Ethereum Foundation Kohaku SDK Brings Privacy to Wallets
— By Tony Rabbit in news
The Ethereum Foundation released the Kohaku SDK on May 25, 2026, an open-source toolkit that lets any Ethereum wallet integrate Railgun, Tornado Cash and Privacy Pools directly at the wallet layer. v0.0.1-alpha.21 ships with operational EIP-4337 mempool relaying through the Railgun integration. Production wallets including Ambire and a browser extension built with breadcoop are preparing integrations. Vitalik Buterin endorsed the launch in a May 26 X post.
The Ethereum Foundation released the Kohaku SDK on May 25, 2026, an open-source toolkit that lets any Ethereum wallet integrate privacy protocols like Railgun, Tornado Cash and Privacy Pools directly at the wallet layer. The release is the first practical milestone for the Kohaku Initiative, the Foundation's privacy-by-default roadmap announced at Devcon 2025. The v0.0.1-alpha.21 release ships with operational EIP-4337 mempool relaying for private transactions through the Railgun integration, with Tornado Cash and Privacy Pools wrappers in active development.
Vitalik Buterin commented on the launch in a May 26 X post, urging the ecosystem to push beyond privacy narratives into shipping production wallet integrations. Production wallets including Ambire are preparing implementations, and a browser-extension experimental wallet built with breadcoop is also in progress.
What Kohaku gives wallet developers
Kohaku's design goal is making privacy integration as simple as plugging a library into a wallet build. Today, if a wallet wants to support Railgun shielded pools, the team has to integrate the Railgun SDK, run relayer infrastructure, handle 4337-compatible bundler routing and rebuild the privacy UX from scratch. Kohaku consolidates all of that into a single modular SDK with three layers:
- Protocol adapters: Plug-in modules for each shielded pool (Railgun first, Tornado Cash and Privacy Pools next).
- Relaying infrastructure: Operational EIP-4337 mempool relaying that handles the 4337 UserOperation flow for private transactions without exposing wallet identity.
- Wallet hooks: Standard hooks any wallet (Ambire, MetaMask, Frame, breadcoop's experimental extension) can call to surface shielded deposit, transfer and withdrawal as native flows.
The roadmap also includes zero-knowledge recovery and decentralized transaction handling, both of which sit at the wallet-level rather than the protocol-level. The recovery design lets users restore wallet access without ever exposing the underlying private keys, while decentralized transaction handling routes signed transactions through a network of relayers rather than a single point.
Why the Foundation is pushing this now
Ethereum privacy has been a recurring narrative for years without a corresponding leap in actual user-facing privacy. Adoption of standalone privacy protocols like Tornado Cash compressed after sanctions enforcement, and Railgun has remained a niche power-user tool. The Foundation's bet with Kohaku is that privacy needs to be built into the wallet by default, not bolted on as an opt-in flow with a separate UI.
The timing also reflects a broader ecosystem rotation toward privacy infrastructure. Monero's FCMP++ launch was the biggest privacy upgrade for that chain to date, and Zcash's ZEC rally reflected renewed market interest in privacy coins. Ethereum's response is structurally different. Rather than launching a privacy chain or coin, the Foundation is making it cheaper for every Ethereum wallet to ship privacy at the application layer.
Vitalik's nudge
Vitalik Buterin's May 26 X post replied to a thread on Kohaku's wallet-level privacy work with an explicit push for the ecosystem to "go beyond privacy narratives" and ship the actual user experience. The framing is important. The Foundation has historically refrained from picking winners among privacy protocols, but the Kohaku release effectively endorses a shielded-pool-plus-wallet-integration architecture as the canonical path forward.
For wallet developers, the message is that adopting Kohaku is now the cheapest way to add credible privacy support. For privacy protocols (Railgun, Tornado Cash forks, Privacy Pools), the message is that the integration surface area has been standardised: ship a Kohaku adapter and you get distribution into any wallet that adopts the SDK.
Kohaku in numbers
- Release date: May 25, 2026
- Version tag: v0.0.1-alpha.21
- Primary integration: Railgun (live)
- Next integrations: Tornado Cash, Privacy Pools (in development)
- Relay standard: EIP-4337 mempool relaying
- Wallet partners (active): Ambire (production wallet), breadcoop experimental browser extension
- Open source: Yes, full repo published by Ethereum Foundation
- Vitalik public statement: May 26, 2026 (X post)
Impact on the Ethereum privacy stack
Kohaku's release is the first piece of Foundation infrastructure that meaningfully lowers the cost of adding privacy to a mainstream Ethereum wallet. If even two or three top-10 wallets adopt the SDK, the addressable pool of users who can transact privately on Ethereum jumps by an order of magnitude. That changes the calculus for compliance-conscious users who want shielded transfers without having to download a separate app.
The implications for downstream products are also large. Layer 2 rollups that want to differentiate on privacy can integrate Kohaku at the wallet layer rather than rebuilding their own. Onchain agent platforms like Coinbase Agentic.Market can use Kohaku to shield agent-to-agent payment flows. The pattern is the same: Kohaku turns privacy from a separate product into a wallet feature.
Things to know
Where to track Kohaku
The primary source is the Ethereum Foundation Kohaku Initiative GitHub repository, which hosts the SDK source, release notes and integration guides. DEXTools tracks pool activity for the underlying privacy tokens (RAIL on Railgun, ZK pool tokens on Privacy Pools), which is the cleanest onchain proxy for how much volume is routing through Kohaku-integrated wallets.
Between now and the next alpha release, watch for Ambire and breadcoop integration milestones. Both teams have publicly committed to shipping Kohaku-powered wallet flows, and their first production releases will be the test case for whether wallet-layer privacy actually moves user behaviour.
Frequently asked questions
What is the Kohaku SDK?
Kohaku is an open-source SDK from the Ethereum Foundation that lets wallets integrate privacy protocols like Railgun, Tornado Cash and Privacy Pools directly at the wallet layer. It ships with operational EIP-4337 mempool relaying for private transactions.
When did Kohaku launch?
The Ethereum Foundation released Kohaku v0.0.1-alpha.21 on May 25, 2026, with Vitalik Buterin publicly endorsing the launch in a May 26 X post.
Which wallets are integrating Kohaku?
Ambire is preparing a production wallet integration, and an experimental browser extension developed in collaboration with breadcoop is in progress. Other production wallets are expected to follow as the SDK stabilises.
Which privacy protocols does Kohaku support?
Railgun integration is live with operational EIP-4337 relaying. Tornado Cash and Privacy Pools adapters are in active development under the modular SDK architecture.
Where can I follow Kohaku updates?
The Ethereum Foundation Kohaku Initiative repository hosts source and release notes. DEXTools tracks underlying privacy protocol token activity, the cleanest onchain proxy for adoption.