100% Client-Side

Base64 Decoder

Free online Base64 decoder. Decode Base64 encoded strings back to readable text instantly in your browser. Supports standard and URL-safe Base64. — runs 100% in your browser, client-side only. No data is sent to any server. Free to use, no account required.

Free Client-Side No Login No Storage
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Base64 Encoder Encode text or binary data to Base64 — standard and URL-safe variants URL Decoder Decode percent-encoded URLs back to readable query strings Hex Decoder Decode hexadecimal strings back to plain text Binary Decoder Decode binary strings back to readable text

How to Use the Base64 Decoder

  1. Paste a Base64 string into the input field.
  2. Click Decode to convert back to plain text.

Supports both standard and URL-safe Base64 input. The decoder automatically handles missing padding and URL-safe character substitutions.

What is Base64 Decoding?

Base64 decoding reverses the encoding process, converting Base64-encoded ASCII text back to its original binary or text form. The decoder reads groups of 4 Base64 characters and converts them back to 3 bytes of original data.

Why Use This Tool

When you receive Base64-encoded data from APIs, JWT tokens, email attachments, or data URIs, you need to decode it to access the original content. Base64 decoding reveals what was encoded for safe text transmission.

When to Use It

Use Base64 decoding when inspecting JWT header/payload, debugging API responses with encoded fields, extracting images from data URIs, or reading MIME-encoded email attachments.

Common Uses

  • Inspecting JWT token payloads (header and payload are Base64URL-encoded)
  • Decoding images or files embedded as data URIs
  • Debugging API responses that contain Base64-encoded fields
  • Reading Base64-encoded email attachments (MIME format)

Frequently Asked Questions

Why do I get garbled output when decoding?

The original data was binary (like an image or compressed file), not plain text. Base64 can encode any binary data — if the original wasn't text, decoding to text will show garbled characters.

Can I decode a JWT with this tool?

Yes for the header and payload — split the JWT at the dots, take the first or second part, and decode it. The signature (third part) is a cryptographic hash and won't decode to readable text.

Is Base64 decoding safe to do online?

CipherKit runs 100 % in your browser — no data is sent to any server. It is safe to decode sensitive Base64 strings here.