When I first switched from Web2 to Web3, I thought,
“It’s just UI and API testing, right?”
But, I realized I had stepped into a completely different world.
Here are the biggest differences that every QA needs to understand before testing blockchain apps.
🔐 1. Immutable Data
In Web2, we can roll back, reset test data, or fix mistakes easily.
In Web3? Not possible.
- Every transaction is permanent on the blockchain.
- One small bug in a smart contract can cause real money loss.
- No "admin" to change data.
💡 Lesson: Be extra careful when testing anything that writes to the blockchain.
🌐 2. Decentralized Architecture
No more single backend with easy logs or debugging.
Web3 systems have many parts:
- UI: runs in browser
- Wallet: signs & sends transactions (e.g., MetaMask)
- Smart Contract: runs on-chain logic
- Node/Provider: connects to blockchain (Infura, Alchemy...)
- Subgraph/Indexer: stores & queries blockchain data
💡Lesson: Bugs can happen anywhere in this stack. As a QA, you need to understand the full picture.
⛽ 3. Gas fee
Every on-chain action costs gas (real crypto, even on testnet).
- Need ETH (testnet) to run tests
- Spamming tests = run out of gas = testing stops
- Performance testing must consider gas cost
💡 Lesson: Plan your tests carefully to avoid wasting resources. And check gas usage in your test cases.
⚙ 4. Smart Contracts ≠ Normal Backend
Smart contracts cannot be modified after deployment (unless a proxy is used). The logic handling is also very different from the backend API:
💡 Lesson: Don't just check the result. Understand the contract logic too. Sometimes it “works” but is badly designed.
🔄 5. On-chain vs Off-chain Testing
Not all data is on the blockchain.
- On-chain: balances, transactions, smart contract state
→ Test using explorers, Hardhat, JSON-RPC
- Off-chain: UI state, indexers, caches
→ Test using Postman, browser tools, etc.
💡 Lesson: UI testing is not enough. Use blockchain tools to see the full picture.
🧩 Final Thought
Testing in Web3 is more than just checking UI or APIs.
It’s about understanding a decentralized system—where bugs can affect real assets, real users, and can’t be undone.
The first step to becoming a good Web3 QA isn’t learning tools — it’s fixing the mindset bug.
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