Validation Rules & Standards

Explore all the validation rules we currently support and see examples of how we process different data formats. Learn about automatic fixes and understand what makes data valid or invalid.

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Phone Numbers

UK mobile and landline phone number validation with automatic formatting

How It Works

We take your phone number input and automatically check it against UK phone number standards. Our system detects the type of number, validates the format, and applies automatic fixes to ensure consistency. We can handle most common formatting issues automatically, but some cases require manual correction.

What We Check

✓ Number length and structure
✓ Country code format (+44)
✓ UK domestic format (0)
✓ Mobile vs landline patterns
✓ Area code validity
✓ Spacing and formatting consistency
✓ Labels, icons, and descriptive text
✓ Extension-style clutter
✓ Quotes and wrapping characters
✓ Weird separators and whitespace

Automatic Fixes We Apply

Format Standardization

Convert between international (+44) and UK (0) formats

07700 900123 → +44 7700 900123
+44 7700 900123 → 07700 900123

Country Code Correction

Fix missing or incorrect country codes

7700 900123 → +44 7700 900123
0044 7700 900123 → +44 7700 900123

Spacing and Punctuation

Standardize spacing and remove unnecessary characters

+44 (0) 7700 900123 → +44 7700 900123
07700-900-123 → 07700 900123

Label and Icon Removal

Remove common prefixes, suffixes, and emojis

Mobile: 07700 900123 → +44 7700 900123
📱+44 7700 900123 → +44 7700 900123

Supported Formats

Mobile Numbers

7xxxxxxxxx

10-digit numbers starting with 7 (mobile phones)

07700 900123 7700 900123 +44 7700 900123

Landline Numbers

0xxxxxxxxx

11-digit numbers starting with 0 (landlines)

020 7946 0958 02079460958 +44 20 7946 0958

Output Format Options

Choose how you want your phone numbers formatted in the results:

International (+44)

Always includes +44 country code

+44 7700 900123

UK (0)

UK domestic format starting with 0

07700 900123
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National Insurance Numbers

UK National Insurance number validation and formatting

How It Works

We validate UK National Insurance numbers by checking their format structure and applying automatic corrections for common issues.

What We Check

✓ Format structure (2 letters + 6-8 digits + optional letter)
✓ Letter and digit combinations
✓ Spacing and formatting
✓ Case sensitivity

Supported Formats

Standard Format

AB123456C

2 letters + 6 digits + 1 letter

AB123456C AB 123456 C ab123456c

HMRC Compliance Standards

Your NI numbers are validated against official HMRC standards. Common rejection reasons:

  • • Banned prefixes: BG, GB, KN, NK, NT, TN, ZZ
  • • Invalid letters: D, F, I, Q, U, V in first position; O in second position
  • • TRN format: 11 a1 11 11 (not a valid NI number)
  • • Administrative prefixes: OO, FY, NC, PZ (special use only)
📍

UK Postcodes

UK postcode validation with automatic formatting

How It Works

We validate UK postcodes by checking their structure and applying automatic formatting corrections.

Supported Formats

Standard Postcode

A9 9AA

1 letter + 1 digit + space + 1 digit + 2 letters

M1 1AA B33 8TH

London Postcode

A9A 9AA

1 letter + 1 digit + 1 letter + space + 1 digit + 2 letters

SW1A 1AA W1A 1AA
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Bank Sort Codes

UK bank sort code validation and formatting

How It Works

We validate UK bank sort codes by checking their digit structure and applying automatic formatting.

Supported Formats

Standard Format

xx-xx-xx

6 digits with dashes between pairs

12-34-56 23-45-67

Compact Format

xxxxxx

6 digits without separators

123456 234567

🚀 Coming Soon: More Data Types

We're constantly expanding our validation capabilities. Here are some data types we're planning to add:

📧

Email Addresses

Email validation with domain checking and format verification

planned
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UK Driving Licenses

UK driving license number validation and format checking

planned
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UK Passport Numbers

UK passport number validation and format verification

planned