🔄 Mode
📝 Input
✅ Output
Pure Frontend · Text to Base91 and Back · Real-Time Preview · Batch Processing
Zero Dependencies · Works OfflineThe Base91 Encoder/Decoder is a pure frontend online tool for converting between text and Base91 encoding. Base91 is an efficient binary-to-text encoding scheme using 91 printable ASCII characters with ~81.1% encoding efficiency, higher than Base64's 75%. All operations happen locally in the browser.
Step 1: Select encode or decode mode.
Step 2: Paste text or Base91 string in the input area, or click "Load Example".
Step 3: View real-time output results.
Step 4: Click "Copy Result" or "Download" to get the output.
When encoding binary data as text for transmission, Base91 produces shorter output than Base64, ideal for bandwidth-sensitive scenarios.
Quickly verify Base91 encoding/decoding results when working with Base91-encoded data.
Compare encoding efficiency between Base91, Base64, Base32, and Hex.
Use Base91 encoding to reduce storage overhead in space-constrained embedded systems.
Base91 was designed by Joachim Henke. It uses 91 printable ASCII characters (excluding -, \, and '). The algorithm encodes 13 bits of data into 2 characters, achieving efficiency of log₂(91)/8 ≈ 0.811. Compared to Base64 which encodes 3 bytes into 4 characters (75% efficiency), Base91 produces shorter output for the same data. The Base91 alphabet is ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!#$%&()*+,./:;<=>?@[]^_`{|}~".
Base91 uses 91 printable ASCII characters with ~81.1% encoding efficiency, higher than Base64's 75%. Base91 is better for size-sensitive scenarios but slightly more complex.
Supports text and hexadecimal input modes. Encoding converts text/Hex to Base91, decoding converts Base91 back to text/Hex.
No. All encoding/decoding happens locally in the browser. Your data never leaves your device.
Yes. Multi-line input with each line processed independently.
Base91 produces shorter encoded output for the same data, ideal for size-sensitive scenarios like URL parameters and email attachments.
Yes. One-click copy to clipboard or download as a text file.