Payy is a privacy-focused stablecoin payments infrastructure and privacy layer for ERC‑20 assets, positioned as “private by architecture” while retaining compatibility with familiar EVM tooling and user experiences.

The project describes itself as delivering private balances and transfers, URL‑based value transfer, selective auditability, and a non‑custodial card, with a live network on Ethereum and a broader roadmap emphasizing stablecoin‑native functionality and EVM compatibility. ^{[1] [2]}​

Overview

Headed by co-founder and CEO, Sid Gandhi, Payy’s stated purpose is to provide private payment rails and tooling for stablecoins and ERC‑20 tokens. The system is designed to hide balances and transfers at the protocol level using zero‑knowledge (ZK) circuits and a note‑based model, while also exposing a developer interface compatible with EVM ecosystems. Public materials emphasize a combination of private‑by‑default finance and selective auditability, intending to serve consumer wallets, enterprise transfers, payouts, and card‑based spending with privacy guarantees that can be programmatically opened to authorized reviewers. ^{[1] [2]}​

At a high level, Payy combines a privacy rollup architecture, a bridge to and from the public EVM, client‑side proof generation, and a sparse Merkle tree to authenticate both private commitments and spent states (nullifiers). The project’s documentation claims complete EVM opcode support and the availability of native ZK precompiles to facilitate private operations, while the public site lists products including a wallet (Payy Wallet), a URL‑based transfer mechanism (Payy Links), and a non‑custodial Visa card (Payy Card). ^{[1] [2] [3]}

History

Payy’s publicly reported milestones include product and network releases, funding, and partnerships:

• On October 10, 2024, Circle selected Payy for a USDC Grant Program cohort, signaling early engagement with stablecoin ecosystem stakeholders. ^[1]
• On August 6, 2025, Payy announced the Payy Card, described as a non‑custodial Visa card featuring balance and transaction privacy. ^[1]
• On February 4, 2026, the team published a blog post announcing Payy Network on Ethereum, followed by a February 19, 2026 notice stating the network was live on Ethereum. ^[1]
• On March 25, 2026, Payy announced a $6 million seed round led by FirstMark Capital. ^[1]
• On April 23, 2026, Payy reported a partnership with Rain to provide private settlement for Rain’s stablecoin card program. ^[1]
• On April 29, 2026, Payy disclosed a partnership with Toku to support private stablecoin payroll. ^[1]
• On May 8, 2026, Payy publicized the release of the @payy/client TypeScript SDK on npm, intended for building against the EVM privacy bridge with local signing and proof generation. ^[1]

These items are presented in Payy’s public announcements; as of the current date, they are not independently verified here beyond Payy’s own materials. ^[1]​

Technology and Architecture

Design Aims and Compatibility

The documentation characterizes Payy as privacy‑first, stablecoin‑native, and EVM compatible. Privacy is presented not as an optional add‑on but rather as a cross‑layer property embedded in transaction and storage semantics.

The platform emphasizes compatibility with existing EVM tooling, claiming support for every EVM opcode and presenting native ZK precompiles as a way to enable private functions without breaking familiar developer workflows. ^[2]​

Core Components

• Payy Network: Provides block production, a transaction pool, validator processes, and RPC services for running nodes and interacting with the system. ^[2]
• PrivacyBridge: Serves as the EVM boundary for moving assets into, within, and out of privacy pools, linking public EVM state to Payy’s private system through standardized circuits and a fixed public input ABI. ^[2]
• Privacy Layer: Implements native privacy pools, note‑based value, nullifiers (to prevent double‑spends), and a privacy rollup with ZK circuits for common operations. ^[2]
• Provers: Aggregate proofs produced client‑side and submit rollup state to Ethereum, forming the backbone of Payy’s off‑chain computation and on‑chain state updates. ^[2]
• Privacy Vault: Provides storage and interfaces for wallet‑compatible private data, local proof generation, and opt‑in data sharing. ^[2]
• Key Management System (KMS): Offers encrypted key recovery, scoped paths, sandboxed authorization scripts, and support for on‑chain recovery policies. ^[2]
• Payy Transactions: Encompasses protocol‑level transaction features including stealth addresses, batching, scheduled and recurring payments, sponsored gas, and concurrency handling. ^[2]
• Polylang: A TypeScript‑inspired domain‑specific language for writing provable computations and zero‑knowledge circuits deployed within the platform. ^[2]
• Payy Client SDK (@payy/client): A TypeScript SDK for interacting with the PrivacyBridge and local privacy signing and proof generation, including adapters for widely used EVM libraries. ^[2]

These components are presented as part of an integrated ZK rollup design aimed at stablecoin payments with usable developer interfaces. ^[2]​

Data Model and ZK Circuits

Payy uses a UTXO‑style “private notes” model rather than public account balances. Value is embedded into notes committed to a sparse Merkle tree, with nullifiers marking notes as spent without revealing linkages between transactions. The system implements key circuit families—mint, burn, transfer_send, and transfer_claim—enabling issuance, redemption, and two‑step transfers where a sender privately creates a note and a receiver later claims it.

