Base64 to Text Converter
Decode Base64 payloads into readable text or encode plain text to Base64 in real time. Built-in UTF-8 decoder handles emojis, international characters, URL-safe variants, and automatic padding repair.
Engine Capabilities & Technical Highlights
Full UTF-8 Unicode Decoding
Eliminates atob() byte truncation. Fully supports international language characters, accented vowels, and emojis.
URL-Safe Variant Support
Encodes and decodes URL-friendly Base64 where "+" and "/" are safely substituted with "-" and "_".
Automatic Padding Healing
Automatically calculates missing "=" padding characters to recover truncated or unpadded base64 inputs.
Two-Way Encode & Decode
Easily switch from Base64 to text or plain text to Base64 with a single click in the top toolbar.
Strict RFC Validation
Validates characters against the RFC 4648 specification and displays inline errors for malformed sequences.
Local Browser Sandbox
Executes 100% on the client side with zero telemetry, keeping your API tokens and credentials confidential.
RFC 4648 Base64 Alphabet Index Table
How 6-bit binary integer values are mapped into ASCII representation.
| Index Value (Decimal) | Characters Mapped | 6-Bit Binary Range |
|---|---|---|
| 0–25 | A – Z | 000000 – 011001 |
| 26–51 | a – z | 011010 – 110011 |
| 52–61 | 0 – 9 | 110100 – 111101 |
| 62 | + (or - in URL-Safe) | 111110 |
| 63 | / (or _ in URL-Safe) | 111111 |
| Padding | = | Zero-fill pad |
How to Decode Base64 to Plain Text
Paste Base64
Paste your Base64 encoded string into the input pane. Whitespace and newlines are cleaned automatically.
Instant Decoding
The tool immediately processes binary byte chunks and translates them to human-readable text via UTF-8.
Copy Text
Click "Copy to Clipboard" to transfer your decoded message into your editor or terminal.
Frequently Asked Questions
How does Base64 encoding and decoding work?
Base64 is a binary-to-text encoding scheme defined by RFC 4648. It takes groups of 3 bytes (24 bits) and divides them into 4 segments of 6 bits each. Each 6-bit segment maps to one of 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). Decoding reverses this operation, turning 4 characters back into the original 3 raw bytes.
Why do other online Base64 decoders fail with Unicode or emojis?
Many simplistic web tools use standard window.atob(), which interprets binary strings strictly as Latin-1 (ISO-8859-1). When encountering multi-byte UTF-8 sequences (like emojis or non-Latin alphabets), standard atob crashes or outputs corrupted mojibake characters. Our converter uses native Uint8Array and TextDecoder("utf-8") pipelines to guarantee 100% fidelity for all global Unicode scripts.
What is URL-Safe Base64?
Standard Base64 contains the characters "+" and "/", which have special reserved meanings in web URLs and filenames. URL-Safe Base64 replaces "+" with "-" (hyphen) and "/" with "_" (underscore), and optionally strips trailing "=" padding characters so the string can be safely passed inside query parameters or path segments without percent-encoding.
What causes "Invalid Base64 sequence" errors?
This error happens when the input contains illegal characters not present in the 64-character alphabet, or when the string length is not a multiple of 4 and cannot be safely padded. Our tool automatically strips extraneous whitespace and attempts auto-padding, flagging any invalid tokens with an inline error message.
Is it safe to decode private tokens, API keys, or JWTs here?
Yes. Conversion execution occurs entirely inside your local browser thread using pure client-side JavaScript. No data, payloads, or credentials are sent over the network or stored in server logs.
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