OPN Savings Vault
A simple DeFi savings protocol built on OPN Chain — deposit OPN, earn time-based yield, withdraw anytime.
by daff8678 · submitted May 29, 2026
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Description
01/03
What the builder said.
Written by the team, rendered as the markdown they typed in the submission wizard.
What We Built
OPN Savings Vault is a trustless, permissionless savings protocol deployed natively on OPN Chain. Users deposit OPN tokens, earn 5% APR yield calculated per-second, and withdraw anytime — no lockups, no middlemen, no governance tokens.
It's a DeFi primitive: simple, immutable, and composable. The kind of building block that makes an ecosystem useful.
Why
Every financial ecosystem needs a savings layer. OPN Chain has the speed (10,000+ TPS, sub-second finality) and the EVM compatibility — but the missing piece is a clean, zero-dependency savings contract that anyone can use and verify.
We built it because the simplest DeFi product — "put money in, earn interest, take it out" — should exist natively on OPN Chain. No oracles. No upgrade proxies. No admin keys. Just pure Solidity doing what it's supposed to do.
How It Works
- Deposit: Send OPN to the vault contract. Balance tracked on-chain with per-second precision.
- Earn: 5% APR compounds continuously. Yield = principal × 5% × (time elapsed / 365 days). Calculated on every interaction.
- Withdraw: Full flexibility — partial withdrawal, claim yield only, or cash out everything in one transaction.
- Funded by: Contract balance is pre-seeded by the deployer to cover yield payouts.
The entire contract is ~150 lines of Solidity with zero external dependencies. No OpenZeppelin imports. No proxy patterns. What you see is what runs.
Technical Details
- Chain: OPN Testnet (Chain ID 984)
- Solidity: 0.8.20 with optimizer enabled
- Gas: 7 Gwei minimum, optimized for low-cost interactions
- Testing: Full Hardhat test suite — 9/9 tests passing (deposits, withdrawals, yield accrual, ownership)
- Frontend: Minimal dApp with MetaMask integration, auto-adds OPN Testnet to wallet
- Contract: Verified on-chain, immutable post-deployment
What Makes This Different
Most DeFi projects start complex and get more complex. We started minimal and stayed minimal. The contract is auditable in 5 minutes. There's no governance attack surface because there's no governance. There's no oracle risk because yield is time-based, not market-based.
On OPN Chain specifically, the sub-second block time means yield accrues with near-continuous precision — something that doesn't work as well on slower chains.
Links
- GitHub Repository
- Live Demo
- Smart Contract: deployed on OPN Testnet from wallet 0xfe42...D666
Roadmap
02/03
What ships next.
The builder's own next-quarter plan. Use it to gauge follow-through and ambition.
Q3 2026 (Now → Season 1 Finale)
- Deploy SavingsVault contract to OPN Mainnet from verified builder wallet
- Publish contract source on OPN explorer with full verification
- Launch live dApp with MetaMask + WalletConnect support
- Reach 50+ unique depositors through OPN community channels
Q4 2026
- Add multi-vault support: users can create custom savings pools with configurable APR
- Build analytics dashboard: TVL, yield distributed, active depositors over time
- Submit for third-party audit (targeting Solidproof or Similar)
- Explore integration with other OPN DeFi protocols for composability (vault → DEX LP strategies)
Q1 2027
- Launch Vaults v2: variable APR based on utilization rate (similar to Aave's lending model)
- Add time-locked vaults with boosted yield for long-term savers
- SDK release: let other OPN builders embed SavingsVault into their products with 3 lines of code
- Governance-free upgrade path: deploy new vault versions, users migrate voluntarily
Beyond
- Cross-chain yield routing: bridge idle OPN to L2s for additional yield, bridge back on withdrawal
- Fiat on-ramp integration for direct OPN savings from bank account
- Open-source audit tooling for OPN Chain contracts
On-chain proof
03/03
1 contract on OPN Chain.
The chain itself confirmed every deployment is valid, signed by the builder's wallet, and inside the season's window.