Ethereum Checksummed Address (EIP-55) Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching ethereum checksummed address (eip-55), ported and verified for Python. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. 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

# Ethereum Checksummed Address (EIP-55)
# ReDoS-safe | RegexVault — Finance > Crypto

import re

ethereum_checksummed_address_eip55_pattern = re.compile(r'^0x(?:[0-9A-F]{40}|[0-9a-f]{40}|(?:[0-9a-fA-F]{40}))$')

def validate_ethereum_checksummed_address_eip55(value: str) -> bool:
    return bool(ethereum_checksummed_address_eip55_pattern.fullmatch(value))

# Example
print(validate_ethereum_checksummed_address_eip55("0xAb8483F64d9C6d1EcF9b849Ae677dD3315835cb2"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Crypto 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

EIP-55 checksum embeds a SHA3 hash of the lowercase address in the casing of the hex letters. A correctly checksummed address has mixed case. Regex alone cannot verify EIP-55 — use a library. This pattern just validates the format.