Base64 Decode Online
Paste any Base64 value and this Base64 decoder works out the rest: it detects the Base64 variant (standard, URL-safe, MIME and others), the character set of text, and the file type of binary data. Text is shown directly; files get a preview and a download button.
How to use the Base64 Decode Online tool
- Paste the Base64 string (data URIs, line breaks and spaces are fine).
- Leave the standard and charset on Auto-detect, or choose them manually.
- Enable strict mode if you want invalid characters to raise an error instead of being skipped.
- Click Decode Base64.
Why does the decoder accept invalid characters?
Base64 copied from e-mails, logs or PDFs often contains stray spaces, quotes or line numbers. In the default (lenient) mode the decoder ignores anything outside the Base64 alphabet and fixes missing padding, which is what most real-world decoders do too. Turn on strict mode to validate the input exactly against the selected standard.
Character encodings
When the decoded bytes are text, the decoder tries UTF-8 first and then common legacy encodings (Windows-1252, ISO-8859-x, Shift_JIS, GBK, EUC-KR, Big5, KOI8-R and more), choosing the one that produces readable text. You can force a specific charset from the list.
When developers decode Base64
Use this free Base64 decoder to inspect API payloads, open data URIs, read JWT segments (with the JWT tool for full tokens), recover files from logs, and verify MIME or PEM bodies. Auto-detect handles standard and URL-safe alphabets so you spend less time guessing which variant produced the string.
All Base64 encoders
- Text to Base64
- File to Base64
- Image to Base64
- PNG to Base64
- JPG to Base64
- GIF to Base64
- BMP to Base64
- ICO to Base64
- SVG to Base64
- WebP to Base64
- AVIF to Base64
- Audio to Base64
- MP3 to Base64
- WAV to Base64
- Ogg to Base64
- FLAC to Base64
- WMA to Base64
- Video to Base64
- PDF to Base64
- Hex to Base64
- HTML to Base64
- CSS to Base64
- JSON to Base64
- URL to Base64
All Base64 decoders
Frequently asked questions
How do I decode Base64?
Paste the Base64 string into the input and click "Decode Base64". Text is displayed immediately; binary files can be previewed and downloaded.
Why do I get "invalid character" errors?
Your string contains characters outside the selected alphabet, such as "-" or "_" from Base64URL. Use Auto-detect, switch off strict mode, or run it through the Base64 repair tool.
Can I decode Base64 to an image or PDF?
Yes. If the decoded data is a file, the decoder recognises its type and shows a preview with a download button.
Is this Base64 decoder free and private?
Yes. Decoding runs in your browser. Your string is not uploaded or stored. There is no account and no fee.
How do I decode Base64URL or JWT-style strings?
Leave Auto-detect on, or choose Base64URL. For full JWTs (three dot-separated segments), use the JWT Decoder tool which Base64URL-decodes the header and payload.
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