Base64 Decode

Turn Base64 strings back into readable text, with encoding available for quick checks.

Input
Output
0 characters 0 lines

What does Base64 Decode do?

Base64 Decode turns Base64 strings back into readable text and can also encode text for quick round-trip checks.

  • Primary use: Base64 Decode turns Base64 strings back into readable text and can also encode text for quick round-trip checks.
  • Key technical fact: RFC 4648 Base64 uses A-Z, a-z, 0-9, +, /, and optional = padding.
  • Practical check: Validate the result before using it in authentication, signing, checksum, or transport code.
Topic Direct answer Source
Direct answer Base64 Decode turns Base64 strings back into readable text and can also encode text for quick round-trip checks. IETF RFC 4648
Key fact RFC 4648 Base64 uses A-Z, a-z, 0-9, +, /, and optional = padding. IETF RFC 4648
Processing model Runs locally in the browser; no production Node server receives the input. Browser JavaScript

Decode Base64 into readable text

This Base64 decoder converts encoded strings back into text so you can inspect the original value. Use it to check API responses, email fragments, data URI content, encoded configuration values, JWT segments, or copied payloads that have been wrapped for text transport.

Base64 input commonly uses A-Z, a-z, 0-9, +, /, and optional = padding. Decoding does not verify trust or authenticity; it only reverses the representation when the string is complete and correctly formatted.

How to use

  1. Paste a Base64 encoded string into the input editor.
  2. Click Decode to convert it back to readable text.
  3. Check the output editor and status message. Invalid Base64 input is reported immediately when decoding fails.
  4. Use Copy for the clipboard, Download for a text file, or Clear to reset both editors.

What is Base64 decoding?

Base64 decoding reverses Base64 encoding by mapping printable characters back to the original bytes, then showing those bytes as text when possible. It is a representation step, not a security operation.

Do not treat decoded output as safe just because it was encoded. Base64 can hide scripts, URLs, credentials, or binary bytes in plain sight, so inspect unexpected decoded content before reusing it.

Input notes

Paste only the Base64 string when possible. Remove prefixes such as data:text/plain;base64,, copied labels, markdown fences, or surrounding quotes unless you intentionally want them decoded as part of the input.

Example

A Base64 value can be decoded back into the message it represents:

--- Base64 Encoded Input ---
SGVsbG8sIFdvcmxkIQ==

--- Decoded Output ---
Hello, World!

MCP integration

MCP (Model Context Protocol) lets AI agents and apps discover and run Coding.Tools utilities for repeatable conversions, formatting, hashing, and generation workflows.

MCP tool name: base64-decode

MCP endpoint: https://coding.tools/mcp

Call tools/list first. Each tool entry includes inputSchema, outputSchema, and examples so an AI agent or client can build valid arguments without guessing.

For tools/call, read result.content[0].text for the display value and result.structuredContent for machine parsing. Tool-level failures return isError: true; protocol failures return a JSON-RPC error.

Example tools/call request:

curl -s https://coding.tools/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "MCP-Protocol-Version: 2025-06-18" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"base64-decode","arguments":{"input":"SGVsbG8gZnJvbSBDb2RpbmcuVG9vbHMgTUNQ"}}}'

Most text and data tools accept an input string plus optional options. Browser-only image tools are listed for discovery and return a web UI link when they need browser image APIs.