Swiss Postleitzahl (PLZ) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching swiss postleitzahl (plz), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Swiss Postleitzahl (PLZ)
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

swiss_postleitzahl_plz_pattern = re.compile(r'^([1-9][0-9]{3})$')

def validate_swiss_postleitzahl_plz(value: str) -> bool:
    return bool(swiss_postleitzahl_plz_pattern.fullmatch(value))

# Example
print(validate_swiss_postleitzahl_plz("1000"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Swiss PLZ ranges: 1000-1999 (Vaud/Romandy), 2000-2999 (Neuchâtel/Jura), 3000-3999 (Bern), 4000-4999 (Basel), 5000-5999 (Aargau), 6000-6999 (Lucerne/Ticino), 7000-7999 (Graubünden), 8000-8999 (Zurich), 9000-9999 (St. Gallen/Appenzell).