the Change Delimiter tool.

How do I handle a CSV file that is too large for Excel?

Excel has a hard limit of 1,048,576 rows. For larger files, use the Sample or Head tools to extract a manageable subset, the Filter tool to extract only relevant rows, or the SQL Query tool to run aggregations across the full file. SmartQueryTools can handle CSV files with millions of rows entirely in your browser.

What is the best format to convert a large CSV into for analytics?

Parquet. It typically compresses a CSV to 20–30% of its original size using columnar encoding and compression codecs (Snappy or Zstandard). Analytical tools like DuckDB, Athena, BigQuery, Spark, and Pandas can query a specific column in a Parquet file without reading the rest — dramatically faster than scanning a full CSV row by row.