X-Change Guide
Interactive study guide

X-Change, explained from zero.

This site takes you through a real blockchain + cryptocurrency exchange project — a Rust (Axum) node, a Next.js frontend and a PostgreSQL database — and explains every part in plain language, with diagrams and hands-on demos. It is built to prepare you for your project defense: you'll understand not just what the code does, but why each piece exists.

Start with the basics See the architecture
Backend

The Rust node: how it produces blocks, validates transactions, runs the order book and issues JWTs.

Explore
Frontend

The Next.js 15 app: how users create wallets, sign transactions in the browser, trade and stake.

Explore
Database

PostgreSQL: 12 tables that store balances, blocks, transactions, orders and validators.

Explore

One sentence

X-Change is a demo cryptocurrency exchange where users create wallets in their browser, get free test coins from a faucet, send them to each other over a tiny proof-of-stake blockchain, and trade them on an order book — all backed by one Rust server and one PostgreSQL database.

The big picture

Follow the data. Each coloured box is explained on its own page (click to jump).

Browser
Next.js 15 app
wallet • sign • trade • stake
HTTPS / JSON
Node
Rust + Axum server
JWT • blocks • order book
SQL
Postgres
the source of truth
balances • blocks • orders
FrontendBackend nodeDatabase
What makes it special
  • Self-custody wallets — private keys never leave the browser
  • Proof-of-stake consensus — a deterministic, stake-weighted proposer lottery
  • Order-book matching — FIFO price-time priority engine
  • Multisig wallets — N-of-M approvals before funds move
  • Real cryptography — ed25519, SHA-256, SHA3-256, JWT
Stack at a glance
RustAxumTokioSQLxed25519-dalekJWT
Next.js 15React 19TypeScriptTailwindZustandReact Query
PostgreSQL 16DockerRailwayCloudflare Pages

Cryptography is done twice — in Rust and in TypeScript — and the two must agree byte-for-byte. That symmetry is a great defense talking point.

Explore the whole guide

How to use this guide
Read it top to bottom once, then visit each page again while running the actual app. Click every demo — they use the real crypto from the project, so you'll see exactly what the code does. Finish with the quiz to test yourself before the defense.
A note on honesty

This is a demo blockchain. It is a single node that produces blocks on a timer — there is no P2P network of miners, and PostgreSQL is the source of truth. That is completely fine for learning the crypto plumbing, and knowing the difference between a demo chain and a real distributed one (Bitcoin, Ethereum) will make your defense stronger. The defense page covers this honestly.