Summer.fi (previously Oasis.app) is a platform for decentralized finance (DeFi). It can be used to borrow stablecoins against users’ favorite cryptocurrencies, increase exposure against them using Multiply, or Earn a competitive yield. ^[1]​^[2]​

Overview

Summer.fi offers users three main products and advanced automation features. Stop-Loss helps prevent liquidation and potential losses. Auto-Buy, Auto-Sell, and constant multiple features aim to optimize the performance of a user's Vault. ^[3]​

In August 2023, Summer.fi raised $6 million while closing its Series A funding round. Having received these funds through a mix of fiat and crypto, and led by Libertus Capital, this funding was dedicated to developing the product, bringing on more people, and expanding offerings. The funding round also included other angel investors in the crypto space like Road Capital, Mariano Conti, former Head of Smart Contracts at MakerDAO; Patricio Worthalter, founder of POAP; Cyrus Younessi, former Head of Risk at MakerDAO; Sergej Kunz and Anton Bukov, Co-founders of 1inch and Will Price. ^[11]​

“It's been an incredible journey so far. We're proving our vision of becoming the most trusted place in DeFi to deploy and manage capital. This latest funding allows Oasis.app to scale the features our community will be looking for next. As a team we are humbled to be working with such incredible investors who are already taking us forward with their experience of this space.

This is a big-time for DeFi as users are not only seeing the potential but finding the tech to access it. It's still early days for DeFi and we are excited to be driving the next phase of adoption.” - Chris Bradbury, Oasis.app CEO^[11]

Products

Multiply

Summer.fi Multiply allows users to utilize borrowed tokens to buy more collateral within the platform, enabling increased or decreased exposure to a single asset without multiple transactions. Users can deposit collateral to borrow debt tokens such as DAI or USDC to purchase more collateral, multiplying their asset exposure in a single transaction. Supported tokens like ETH, wBTC, stETH, and rETH can be used. Summer.fi Multiply employs flash loans and liquidity sourcing from 1inch DEX aggregator to ensure cost-effective execution and optimal prices for swaps. ^[4]​

Borrow

Summer.fi Borrow allows users to lend and borrow funds through an intuitive user interface. Key benefits include access to extra liquidity by borrowing DAI, a stablecoin useful for trading, spending, or saving. It offers various collateral types, rates, and ratios suitable for different risk profiles. Additionally, the platform features flexible repayment options with no fixed schedules, minimum payments, or credit history requirements, allowing users to repay at their own pace as long as their Vault remains properly collateralized. ^[5]​

Earn

Summer.fi Earn is a full self-custody solution for entering and exiting yield positions so users will always stay in control of their funds. ^[6]​

Increase the yield received from StETH. Upon opening a position, a flash loan for Dai is taken from Maker and deposited into the Aave Protocol. Then ETH is borrowed until it reaches the desired multiple level. Next, the loaned ETH and the user’s initial deposit are exchanged to StETH via 1Inch. The return comes first from the ETH staking yield provided by StETH. That yield is multiplied by increasing exposure to StETH by borrowing ETH. ^[6]​

RAYS

Introduced on June 20, 2024, $RAYS is the points system within Summer.fi. The program rewards users for using the platform. ^[7]​

It's our reward to the community and the first step of the broader roadmap with our "Summer.fi Earn Protocol" in early 2025. - the team tweeted^[7]

The Summer.fi $RAYS Campaign is in preparation for the launch of the Summer.fi Earn Protocol, coming in early 2025. ^[8]​

The accrual of $RAYS allows users to express any market view and risk preference whilst incentivizing the usage of Summer.fi tools and features. ^[10]​

Team

• Chris Bradbury - CEO
• Soren - Director
• Andrei - CTO
• Joe - CFO
• Maria - Marketing Lead
• Javier - Community Manager^[9]

Lazy Summer Protocol Exploit and Postmortem

On July 6, 2026, the Lazy Summer Protocol suffered an exploit that resulted in the loss of approximately $6.04 million across two USDC vaults. ^[12]

The attack targeted the protocol’s vault accounting mechanism rather than compromised private keys or administrative privileges. According to Summer.fi’s postmortem, the attacker manipulated the vault’s Net Asset Value (NAV) by donating severely overvalued Silo “Varlamore USDC Growth” vault tokens into an Ark that had been disabled for new deposits but was still included in the vault’s NAV calculations.

This artificially inflated the vault’s share price, allowing the attacker to redeem shares for significantly more USDC than the deposited assets were actually worth. ^[12]

The exploit was executed in a single atomic transaction using flash loans, although the attacker had reportedly spent more than three months preparing by accumulating the mispriced Silo vault tokens through multiple wallets.

Once the vault’s NAV was inflated, the attacker withdrew approximately 400,000 from the Higher Risk USDC Vault before swapping part of the stolen funds and routing them through Tornado Cash. Summer.fi emphasized that the exploit was not caused by a flaw in the vault contracts themselves, but by an incomplete offboarding process that left a capped, impaired Ark active within the protocol’s NAV calculations.

Following the exploit, the protocol paused all vaults across Ethereum, Base, Arbitrum, Sonic, and HyperEVM, while the Guardian multisig set vault deposit caps to zero to prevent additional attacks. Summer.fi stated that the Guardian Module, which can pause vaults and adjust deposit caps but cannot move user funds, functioned as intended during the incident. The protocol also began conducting a full on-chain reconciliation of affected user balances and said governance would determine the process for restoring the remaining assets and reopening unaffected vaults.

In its conclusion, Summer.fi described the exploit as a highly sophisticated, long-planned attack and announced that governance would evaluate additional security measures, Ark offboarding procedures, and future protocol upgrades before normal operations resume. ^[12]