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Data Masker

Anonymize PII in JSON and CSV files with configurable masking strategies including redaction, hashing, partial masking, and fake data generation.

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> Input Data

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Drop a JSON or CSV file
Or paste data below

What is Data Masker?

Data Masker is a free, browser-based tool that detects and anonymizes personally identifiable information (PII) in JSON and CSV files. It automatically scans field names and values to identify emails, phone numbers, SSNs, IP addresses, credit card numbers, names, and more. Choose from four masking strategies — Redact, Hash (SHA-256), Partial Mask, or Fake Data — per field, then download the anonymized file in its original format. All processing runs entirely in your browser.

Common Use Cases

GDPR Compliance

Anonymize personal data in datasets before sharing or storing to meet GDPR, CCPA, and other privacy regulation requirements.

Test Data Preparation

Mask production data to create realistic but safe test datasets for QA and development environments.

Data Sharing

Remove sensitive fields from CSV or JSON exports before sharing with third parties, partners, or in public datasets.

Development Environments

Generate anonymized copies of production databases for local development without exposing real customer information.

How to Use This Tool

  1. Paste a JSON array or CSV data into the text area, or drag and drop a .json or .csv file onto the upload zone
  2. Review the auto-detected PII fields in the detection panel — each shows the field name, PII type, and a sample value
  3. Choose a masking strategy (Redact, Hash, Partial Mask, or Fake Data) for each detected field using the dropdown
  4. Click the "Mask Data" button to apply the selected strategies to all rows
  5. Preview the side-by-side comparison, then copy to clipboard or download the masked file

Frequently Asked Questions

Is my data sent to any server?
No. All processing runs entirely in your browser using JavaScript. Your data never leaves your machine.
What PII types does it detect?
The tool detects emails, phone numbers, SSNs, IP addresses, credit card numbers, names, addresses, and dates of birth — both by scanning field names and by analyzing value patterns.
What is the difference between the masking strategies?
Redact replaces the value with [REDACTED]. Hash produces a consistent SHA-256 hash prefix (useful for joining datasets). Partial Mask keeps parts of the value visible (e.g., j***@example.com). Fake Data generates realistic but fictional replacement values.
Can I use different strategies for different fields?
Yes. Each detected PII field has its own strategy dropdown, so you can redact SSNs while partially masking emails and generating fake names.

Related Tools

Secret Scanner → Fake Data Generator →

Learn More

Data Masker is a free online tool that requires no signup or installation. It works directly in your browser, keeping your data private and secure.