Base64 Encoder/Decoder

Encode text to Base64 or decode Base64 back to text.
Mode

Result

SGVsbG8sIFdvcmxkIQ==

Details

Input Characters13
Output Characters20
Input Size13 bytes
Output Size20 bytes

Use the Base64 Encoder/Decoder above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

This Base64 Encoder/Decoder tool allows you to convert plain text into its Base64 encoded representation and vice-versa. Base64 encoding is widely used in 2026 for transmitting binary data over mediums that primarily handle text, such as email attachments, web APIs, and embedded images in HTML documents. It ensures data integrity by preventing corruption during transmission.

The encoding process takes 3 bytes of input data, converts them into 24 bits, and then splits these 24 bits into four 6-bit blocks. Each 6-bit block is then mapped to a character in the Base64 character set (A-Z, a-z, 0-9, +, /). Padding characters (=) are added if the input length is not a multiple of 3. Decoding reverses this process, converting Base64 characters back into their 6-bit representations, reassembling them into 8-bit bytes, and forming the original data.

A common mistake is forgetting that Base64 encoding increases the data size by approximately 33%, which can impact bandwidth and storage. Also, ensure you're using the correct character set; standard Base64 uses '+/' while URL-safe Base64 uses '-_'. Incorrect decoding due to character set mismatches is a frequent source of errors in 2026 API integrations.

Decoding an API Key

  1. 1 Input: 'U2VjcmV0QVBJS2V5MjAyNkFGVEhJU0lTQ09ERURVU0VSRk9SQVBJIQ=='
  2. 2 The calculator will process the Base64 string, converting each character back to its 6-bit representation, then grouping these bits into 8-bit bytes. Padding characters ('=') will be removed during this process.
  3. 3 Result: 'SecretAPIKey2026AFTERTHISISCODEDUSERFORAPI!'
  4. 4 This decoded string represents a hypothetical API key for a 2026 service. In real-world scenarios, developers often encode API keys or other sensitive data in Base64 before transmitting them in HTTP headers or configuration files to avoid issues with special characters and ensure safe transport.

Source: IETF · Last updated: April 2026

Frequently Asked Questions

What is Base64 encoding used for?
Base64 encodes binary data as ASCII text so it can be safely transmitted in text-based formats like email, JSON, URLs, and HTML. It is commonly used for embedding images in CSS/HTML and encoding API authentication tokens.
Does Base64 encoding provide security?
No. Base64 is an encoding, not encryption. Anyone can decode Base64 text instantly. Never use Base64 to protect sensitive data like passwords or API keys. Use proper encryption (AES, RSA) for security.
Why does Base64 make data larger?
Base64 increases data size by approximately 33% because it converts every 3 bytes of binary data into 4 ASCII characters. This tradeoff is accepted because the encoded data is safe for text-based transport.

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