How Decentralized Exchanges Work: EtherDelta, Kyber Network, and JOYSO Explained

Basic Concepts

Before discussing exchanges, the article introduces essential blockchain concepts: a wallet combines a private key with software/hardware to send and receive crypto; a signature proves that a message originates from the holder of a private key; and a smart contract is a program on the blockchain that is decentralized, transparent, and immutable, capable of holding and exchanging tokens.

Centralized Exchanges (CEX)

Typical CEXs such as Bitfinex, Poloniex, and Coincheck require users to deposit crypto into wallets controlled by the exchange. Trades are recorded only in the exchange’s internal database, not on‑chain, so users must trust the platform to safeguard private keys. This model makes CEXs attractive targets for hackers, as demonstrated by high‑profile thefts.

Decentralized Exchanges (DEX)

DEXs execute trades directly on the blockchain, eliminating the need for the exchange to hold users’ private keys. Transactions are transparent and immutable because the smart contract code is publicly available. The article contrasts the two models with a simple example of swapping 1 ETH for 10 BAT.

EtherDelta

EtherDelta combines on‑chain smart contracts with an off‑chain order book displayed on a website. Users deposit funds into the contract, create orders, and the website lists them. When a counter‑party fulfills an order, both parties send tokens to the contract, which updates balances on‑chain. Advantages include full on‑chain settlement and no private‑key custody by the exchange. Drawbacks are manual order matching, slower transaction throughput due to Ethereum’s latency, and multiple blockchain transactions per trade (deposit, order creation, withdrawal).

Kyber Network

Kyber is a fully on‑chain DEX that does not use an order book. Users call the transfer() function of the Kyber smart contract to swap tokens in a single transaction, receiving immediate execution and lower gas costs. Exchange rates are set by reserve managers, and liquidity providers (reserve contributors) supply tokens for a share of the fees. The design offers fast, atomic swaps but lacks price‑specification features of order‑book models.

JOYSO

JOYSO, a Taiwanese project, adopts a hybrid approach: token custody and balance updates occur on‑chain, while order matching and trade execution are performed by a centralized server. Users sign orders with their private keys; the server matches orders, then an admin account submits the combined transaction to the smart contract. Benefits include automatic matching, faster settlement, and the admin covering gas fees for trade execution, while still preserving on‑chain security of user funds.

Conclusion

Decentralized exchanges leverage blockchain’s decentralization, transparency, and immutability to improve security compared with centralized exchanges, though each DEX design involves trade‑offs. EtherDelta pioneered the space but suffers from manual matching and latency; Kyber offers instant, single‑transaction swaps but no order‑book pricing; JOYSO aims to blend the user experience of CEXs with DEX security by off‑loading matching to a server while keeping funds on‑chain. The article suggests monitoring these projects as the ecosystem evolves.