Crailo
Scam free resale, never been cooler
The problem Crailo solves
🛡️ The Problem Crailo Solves
Traditional Resale Marketplaces: A Breeding Ground for Scams
Most peer-to-peer (P2P) resale platforms like OLX, Craigslist, and Facebook Marketplace suffer from a lack of trust and protection:
- ❌ No escrow system – buyers must blindly trust sellers and send payment upfront.
- ❌ Fake listings – sellers often use misleading images or descriptions to scam buyers.
- ❌ No dispute resolution – once a transaction goes wrong, recovery is nearly impossible.
- ❌ No accountability – there are few penalties for bad actors.
These issues lead to rampant fraud, no buyer protection, and loss of money and trust.
✅ How Crailo Makes Resale Safer & Smarter
Crailo brings trustless safety and accountability to resale marketplaces using smart contracts, staking mechanisms, and a validator network:
🔐 Escrow-Backed Transactions
Buyers deposit the full amount into a smart contract, not directly to the seller — ensuring payment is only released when the item is verified.
🧾 Seller Staking for Honesty
Sellers must stake 10% of the product price, which is forfeited if the listing is fraudulent. This discourages scams up front.
👨⚖️ Decentralized Dispute Resolution
If a buyer raises a dispute, validators vote on the authenticity of the product. The decision is on-chain, fair, and tamper-proof.
💸 Slashing & Incentives
- Buyers who back out post-validation get penalized.
- Fraudulent sellers lose their entire stake.
- Validators earn ERC-20 rewards, aligning their incentives with platform integrity.
📈 Optional Reputation & Staking Pools
Repeat sellers can build reputation via a staking pool, helping buyers trust verified sellers more easily.
🎯 Use Cases
- 🔄 Second-hand electronics (phones, laptops, etc.)
- 👟 Hypewear & fashion resale (e.g., sneakers, limited drops)
- 🪑 Furniture or appliances with high transaction values
- 📦 B2B liquidation resale where both parties seek added protection
Challenges we ran into
🧱 Challenges I Ran Into
Building Crailo wasn’t just about writing smart contracts — it required solving real-world edge cases in decentralized P2P commerce. Here are a few key hurdles I faced:
⚠️ 1. Designing Fair & Tamper-Proof Dispute Resolution
Problem:
Building a validator-based system that’s fair, resistant to Sybil attacks, and aligned with user incentives was challenging. Simply allowing anyone to vote could lead to collusion or manipulation.
Solution:
We introduced a staking requirement for validators — only users with a minimum stake could participate in voting. This disincentivizes bad actors and aligns validator interests with the platform’s integrity. We also implemented slashing for validators who consistently vote against the consensus.
⚠️ 2. Preventing Front-Running & Double Listings
Problem:
Onchain marketplaces are prone to front-running (bots buying before humans) or repeated listing of the same fake item under different addresses.
Solution:
We added listing fingerprints (hashes) and timestamp locks to prevent immediate relisting. Each product listing is associated with a unique hash generated from item details + seller wallet + timestamp, making duplicates detectable.
⚠️ 3. Ensuring Gas-Efficient Escrow Logic
Problem:
Initial escrow logic involved multiple contract calls (listing, buying, staking, dispute trigger), which resulted in high gas usage.
Solution:
We modularized the contract logic but optimized storage and reduced state updates using minimal proxies and struct packing. We also merged buyer and seller interactions into batched transactions where possible.
⚠️ 4. UX for Validator Voting Flow
Problem:
Validator voting required a balance between decentralization and ease-of-use. We noticed confusion among test users on how/when they could vote.
Solution:
We added real-time UI prompts and status badges using frontend state management (e.g., Zustand or Redux), letting validators know when they’re eligible to vote and what the product images look like side-by-side.
Every challenge we solved made Crailo more secure, robust, and user-friendly — bringing us closer to a safer onchain resale economy.
Tracks Applied (2)
Best Use of MongoDB Atlas
Major League Hacking
Build for Core Connect Global Buildathon
Core DAO
Technologies used
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