Base64デコード
Base64文字列をプレーンテキストにデコードします（UTF-8対応）。Base64値を1つ以上貼り付け——各行が個別にデコードされます。
入力
複数ある場合は、各Base64文字列を別の行に貼り付けてください。
出力
注意: デコードされた内容は慎重に取り扱ってください——機密性が高い、または実行可能な場合があります。
ガイド
What is Base64?
Base64 is an encoding that represents binary data using 64 safe ASCII characters (A–Z, a–z, 0–9, +, /). It's everywhere: email attachments, data URLs, JWT tokens, API payloads and configuration files. It is encoding, not encryption — anyone can reverse it, which is exactly what this tool does.
How to use it
- Paste a Base64 string into the input (whitespace and line wrapping are tolerated).
- Hit Decode — the plain-text result appears on the right, with full UTF-8 support for accents, emoji and non-Latin scripts.
- Decode several values at once by putting each on its own line.
When you'd reach for it
- Inspecting the payload of a JWT segment or an API response field.
- Reading Base64 blocks in email source or
.env/YAML configs. - Checking what's inside a data URL before trusting it.
Caution: decoded content can be sensitive or executable — handle it accordingly.
Privacy
Decoding happens entirely in your browser; your data never touches a server.
Use it from code
From 3 credits per callREST API
curl -X POST https://api.iotools.cloud/v1/tool/base64-decode \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"base64String": "SGVsbG8gV29ybGQh"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `base64-decode` tool (Base64 Decode) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
ワークフローの一部
すべてのコレクションEighteen tools for the things people mix up daily — encoding versus encryption, which hash belongs on a password, and what an HMAC is actually for. Everything runs in your browser, so nothing you paste is uploaded.
Thirty-one tools for everything a URL can become: its raw HTML, clean text, Markdown, structured JSON or XML, a screenshot, a PDF, or a QR code — plus tools to inspect its meta tags, heading outline, links, and IP addresses without opening it. Every live-fetch tool here runs server-side, so it works even on sites that block cross-origin requests from a browser. Round it out with a combined multi-scheme encoder/decoder and the focused single-purpose tools underneath it.