Web3, also written Web 3.0, is a model of the internet built on decentralised infrastructure, where applications run on blockchains rather than on servers owned by a single company. In a Web3 application the frontend may still sit on a web server, but the backend logic and data live on a blockchain controlled by its network of users.
Why it matters: The shift from central ownership to a shared blockchain changes what testers need to focus on. Code deployed to a blockchain is very hard to change, so a bug that reaches production may have no rollback. Security and smart contract correctness carry more weight than in a traditional web application.
In practice: Testing a Web3 application still includes the familiar layers: unit, integration, functional, usability and performance testing. On top of that, testers typically:
- Test smart contracts directly, including deployment, transactions and gas fees.
- Use a wallet plugin against a local blockchain to practise real transactions.
- Run security checks for known attacks such as double spending, plus penetration testing before go-live.
- Check interoperability across networks and protocols.
Examples:
- Checking that a token transfer deducts the right amount from a wallet and that the blockchain records the new block.
- Seeing what happens when a user switches networks, adds accounts or imports tokens in the middle of a flow.
- Testing the validation message shown when a request exceeds the token balance in a wallet.
Common pitfalls:
- Assuming that because blockchains are hard to tamper with, the application built on top of them is secure too.
- Treating a release like a Web2 deployment and relying on being able to roll back a faulty smart contract.
What is the difference between Web2 and Web3? In Web2, one organisation owns the frontend, backend and database on its own servers. In Web3, the backend and data sit on a blockchain shared by its users, and only the frontend is hosted centrally.
Do testers need to learn blockchain to test Web3? A working understanding helps a great deal, especially of transactions, wallets and smart contracts, because many of the most serious bugs live there.
