The Ethereum ecosystem continues to evolve with standards that enhance composability and flexibility in decentralized finance (DeFi). Among the most impactful developments is ERC-4626, which standardized yield-bearing token vaults. Now, ERC-7540 builds upon this foundation by introducing asynchronous deposit and redemption capabilities—unlocking new possibilities for real-world asset integration, cross-chain protocols, and complex financial instruments.
This article explores ERC-7540 in depth, detailing how it extends ERC-4626 with asynchronous request flows, why this matters for modern DeFi applications, and what developers and users should know about its design, implementation, and security implications.
What Is ERC-7540?
ERC-7540 is an Ethereum standard that introduces asynchronous request flows to ERC-4626 tokenized vaults. While ERC-4626 enables atomic deposits and withdrawals, it falls short when dealing with systems requiring time delays or off-chain processing—such as liquid staking, insurance modules, or undercollateralized lending.
ERC-7540 solves this by allowing users to submit a request to deposit or redeem assets, which enters a Pending state. Once processed by the vault, the request becomes Claimable, and the user must then explicitly claim their shares or assets using existing ERC-4626 functions like deposit or redeem.
This two-step process ensures compatibility while enabling asynchronous operations critical for advanced use cases.
Why Asynchronous Vaults Matter
Traditional ERC-4626 vaults assume immediate execution: you deposit assets and instantly receive shares. But many real-world scenarios require delays:
- Liquid staking: Unstaking ETH may take days.
- Cross-chain transfers: Bridging assets involves confirmation times.
- Credit risk assessment: Lending protocols may need time to evaluate borrowers.
- Real-world assets (RWA): Physical asset valuations aren’t instantaneous.
In these contexts, forcing synchronous behavior limits functionality or risks slippage and failed transactions.
ERC-7540 addresses this by decoupling request submission from fulfillment. Users lock assets or shares upfront, but final conversion happens later—preserving capital efficiency without sacrificing user control.
Core Concepts and Request Lifecycle
Understanding the lifecycle of a request is key to working with ERC-7540-compliant vaults.
The Three States of a Request
- Pending
After callingrequestDepositorrequestRedeem, the request enters the Pending state. Assets or shares are transferred to the vault, but no output tokens are issued yet. - Claimable
The vault processes the request (e.g., after a delay or external validation). It becomes eligible for claiming. No automatic payouts occur—users must actively claim. - Claimed
The user callsdeposit,mint,withdraw, orredeemto finalize the transaction and receive their tokens.
🔁 Important: Requests cannot skip the Claimable state. Even if fulfilled immediately, users must call a claim function. This prevents unexpected token pushes and simplifies integration logic.
Key Methods and Events
ERC-7540 adds several new methods and events to support asynchronous operations while maintaining backward compatibility with ERC-4626.
New Request Methods
requestDeposit(assets, controller, owner)
Initiates a deposit request. Transfers assets from owner to the vault and returns a requestId. The controller manages the claim process.
requestRedeem(shares, controller, owner)
Submits a redemption request. Locks or burns shares and returns a requestId. The controller can later claim the underlying assets.
View Functions
pendingDepositRequest(requestId, controller)→ Returns amount of assets awaiting processing.claimableDepositRequest(requestId, controller)→ Returns amount ready to be claimed.- Similar functions exist for redemption (
pendingRedeemRequest,claimableRedeemRequest).
Operator Management
isOperator(controller, operator)→ Checks if an address can act on behalf of a controller.setOperator(operator, approved)→ Grants or revokes operator status.
Overloaded Claim Functions
To support delegation, ERC-7540 overloads standard ERC-4626 methods:
function deposit(uint256 assets, address receiver, address controller)
function mint(uint256 shares, address receiver, address controller)These allow operators to claim on behalf of controllers, enhancing composability with smart wallets and DeFi aggregators.
Critical Events
DepositRequest(controller, owner, requestId, sender, assets)
Emitted when a deposit request is submitted.RedeemRequest(controller, owner, requestId, sender, shares)
Emitted on redemption request.OperatorSet(controller, operator, approved)
Logs changes in operator permissions.
