Frequently Asked Questions

DataClean is a free, client-side data cleaning tool built by Sidequest Labs. It lets you drag-and-drop messy CSV, TSV, or JSON files and instantly clean, dedupe, reformat, and export your data.

Everything runs in your browser — no server uploads, no sign-up required. Once cleaned, you can export your data or send it directly to VizFlow for instant visualization.

Yes. DataClean's core features are completely free and will always be free. This includes:

• Drag-and-drop import for CSV, TSV, and JSON
• Core cleaning: remove blanks, dedupe, trim whitespace, normalize casing
• Column operations: split, merge, rename, reorder, fill blanks, change data types
• Find and Replace (exact match)
• Data quality scoring and column statistics
• CSV export
• Send cleaned data directly to VizFlow

The free tier supports up to 100 rows per dataset. For unlimited rows and advanced features, see Pro plans.

No. DataClean requires no account, no email, and no sign-up. Just open the app, drop your file, and start cleaning.

If you purchase a Pro plan, you will receive a license key via email after checkout. You enter that key directly in the app — no account system involved.

DataClean supports the following input formats:

• CSV (Comma-Separated Values) — the most common tabular format
• TSV (Tab-Separated Values)
• JSON (array of objects)

You can also paste data directly into the app if you have tabular text on your clipboard. The parser auto-detects delimiters.

There are two ways to load data into DataClean:

1. Drag and Drop — Drag a CSV, TSV, or JSON file from your file manager directly onto the upload area.
2. File Picker — Click the upload area or the file input to open your system's file browser and select a file.

The file is parsed entirely in your browser. Nothing is uploaded to any server.

Yes. Below the upload area you will find a text area labeled "Or paste data." You can paste tabular data directly from your clipboard — copied from a spreadsheet, email, or any text source.

DataClean auto-detects the delimiter (comma, tab, semicolon) and column structure. After pasting, click Load to import the data.

Since DataClean runs entirely in your browser, the practical file size limit depends on your device's available memory.

Free tier: Up to 100 rows are displayed and processed. Larger files can be imported but only the first 100 rows are accessible without a Pro license.

Pro: Unlimited rows. Most modern browsers can comfortably handle datasets with tens of thousands of rows. For extremely large files (100,000+ rows), you may notice slower initial parsing depending on your hardware.

DataClean provides a comprehensive set of cleaning operations:

• Remove blank / empty rows — Delete rows where all cells are empty or contain only whitespace.
• Deduplicate rows — Remove exact duplicate rows based on all or selected columns.
• Trim whitespace — Strip leading and trailing spaces from all cells.
• Normalize text casing — Convert text to lowercase, UPPERCASE, Title Case, or Sentence case.
• Standardize date formats — Parse mixed date formats and unify them (e.g., to YYYY-MM-DD).
• Fix number formatting — Normalize thousand separators, decimal points, and currency symbols.
• Find and Replace — Search for text and replace it, with support for exact match (free) and regex with capture groups (Pro).
• Fill blank values — Replace empty cells with a default value, zero, mean, median, or mode.

Pro-only operations include Conditional Transform, Remove Outliers, Pivot / Reshape, Merge with File, and Custom Cleaning Rules.

The Fix All button applies all detected cleaning operations in a single click. When you load data, DataClean scans for issues (blank rows, duplicates, inconsistent casing, extra whitespace, mixed date formats) and displays them.

Clicking Fix All applies every recommended fix at once. Each operation is applied sequentially to the data, and the table updates in real time so you can see the results immediately.

You can always use Undo to revert changes if the result is not what you expected. Each individual fix can also be applied one at a time if you prefer more granular control.

Conditional Transform is a Pro feature that lets you apply if-then logic to your data. You define a condition on a column and a transformation to apply when the condition is met.

For example, you could set up a rule like:

• IF the "Status" column equals "pending" THEN change it to "active"
• IF the "Price" column is greater than 100 THEN add a "High Value" tag
• IF a cell is empty THEN fill it with "N/A"

You can chain multiple conditions and apply different transforms based on complex criteria. This is one of the most powerful Pro-only tools for data transformation.

