Software and research for self‑custodial money.

Move money. Hold nothing.

We build and publish Peanut, a payments app.

What we build Research

The key stays with the user.

Created with device biometrics and held by the phone's secure hardware. Squirrel Labs never receives it.

The signature authorises.

Each payment from the wallet is an ERC-4337 user operation, signed on the device by the passkey.

III

The ledger settles.

Funds move on Arbitrum into the user's own smart account.

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What we build

ProductP-1

Peanut

peanut.meiOS · Android

Stablecoins in, local money out, for example through PIX in Brazil or bank transfer.

Product · open sourceP-2

Peanut Split

peanutsplit.comAGPL-3.0-or-later

A shared-expense app.

Protocol · open sourceP-3

Peanut protocol

Smart contractsPayment links

Contracts for payment links: claimable links that carry value until the recipient claims them.

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Research

Writing and talks by Konrad Urban, co-founder.

Areas: account abstraction (ERC-4337), passkey and WebAuthn key custody, stablecoin settlement and local rails, payment-link cryptography, zero-knowledge proofs, smart-contract security.

02.1 · Writing

Essays

Published on kkonrad.substack.com.

More writing

No.TitlePublished

W-01I modeled wrench attacks. Privacy makes them worse.Feb 2026 W-02Who wins what as stablecoins slash costAug 2025 W-03Wen p2p electronic cash system?Jan 2025 W-04What happens when you buy coffee? Crypto vs cardDec 2024 W-05Towards Link-Based Transfer AbstractionMay 2024 W-06Can we sidestep onchain identity?Jul 2023

02.2 · Talks

Talks

All talks

No.TitleVenue

T-01When Help Hurts: Why a Friendly Government is a Threat to CryptoProtocol Berg v2 · 2025 T-02Wen p2p Electronic Cash System?Devcon 7 · 2024 T-03Chain abstraction? But I want to know where my tokens areDevcon 7 · 2024 T-04How can wallets deal with the multichain nightmare?Wallet Unconference · 2023 T-05Please stop obsessing about blockchain!ETHDenver 2023 · The Next Billion Summit

02.3 · Third-party reading · not our work

Papers we build on

From peer-to-peer cash to stablecoin payment rails.

No.TitleAuthors · venue

P-01Bitcoin: A Peer-to-Peer Electronic Cash SystemNakamoto · 2008 P-02Arbitrum: Scalable, private smart contractsKalodner, Goldfeder, Chen, Weinberg, Felten · USENIX Security 2018 P-03SoK: A Classification Framework for Stablecoin DesignsMoin, Sekniqi, Sirer · FC 2020 P-04ERC-4337: Account Abstraction Using Alt MempoolButerin, Weiss et al. · Ethereum standard, 2021 P-05The State of Passkeys: Studying the Adoption and Security of Passkeys on the WebJannett, Mayer, Westers, Mladenov, Mainka, Schwenk · USENIX Security 2026 P-06Competing Rails for Cross-Border Payments: Banks, Fintechs, and StablecoinsDu, Huang, Scharfstein · BIS Working Paper 1385, 2026

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Open source

RepositoryWhat it isLicence · status

Peanut Split Squirrel Labs is the sole upstream maintainer and pays the cost of running it. Code AGPL-3.0-or-later
Docs CC-BY-4.0
Maintained Repository →

Peanut protocol The payment-link contracts. GPL-3.0
Maintained Repository →

squirrel A zero-knowledge, decentralised payment-link experiment from 2022. The research line behind the payment-link contracts. Research
Archived, private

Issues and fixes are welcome on GitHub.

github.com/peanutprotocol

Custody is a promise. Self‑custody is a proof.
Squirrel Labs

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Principles

Principle I

Non-custodial

Keys are made on the user's device. Our software has nothing to hold.

Principle II

Open source

Anyone can read, audit, fork and run the code we publish.

Principle III

Security

Report issues to us privately before publishing them. See 05.

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Security & disclosure

More than $20,000 paid to security researchers since Peanut started.

Please give us the chance to fix an issue before you publish it. That figure is history, not a rate card.

Scope: Peanut app and website, Peanut API, the smart contracts behind Peanut accounts
Report to: Peanut support chat. Start at peanut.me/en/help/security-disclosure
Include: What you found, where, and how to reproduce it

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Company & compliance

Squirrel Labs is not a bank.

We are a software developer. We are not a money transmitter or a licensed financial institution, and we hold no financial licences.

Entity record

Name: Squirrel Labs Ltd, registered in England and Wales, company no. 14558823
Address: Office One, 1 Coldbath Square, London, EC1R 5HL, England
Contact: support@peanut.me

No custody

We never hold user funds or user keys.

Licensed partners

Licensed partners run fiat on-ramps, off-ramps and card issuing.