Inspecting API Payloads, JWT Segments & Auth Headers
Quickly decode Base64 header and payload segments or debug incoming webhook fields without sending sensitive customer data to third-party servers.
Base64 Decoder
Inspect and decode Base64-encoded payloads, API tokens, MIME email segments, and configuration values back into human-readable UTF-8 text. Automatically strips stray line wraps and spaces, reconstructs multibyte Unicode characters and emojis, and alerts you clearly if the input string is corrupted.
How to Use the Base64 Decoder
- 1
Paste your Base64-encoded string into the left input box.
- 2
Inspect the decoded plain-text output rendered immediately in the right box.
- 3
Click Copy Decoded Text to copy the readable result to your clipboard.
- 4
If your Base64 string represents an image file (`data:image/png;base64,...`), use our Base64 to Image tool to render the picture.
Practical Use Cases
Verifying Kubernetes Secrets & Cloud-Init Scripts
Check the actual plain-text value stored inside a Base64-encoded Kubernetes secret or Terraform user-data block before deploying.
Reading Raw MIME Email Bodies
Decode `Content-Transfer-Encoding: base64` blocks from raw `.eml` source files to read the underlying HTML or plain-text message.
Base64 Decoder Features
Multi-Line Whitespace Tolerance
Ignores 76-character MIME line wraps and stray spaces automatically.
Full UTF-8 Unicode Reconstruction
Restores international characters, JSON structures, and emojis without garbled mojibake.
Instant Syntax Validation
Flags invalid non-Base64 characters or truncated strings clearly.
Runs 100% in your browser
Nothing is uploaded to a remote server, so your data and files stay strictly on your device.
Free and unlimited
No account registration, no watermarks, and no daily usage caps.
Mobile and desktop ready
Responsive layouts and comfortable touch controls that fit phones, tablets, and desktops.
Technical Specifications & Best Practices
- ✓Automatically strips line breaks and whitespace inside multi-line MIME Base64 blocks before decoding.
- ✓Decodes bytes through `TextDecoder('utf-8')` so accented characters, symbols, and emojis are restored intact.
- ✓If you are decoding a binary image rather than text, use our dedicated Base64 to Image tool to preview and download the graphic.
- ✓100% client-side execution — confidential tokens and payloads stay in your browser.