Submit a Review
Your review will be mined into an immutable blockchain block and broadcast worldwide.
Verify Chain
Re-hash every block and check all links.
⚠ Tamper Simulation
Demonstrate blockchain immutability.
Result: Chain verification instantly detects the hash mismatch and flags the block as INVALID — proving data cannot be silently changed.
ReviewChain
Decentralized Product Review System · Final Year Project · Blockchain Technology
ReviewChain applies blockchain principles to eliminate fake reviews. Every review is SHA-256 hashed, proof-of-work mined, and stored as an immutable block in a chain synced globally via Gun.js peer-to-peer network — with no central authority, no server, and no way to quietly manipulate data.
Blockchain Database
Instead of a SQL database, reviews are stored in cryptographically linked blocks. Each block contains the previous block's hash — making the entire history tamper-evident.
Proof of Work
The browser must find a nonce such that SHA-256(data + nonce) starts with required zeros. This is real Bitcoin-style computational proof-of-work.
SHA-256 Hashing
Every block is hashed using the browser's native SubtleCrypto API — the same algorithm used by Bitcoin. One character change → completely different hash.
Gun.js P2P Sync
Reviews are broadcast to all users worldwide via Gun.js — an open-source, serverless peer-to-peer database. No central server, no subscription, no company owns the data.
Permanent Wallet
Each reviewer gets a cryptographically generated wallet address unique to their browser — derived from canvas fingerprint + a random salt. One browser, one wallet, forever.
Immutability
Modifying any past review changes its hash, breaking the link to the next block. The tamper simulation in the Integrity tab proves this instantly.