All column operations are available from the Column section of the toolbar:

• Rename: Click on any column header to rename it directly. You can also use the column menu to enter a new name.
• Split Column: Select a column and choose "Split." Specify a delimiter (e.g., comma, space, dash) and the column will be split into two or more new columns.
• Merge Columns: Select two or more columns and choose "Merge." Specify a separator and the columns will be combined into one new column with values joined by the separator.
• Reorder: Drag and drop column headers to rearrange the order.

All column operations are available on both the free and Pro tiers.

To change a column's data type, open the column menu and select "Change Type." You can convert between:

• Text — Treat all values as strings
• Number — Parse values as numbers (integers or decimals)
• Date — Parse values as dates
• Boolean — Parse values as true/false

When converting to Number or Date, values that cannot be parsed will be flagged. This helps you identify data quality issues early.

The Quality Score is a composite metric from 0 to 100 that evaluates the overall health of your dataset. It is calculated across four dimensions:

• Completeness — How many cells are filled vs. empty across the dataset.
• Consistency — How uniform data formatting is within each column (e.g., consistent date formats, consistent casing).
• Accuracy — How many values match expected types (e.g., numbers in numeric columns, valid dates in date columns).
• Uniqueness — How many rows are unique vs. duplicated.

The score is displayed as a circular gauge with a letter grade (A through F). Each column also receives its own quality badge so you can identify which columns need the most attention. You can click a column's quality badge to see a detailed breakdown of that column's scores across all four dimensions.

Outlier Detection is a Pro feature available on numeric columns. It supports two methods:

• IQR (Interquartile Range) — Values below Q1 minus 1.5x IQR or above Q3 plus 1.5x IQR are flagged as outliers. This is the default and works well for most datasets.
• Z-Score — Values with a Z-score greater than 3 (more than 3 standard deviations from the mean) are flagged. Best for normally distributed data.

When you select a numeric column, the outlier panel shows the detected outliers with their row number, value, and the method used. You can then choose to remove outliers or cap them (replace with the nearest boundary value).

DataClean provides a Statistics Panel that shows per-column statistics for your loaded data. For each column you can see:

• Column name and data type
• Null count — Number and percentage of empty cells
• Unique count — Number of distinct values
• For numeric columns: Min, Max, Mean, Median, Standard Deviation
• For text columns: Most frequent value and its count
• For date columns: Earliest and latest dates

Clicking any column in the statistics table reveals a frequency distribution showing the top values and their counts with visual bar charts. This helps you quickly understand data spread and identify patterns.

DataClean supports multiple export formats:

• CSV — Available on both Free and Pro
• TSV — Pro only
• JSON — Pro only
• Excel (.xlsx) — Pro only

You can also click "Open in VizFlow" to send your cleaned data directly to VizFlow for instant chart visualization — this is available on both Free and Pro.

Excel export (.xlsx) is a Pro feature. Once you have an active Pro license key entered in the app:

1. Clean and prepare your data as needed.
2. Click the Export button in the toolbar.
3. Select "Excel (.xlsx)" from the format dropdown.
4. The file will be generated and downloaded to your device.

The Excel export preserves column headers and data types. The entire export happens client-side — the file is generated in your browser.

Batch Processing is a Pro feature that lets you apply the same cleaning pipeline to multiple files at once.

Here is how it works:

1. Set up your cleaning operations on one file (your "template").
2. Save this as a Pipeline.
3. Select the saved pipeline and upload multiple files.
4. DataClean applies the exact same operations to each file in sequence.
5. Download each cleaned file individually, or download all as a ZIP.

This is especially useful for recurring data imports with the same structure — such as weekly sales reports or monthly sensor data.

No. Your data never leaves your browser.

DataClean is a fully client-side application. Every operation — import, cleaning, transformation, analysis, and export — runs entirely in your web browser using JavaScript. No data is ever uploaded, transmitted, or stored on any server.

This applies to all features, including the free tier and Pro features. Your files stay on your machine at all times.

DataClean is a Progressive Web App (PWA). After your first visit, the browser caches the app's files so it can load without an internet connection.

