Base64 Encoder & Decoder Online

Base64 Encode Text Online

Encoding converts text into a Base64 string using A–Z, a–z, 0–9, +, and /. Use it when you need to embed binary or special characters in JSON, HTTP headers, or text-only systems. API use cases include auth headers, data URLs, and serialized payloads.

Base64 Decode String Online

Decoding converts a Base64 string back to readable text. Useful for debugging encoded API responses, inspecting auth tokens, or viewing data stored in Base64 format.

Base64 for API Authentication and JSON Data

Basic auth uses Base64 to encode username:password in the Authorization header. Some APIs send Base64-encoded JSON or payloads. Decode here to inspect the content, then validate structure with our JSON Formatter.

Base64 vs Encryption – What's the Difference?

Base64 is encoding, not encryption. It makes data text-safe for transport, but anyone can decode it. For sensitive data, use proper encryption (e.g. AES) and our Password Generator for secure credentials.

Common Base64 Errors and Fixes

Invalid padding usually means extra or missing "=" characters. Remove spaces, line breaks, and non-Base64 characters. Ensure you are using the correct character set (A–Z, a–z, 0–9, +, /). Strip leading or trailing whitespace before decoding.

Is Base64 Encoding Secure?

No. Base64 is not security—it is easily reversible. Never use it to protect passwords, tokens, or confidential data. Use proper encryption for sensitive content.

How to Decode Base64 in JavaScript

In the browser or Node, use the built-in atob() function to decode a Base64 string to a binary string, then decode to UTF-8 if needed.

atob("aGVsbG8=")

Returns the decoded string. For Unicode text, combine with TextDecoder or decode the binary string to bytes first.

How to Encode Base64 in Python

Use the base64 module. Encode bytes with b64encode; decode with b64decode.

import base64
base64.b64encode(b"hello")

For strings, encode to bytes first (e.g. .encode("utf-8")).

Base64 URL Encoding Explained

URL-safe Base64 replaces + with - and / with _ so the string can be used in query params and URLs without escaping. JWTs and many auth libraries use this format. If you see Base64 in URLs or tokens that fails to decode here, try converting - and _ back to + and / first.

Why Is My Base64 String Not Working?

Common causes: Missing padding—Base64 length should be a multiple of 4; add = as needed. Corrupted characters—copy-paste can introduce spaces or line breaks; remove all whitespace. Incorrect format—URL-safe Base64 uses - and _ instead of + and /; convert if your string came from a JWT or URL. Use this decoder to test; for structured payloads, validate with our JSON Formatter after decoding.

What is Base64 encoding and when should you use it?

Base64 is a way to represent binary or text data using only readable characters (A–Z, a–z, 0–9, +, and /). It is commonly used when data has to travel through systems that only handle plain text safely, such as JSON, XML, email, or certain HTTP headers.

Instead of sending raw bytes, you convert the data to Base64, transmit it, and then decode it back to its original form on the other side. This is extremely common in web development, integration work, and debugging.

Common use cases for Base64

• Embedding small images or icons as data URLs in HTML or CSS.
• Sending binary data (such as files) through JSON, XML, or form fields.
• Encoding tokens or credentials for testing (for example, basic auth headers in development tools).
• Storing or logging short pieces of binary or mixed data in a text-only system.

Remember that Base64 is not encryption. If the content is sensitive, you need proper encryption in addition to Base64 or you should avoid putting it in logs and URLs at all.