Base64 Encoder/Decoder

How to Use the Base64 Encoder/Decoder

This free online Base64 encoder and decoder lets you convert text to Base64 or decode Base64 strings back to readable text instantly in your browser. Base64 encoding transforms binary data into a safe ASCII string format using 64 characters (A–Z, a–z, 0–9, +, /), making it essential for embedding data in URLs, emails, JSON payloads, and HTML documents.

Step-by-Step

1. **Paste or type** your text into the input field.

Choose your mode — click Encode to convert plain text to Base64, or Decode to convert a Base64 string back to plain text.

Copy the result — use the Copy button to grab the output instantly.

The tool auto-detects whether your input looks like a valid Base64 string and suggests the appropriate mode.

Features

Encode text to Base64 — Convert any UTF-8 string into Base64 representation.

Decode Base64 to text — Reverse the encoding to reveal the original content.

Instant processing — Results appear as you type with zero delay.

Error detection — Invalid Base64 input is flagged with a clear error message.

One-click copy — Copy the output to your clipboard with a single click.

Privacy first — All encoding and decoding uses the browser's native btoa and atob functions. No data is sent to any server.

Common Use Cases

API Authentication — Many APIs use Base64-encoded credentials for Basic Auth headers. Encode username:password to create the header value, or decode an existing token to inspect it.

Data URIs — Embed small images or fonts directly in HTML or CSS using Base64 data URIs like data:image/png;base64,....

JWT Debugging — JWT tokens contain Base64url-encoded header and payload segments. Decode them to inspect claims, expiration times, and issuer information.

Email Encoding — MIME email attachments are Base64-encoded. Decode them to verify content or debug email delivery issues.

Configuration Files — Kubernetes secrets, CI/CD environment variables, and cloud configs often store values as Base64. Decode them to audit what's actually stored.

Tips for Power Users

- Base64 increases string size by approximately 33%. Keep this in mind when encoding large payloads.

- For URL-safe Base64, replace + with - and / with _ after encoding — many APIs require this variant.

- Use this tool alongside the JWT Decoder for a complete token inspection workflow.

- Bookmark the tool for quick access — it works offline once loaded since everything runs client-side.

Why Use This Tool?

Unlike server-based Base64 tools, this encoder/decoder runs entirely in your browser using native JavaScript functions. Your data never leaves your device — there are no API calls, no logging, and no third-party dependencies. It's fast, free, and completely private. Whether you're debugging authentication headers, creating data URIs, or inspecting encoded configuration values, this tool gives you instant results with zero risk.