To enable offline use:

1. Visit dataclean.pages.dev while online.
2. The browser will automatically cache the app files in the background.
3. You can also click the "Install" button in the navigation bar to add DataClean to your home screen or desktop.

Once cached, DataClean works fully offline. All cleaning, analysis, and export operations function without any network connection.

Pro unlocks all features beyond the free tier, including:

• Unlimited rows (free tier is limited to 100 rows)
• Find and Replace with regex and capture groups
• Conditional Transform (if-then logic on columns)
• Custom Cleaning Rules (DSL-based)
• Remove Outliers (IQR and Z-score methods)
• Pivot / Reshape data
• Merge with File (SQL-style joins: inner, left, right, full)
• Batch Processing (apply pipeline to multiple files)
• Save and manage Pipelines with a Template Gallery (11 templates)
• Data Profiling Dashboard
• Share via URL and Embed code
• Custom Themes / Branding (7 palettes + hex color picker)
• Export to TSV, JSON, and Excel (.xlsx)

See the full Free vs. Pro comparison for details.

To upgrade to Pro:

1. Visit the Pro section on the landing page and choose a plan (Lifetime or Yearly).
2. Complete the checkout process via Stripe.
3. You will receive a license key by email.
4. Open the DataClean app and click "Pro" in the header.
5. Enter your license key. It will be validated and stored locally in your browser.

Once activated, all Pro features are immediately available. You do not need to create an account.

All payments are processed securely through Stripe. Accepted payment methods include:

• Visa, Mastercard, American Express, Discover
• Debit cards
• Apple Pay and Google Pay (where available in your browser)

DataClean never sees or stores your payment information. Stripe handles all card details directly.

Yearly plan: Yes, you can cancel at any time. Your Pro access will remain active until the end of your current billing period. You can cancel from your Stripe customer portal, which is linked in your purchase confirmation email.

Lifetime plan: The Lifetime plan is a one-time payment — there is nothing to cancel. You have access to Pro features forever, including all future updates.

In both cases, if you cancel, your license key remains valid until its expiration date. After that, the app gracefully falls back to the free tier.

If your file does not load, try these steps:

1. Check the file format. DataClean supports CSV, TSV, and JSON. Other formats (XLSX, PDF, XML) are not supported for import.
2. Check the file encoding. The file should be UTF-8 encoded. If your file uses a different encoding (e.g., Latin-1), try converting it to UTF-8 first.
3. Check for malformed data. Malformed CSV (unclosed quotes, inconsistent column counts) may cause parsing errors. Try opening the file in a plain text editor to inspect its structure.
4. Try pasting instead. Open the file in a text editor, copy the contents, and paste into DataClean's text area.
5. Check file size. Very large files may take time to parse. Wait a few seconds, or try with a smaller subset of the data.

If the issue persists, please open a GitHub issue on the Sidequest Labs repository with a description of the problem and a sample file if possible.

DataClean maintains an undo history, but there are some limitations:

• Undo is session-based. The undo history is stored in your browser's memory. If you refresh the page or close the tab, the undo history is cleared.
• History depth. DataClean stores a limited number of undo steps. If you have applied many operations, the earliest steps may have been evicted from the history stack.
• Import clears history. Loading a new file resets the undo history since it represents a completely new dataset.

If you need to preserve a specific state, export the data at that point before continuing with further transformations.

DataClean automatically detects your system's color scheme preference and applies light or dark mode accordingly. If dark mode does not appear to be working:

1. Check your OS setting. DataClean follows your operating system's appearance setting (Light/Dark). On macOS, this is in System Settings > Appearance. On Windows, it is in Settings > Personalization > Colors.
2. Check your browser. Some browsers allow overriding the system preference. Ensure your browser is not set to force a specific color scheme.
3. Clear cached data. Try clearing your browser cache for the DataClean site, then reload.
4. Try incognito mode. Open DataClean in an incognito or private window to rule out extension interference.

Custom theme settings (available in Pro) override the system preference. If you previously set a custom theme, you can reset it from the theme picker in the app settings.