What is data masking and why is it needed?

Data masking is the process of obscuring or replacing sensitive information (such as phone numbers, ID numbers, etc.) to protect privacy, comply with regulations, hide real data in test environments, prevent user information leaks in logs/debugging, and protect sensitive fields during data sharing.

What masking strategies are supported?

The tool supports five masking strategies: 1) Keep first & last, middle * (default, e.g. 138****8000); 2) Keep first N (e.g. 1380*****); 3) Keep last N (e.g. *****8000); 4) Replace all with * (e.g. ***********); 5) Custom keep positions (e.g. keep positions 0,1,2,-4,-3,-2,-1). Each sensitive field type can be configured independently.

How does auto-detection work?

When "Auto-detect sensitive fields" is enabled, the tool uses regular expressions to match sensitive patterns in JSON values: phone numbers match 11-digit numbers starting with 1, ID cards match 18-digit numbers or ending with X, emails match standard email format, names match 2-4 consecutive Chinese characters, etc. It also matches field names (e.g. phone, idCard) to corresponding masking rules. The combination covers most use cases.

Is my data secure? Is it uploaded to a server?

Completely secure. All data processing is done locally in your browser (pure frontend JavaScript). No requests are sent to any server. You can use this tool even while offline. The tool is open source and auditable, containing no network request code.

Data Mask

Automatically mask private data

Text Input File Upload Auto-detect sensitive fields

Input JSON Data

Mask Rules (Select field types and rules to mask)

📱 Phone

Example:13800138000→138****8000

🪪 ID Card

Example:110101199001011234→1101********1234

📧 Email

Example:zhangsan@example.com→zh****@example.com

👤 Name

Example:张三→张*

before chars

💳 Bank Card

Example:6222021234567890123→6222*********0123

📍 Address

Custom Field Mapping (Which JSON field names map to which type, comma-separated)

📱 Phone：

🪪 ID Card：

📧 Email：

👤 Name：

💳 Bank Card：

📍 Address：

Data Mask Tool Guide

Features

Auto-detect - Intelligently identifies phone numbers, ID cards, emails, and other sensitive fields
Multiple masking strategies - Keep first/last, middle masking, full replacement, etc.
Batch processing - Supports JSON array batch masking
Custom mapping - Customize field-to-type associations
Side-by-side preview - Compare original and masked data
Local processing - All data is processed locally in your browser, never uploaded to a server

Supported Sensitive Types

📱 Phone - 11-digit phone number masking
🪪 ID Card - 18-digit ID card masking
📧 Email - Email address masking
👤 Name - Chinese name masking
💳 Bank Card - Bank card number masking
📍 Address - Detailed address masking