This two‑step flow supports URL‑based payment claims (used for Payy Links/Cash Links) and recipient discretion over when to finalize receipt. ^[2]​

A notable design decision is the storage of both commitments and nullifiers in a single sparse Merkle tree structure (referred to as SMIRK), intended to authenticate both note existence and spent status within one authenticated data structure.

Client devices are emphasized as the locus of private key handling and proof construction, with aggregator provers combining and submitting proofs for inclusion in rollups. ^[2]​

Bridge ABI and Public Inputs

The PrivacyBridge employs a fixed‑shape public input ABI with 33 public inputs, standardizing how circuits interface across the EVM boundary. This decision is intended to stabilize developer integrations and reduce the complexity of on‑chain verification across evolving circuit logic. ^[2]​

Performance Characteristics and Rollup Flow

The documentation presents a ZK L2 rollup architecture designed for rapid, deterministic finality and high throughput. Materials cite deterministic finality of approximately 300 milliseconds and an initial throughput target around 10,000 transactions per second, with scaling potential up to 100,000 TPS. ^[2]​

Products and Services

Payy Wallet

Payy Wallet is presented as a stablecoin‑centric wallet and neobank experience layered on Payy Network. Public materials describe usage spanning over 100 countries and emphasize private balances and transfers within user interfaces that mirror conventional fintech apps. The specific footprint, licensing, or independent usage data are not detailed in the cited sources. ^[1]​

Payy Card

Payy Card is described as a private, non‑custodial Visa card integrated with Payy’s privacy features. Marketing claims present it as the only self‑custodial Visa card offering balance and transaction privacy; this statement appears as a project claim without third‑party corroboration in the cited materials. ^[1]​

Payy Links (Cash Links)

Payy Links—or Cash Links—enable URL‑based value transfer in which a sender transmits value by link and the recipient decides when to claim it. This capability builds on the two‑step transfer_send and transfer_claim circuit flow within the privacy layer, allowing a claim to be finalized only when the recipient executes the claim step. ^{[1] [2]}​

Private Payments and Enterprise Features

Beyond end‑user products, Payy positions itself as payment rails for enterprises and fintech integrators, including features such as confidential intra‑organization transfers, private vendor payments with selective auditor access, and private payouts. The target integrations listed include embedded wallets, neobanks, card programs, payroll processors, and autonomous agents. ^[1]​

Developer SDK

The @payy/client TypeScript SDK is presented as a developer toolkit for building against the EVM privacy bridge, enabling local privacy signing and proof generation. Integration paths include adapters for common EVM libraries, and documentation includes “Get Started” and compatibility guides intended to ease onboarding. ^[2]​

Use Cases and Adoption

Payy highlights several use cases consistent with its private and selective‑audit model:

• Embedding private wallets within consumer apps without exposing user chain management.
• Confidential treasury and intra‑organization movements with role‑based or authorized reviewer visibility.
• Vendor payments and payouts where commercial confidentiality is needed, with controlled data disclosure.
• URL‑based payouts and claims via Payy Links, enabling claim‑at‑will by recipients.
• Card‑based spending through Payy Card for private settlement of stablecoin‑denominated transactions.

These use cases and the target customers—such as enterprises, card programs, payroll providers, and neobanks—are presented by the project as intended market applications. ^[1]​

Partnerships and Funding

Payy lists a $6 million seed round led by FirstMark Capital and highlights collaborations with Circle (selection for a USDC Grant Program cohort), Rain (private settlement for a large stablecoin card program), and Toku (private payroll for stablecoins). The platform’s public materials position these as strategic relationships in payments, payroll, and stablecoin infrastructure. ^[1]​

Reception and Coverage

Payy’s site cites mentions in outlets including Yahoo Finance, Axios, The Block, CoinDesk, Nasdaq, Binance Square, and CoinMarketCap in connection with its funding and product announcements. Specific article links and independent evaluations are not enumerated within the sources used here. ^[1]​

Architecture Details

Privacy Notes, Nullifiers, and SMIRK

The platform’s privacy model centers on UTXO‑style notes representing value without exposing account balances. Each note’s lifecycle is bound to a nullifier that, when revealed, marks the note as spent without linking back to the sender. Payy reports using a single sparse Merkle tree (SMIRK) to hold both commitments and nullifiers, allowing authenticated proofs of existence and spent status. This arrangement is designed to reduce complexity in verifying state transitions while retaining privacy guarantees. ^[2]​

Transaction Semantics

Payy describes transaction features beyond basic private sends, including:

• Stealth addresses for recipient privacy.
• Batching to reduce overhead and group operations.
• Scheduled and recurring payments for automated disbursements.
• Sponsored gas (meta‑transactions) to abstract fees from end users.
• Concurrency primitives to coordinate state updates and avoid conflicts.

These features are presented as part of the Payy Transactions model and are integrated with the privacy circuits and rollup pipeline. ^[2]​

Bridge and EVM Interface

The PrivacyBridge links public EVM contracts and balances with Payy’s private system. The documentation states that it uses a fixed set of public inputs (33) to standardize verification and facilitate stable ABI expectations for developers. This decision, together with native ZK precompiles, is intended to make private operations feel familiar to EVM developers while maintaining privacy at the transaction and storage layers. ^[2]​