Base64 String Compare

Compare two Base64 strings side by side. See if they decode to the same content and find character-level differences.

Last Updated: September 2026

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Base64 String A

Base64 String B

Enter two Base64 strings above and click Compare

Compare Base64 in Code

Check if two Base64 strings represent the same decoded content.

Python

import base64

def compare_base64(a: str, b: str) -> dict:
    result = {
        "same_string": a == b,
        "same_content": False,
        "differences": []
    }
    try:
        decoded_a = base64.b64decode(a)
        decoded_b = base64.b64decode(b)
        result["same_content"] = decoded_a == decoded_b
        # Find character-level differences
        for i, (ca, cb) in enumerate(zip(a, b)):
            if ca != cb:
                result["differences"].append(
                    f"Position {i}: '{ca}' vs '{cb}'"
                )
        if len(a) != len(b):
            result["differences"].append(
                f"Length mismatch: {len(a)} vs {len(b)}"
            )
    except Exception as e:
        result["error"] = str(e)
    return result

print(compare_base64("SGVsbG8=", "SGVsbG8="))
# {'same_string': True, 'same_content': True, 'differences': []}

Frequently Asked Questions

Search below or browse through our most commonly asked questions.

The tool decodes both strings and compares their raw binary content, allowing it to determine if they represent the exact same underlying data even if their text formatting differs.

Different encoders might handle line breaks (MIME format), padding, or character sets differently. Our compare tool will highlight exact character mismatches.