Date Range (ISO 8601) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching date range (iso 8601), 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

# Date Range (ISO 8601)
# ReDoS-safe | RegexVault — Localization > Date Formats

import re

date_range_iso_8601_pattern = re.compile(r'^((?:19|20)[0-9]{2}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01]))/((?:19|20)[0-9]{2}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01]))$')

def validate_date_range_iso_8601(value: str) -> bool:
    return bool(date_range_iso_8601_pattern.fullmatch(value))

# Example
print(validate_date_range_iso_8601("2024-01-01/2024-12-31"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Date Formats 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

Capture group 1: start date, group 2: end date. This pattern does not validate that the start date precedes the end date — enforce that at application level. ISO 8601 also supports duration syntax (P1Y/2024-01-01) not covered here.