Parse WHOIS Data with Python Regex

Extract domain registration fields from a mock WHOIS record using regex and compute days until expiration.

Easy Python 3.9+ Aug 9, 2026 Automation & scripting 12 views 0 copies

whois regex parsing automation datetime

Python code

39 lines

Python 3.9+

import re
from datetime import datetime


def parse_whois(whois_text: str) -> dict:
    """Extract key registration fields from a mock WHOIS record."""
    patterns = {
        "domain": r"Domain Name:\s*(.+)",
        "registrar": r"Registrar:\s*(.+)",
        "creation_date": r"Creation Date:\s*(.+)",
        "expiry_date": r"Expiry Date:\s*(.+)",
        "status": r"Status:\s*(.+)",
    }
    parsed = {}
    for key, pattern in patterns.items():
        match = re.search(pattern, whois_text, re.IGNORECASE)
        if match:
            parsed[key] = match.group(1).strip()
    return parsed


def days_until_expiry(expiry_date_str: str) -> int:
    """Return days remaining until domain expiry."""
    expiry = datetime.strptime(expiry_date_str, "%Y-%m-%d")
    return (expiry - datetime.now()).days


if __name__ == "__main__":
    mock_whois = """Domain Name: example.com
    Registrar: Mock Registrar LLC
    Creation Date: 2015-06-01
    Expiry Date: 2025-06-01
    Status: clientTransferProhibited"""

    info = parse_whois(mock_whois)
    print(f"Domain: {info['domain']}")
    print(f"Registrar: {info['registrar']}")
    print(f"Expires in: {days_until_expiry(info['expiry_date'])} days")
    print(f"Status: {info['status']}")

Output

stdout

Domain: example.com
Registrar: Mock Registrar LLC
Expires in: 342 days
Status: clientTransferProhibited

How it works

The parse_whois function uses named regex patterns to capture key fields from the WHOIS text. The re.IGNORECASE flag makes matching case-insensitive. datetime.strptime converts the expiry date string into a datetime object for comparison with datetime.now(). The main block formats and prints the extracted information alongside the days remaining until expiration.

Common mistakes

Forgetting to use `re.search` vs `re.match`, which anchors matching to the start
Assuming date formats are consistent across all registrars
Not stripping whitespace from matched groups, leading to unclean values

Variations

Use `re.compile` to precompile patterns for repeated calls
Parse WHOIS data with `whois` library for real domain lookups

Real-world use cases

Automating domain portfolio monitoring to flag upcoming expirations for renewal.
Building an internal tool that audits registrars and domain statuses across a company.
Integrating WHOIS parsing into a script that validates domain ownership for certificate issuance.

Parse WHOIS Data with Python Regex

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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