SCALE Compact Encoder / Decoder (Node.js)

A simple and accurate SCALE Compact Integer decoder implementation in Node.js — built from scratch to help understand and work with SCALE encoding used in Substrate-based blockchains (like Polkadot, Kusama, etc.).

• A set of interactive CLI tools to encode and decode SCALE compact integers — used in blockchains.

🚀 Features

• Encodes / Decodes SCALE compact-encoded integers (all 4 modes: single-byte, two-byte, four-byte, big-integer).
• Fully little-endian aware.
• Helpful debug logs for educational purposes.
• Interactive CLI tool for learners
• Designed for manual testing and prototyping.

📦 Installation

Clone the repository:

git clone https://github.com/pallasite99/scale-nodejs.git
cd scale-nodejs

Usage (basic example)

node scale.js

Example Output (Decoding)

Parsed bytes: <Buffer 04>
Decoded 0x04 => 1

Parsed bytes: <Buffer 08>
Decoded 0x08 => 2

Parsed bytes: <Buffer fc>
Decoded 0xfc => 63

Parsed bytes: <Buffer fc 01>
Decoded 0xfc01 => 127

Supported SCALE Compact modes

| Mode Bits | Bytes Used | Max Value | Description        |
|-----------|------------|-----------|--------------------|
| `00`      | 1 byte     | up to 63  | Single-byte mode   |
| `01`      | 2 bytes    | up to 16K | Two-byte mode      |
| `10`      | 4 bytes    | up to 1B  | Four-byte mode     |
| `11`      | N+5 bytes  | BigInt    | Big-integer mode   |

Local CLI usage

node ./bin/scale-decode.js
node ./bin/scale-encode.js

CLI support (Global npm link)

Running local WebApp

1. Navigate to scale-web directory
2. Run npm run dev command after installing all dependencies via npm install in scale-web directory
3. Visit 'localhost:5173' to interact with React + Vite WebApp

Web UI