Design Rationale Behind Key Decisions
Several architectural choices in ERC-7540 reflect deep consideration of usability, security, and extensibility.
Why No Claim-by-ID Function?
Although requests have IDs (requestId), there's no direct claimById() method. This keeps the interface lean and avoids forcing NFT-like complexity (e.g., ERC-721) onto all implementations.
Instead, claim functions use (requestId + controller) as a composite key. This allows flexibility—developers can build NFT-wrapped claims externally if needed.
Symmetry: Only requestDeposit and requestRedeem
Unlike ERC-4626’s symmetry between deposit/withdraw and mint/redeem, ERC-7540 only supports:
requestDeposit(based on asset amount)requestRedeem(based on share amount)
Why? Because asynchronous flows require certainty at submission time. You can’t reliably mint shares without knowing the exact asset amount that will be deposited later.
Similarly, withdrawing a specific asset amount asynchronously would require locking variable shares—too risky due to price fluctuations.
No Request Cancellation Built-In
There is no standardized way to cancel a pending request. This is intentional:
- Some vaults may not support cancellations (e.g., irreversible off-chain processes).
- Cancellation logic could be synchronous or asynchronous—adding complexity.
A future EIP may standardize cancellation patterns without bloating ERC-7540.
Security Considerations
Asynchronous logic increases surface area for potential issues.
Risks to Users
- Stuck funds: If a vault never marks a request as claimable, funds remain locked.
- Exchange rate uncertainty: The rate at claim time may differ significantly from submission.
- Operator trust: Operators can claim on your behalf—only approve trusted addresses.
Best Practices for Developers
- Implement clear documentation of fulfillment timelines.
- Add circuit breakers or admin controls (if governance-backed) for emergency handling.
- Use access control rigorously—especially around operator privileges.
- Test edge cases: reentrancy during claim, overflow in state tracking, etc.
Backward Compatibility
ERC-7540 is fully backward compatible with ERC-4626:
- Existing integrations continue working.
- Vaults can choose to implement async flows partially (deposit-only or redeem-only).
The standard uses
supportsInterface(ERC-165) to signal capabilities:0xce3bbe50→ supports async deposits0x620ee8e4→ supports async redemptions0xe3bc4e65→ general ERC-7540 support
Integrators can query these interfaces to adapt behavior dynamically.
Frequently Asked Questions (FAQ)
Q: Can I combine synchronous and asynchronous flows in one vault?
A: Yes. A vault can support synchronous deposits and async redemptions (or vice versa). For example, liquid staking tokens often allow instant deposits but require unstaking delays.
Q: How do I know when my request is claimable?
A: There’s no event for the Pending → Claimable transition. Frontends should poll claimableDepositRequest() or use off-chain notifications (e.g., webhooks).
Q: Are pending requests fungible?
A: Not inherently. While requests with the same requestId are fungible among controllers, pending claims themselves aren’t transferable unless wrapped in another token standard (like ERC-1155).
Q: Why do preview functions revert?
A: Functions like previewDeposit() revert in async vaults because the exchange rate isn't known at request time. This avoids misleading estimates and simplifies integrations.
Q: Can I use meta-transactions or account abstraction with ERC-7540?
A: Absolutely. The two-step flow works well with relayers and smart accounts. Routers can even bundle request + claim in one transaction if the vault allows immediate claiming.
👉 See how leading DeFi platforms use modular vault designs for seamless cross-chain yield aggregation.
Final Thoughts
ERC-7540 represents a significant evolution in DeFi infrastructure. By enabling asynchronous operations within the familiar ERC-4626 framework, it opens doors for:
- Real-world asset tokenization
- Cross-chain liquidity layering
- Delayed-risk assessment protocols
- Insurance and underwriting mechanisms
Its thoughtful design balances flexibility with security, avoiding over-engineering while empowering builders to innovate at higher layers.
For developers building next-generation vaults—or protocols integrating with them—understanding ERC-7540 is essential.
Whether you're exploring liquid staking, RWA-backed tokens, or decentralized lending pools with approval workflows, ERC-7540 provides the foundation for robust, scalable solutions in an increasingly asynchronous world.