StarkWare has officially launched OffMarket, a zero-knowledge-based privacy service that lets users trade on Polymarket without publicly linking their positions to their existing wallets. Zero-knowledge proofs, the cryptographic technique behind the service, make it possible to verify information without revealing the underlying details. The tool, which operates on Starknet, became publicly available after a limited early release that began in August.

The service addresses a long-standing concern in prediction markets — platforms where users trade contracts tied to the outcomes of real-world events and prices reflect the odds implied by traders. Polymarket records all trades publicly on Polygon, making it possible for anyone to examine account positions, order sizes, and trading histories. This transparency has previously enabled blockchain analysts to identify high-profile traders, including a French bettor who wagered tens of millions of dollars on the outcome of the 2024 U.S. presidential election. More recently, Bloomberg reported detecting at least 34,000 trades flagged as potentially suspicious between August 2025 and June 2026.

How OffMarket Works

OffMarket routes user funds through Starknet's shared, open-source privacy pool — a design in which deposits from many users are commingled so that positions on the public exchange cannot be readily matched back to a specific wallet — which currently holds approximately $1.5 million across 17,000 deposits, according to L2BEAT data cited by StarkWare. Trades themselves are executed directly on Polymarket, meaning users interact with the same counterparties and market prices as everyone else. Deposit limits are set at $1,000 USDC per account for now, with plans to adjust the cap based on demand and usage; the pool's deposit figures, publicly tracked via L2BEAT, offer a running view of how widely the service is being used.

The company announced the public rollout on X:

OffMarket is the only way to trade prediction markets privately. It only takes a few seconds, with access to Polymarket liquidity while keeping your trades private. Stay OffMarket.

— StarkWare (@StarkWareLtd) October 14, 2026

A Non-Custodial Model With Guardrails

OffMarket operates entirely on a non-custodial basis — a structure in which a service never takes possession of users' funds or keys: users retain control of their private keys in their browsers, sit in the audited privacy pool, and Polymarket positions are held in contracts derived from user signatures. If the service ever goes offline, users can recover their wallets independently using those signatures. OpenZeppelin audited the pool contract in June without identifying critical or high-severity issues, and StarkWare formally verified it the following month.

Part of a Broader Privacy Push

The launch extends a wider privacy initiative by Starknet, which introduced its STRK20 privacy framework for shielding ERC20 balances in June and unveiled Shadow Accounts this week, a feature allowing users to interact with applications without linking activity to their main wallets. StarkWare co-founder Eli Ben-Sasson, a founding scientist of Zcash, framed the project as a continuation of his long-standing work on financial privacy.

That said, the privacy offered is not absolute. Markets, prices, and trades remain public on Polymarket, and observers can still attempt to identify traders through transaction size or timing — a limitation inherent to any privacy tool operating on top of a transparent blockchain. Usage of the pool is expected to grow to mitigate this.

Independence and Compliance Guardrails

OffMarket is not an official Polymarket product and holds no special access to the platform, though it participates in the exchange's verified builder program, which Polymarket could disable — meaning the service's ability to operate depends in part on that status. The service enforces Polymarket's geographic restrictions, including the ban on U.S. users — a restriction dating to Polymarket's 2022 settlement with the U.S. Commodity Futures Trading Commission over an unregistered event-markets platform — and routes compliance through Financial Privacy Inc., an independent firm holding the master viewing key in a secure enclave under a multisignature arrangement. Deposits are screened against sanctions lists, and any disclosure of transaction data to courts or regulators requires verified legal authority.

This article originally appeared on Metaverse Post.