zk Privacy Solution Comparison

zkBob | zk.money | Railgun | Tornado.cash |

How does zkBob compare to other privacy protocols?

zkBob provides everyday privacy to everyday users. Limits, compliant wallet checks, and other security features ensure that zkBob is a safe place for honest users to discreetly transfer stable value.
Different privacy solutions offer different tradeoffs for users seeking anonymity on-chain. Below are some features that set zkBob apart.
Secret Network
zk.Money (sunset & no longer active)
Tornado.cash (pre-ban)
Stable fees
$0.10/tx on Polygon $0.50/tx on Optimism
Optional KYC
users can submit KYC to increase deposit limits.
No KYC option for individuals
No KYC option for individuals
No additional wallet required
standalone transfers and withdrawals from app
requires wallet
requires wallet
requires wallet
requires wallet
No native tokens required
BOB stablecoin used for all interactions
required for shielding
SCRT required for fees
required for withdrawal and deposit
required for withdrawal/deposit
read more
Deposit limits (non-KYC)
< 10K BOB per address in 24 hours, 300K total protocol per 24 hours
Tiered deposit limits (KYC'd)
< 20K BOB per address in 24 hours.
Current withdrawal limits
< 300K per day for the total protocol
Current pool size limits
2M BOB Polygon 10M BOB Optimism
TRM compliance integration
Risk management and illicit funds detection
Cloud API
Beta Gated implementation
A big differentiator between the protocols is zkBob’s use of the BOB stable token for transactions and fees. Tx fees do not fluctuate for users (hard coded to $0.10 per tx on Polygon/ $0.50 per tx on Optimism). If the actual tx cost is less, the extra amount is collected and dedicated to protocol and user support. In rare cases when it costs more, txs are divided and processed in several transactions.
The BOB stable token has additional utility including the ability to introduce compounding and lost/expired token redistribution. These features on the roadmap will provide future incentives for zkBob users.
Multitransfer is another unique zkBob feature, allowing users to transfer to multiple zk addresses with a single transaction. This is especially useful for employers sending salary payments to many employees. Rather than create proofs and pay fees for each tx, these can be sent in bulk, saving time and overhead costs.
Additional zkBob roadmap items include multi-chain deployment, decentralized relayer infrastructure, and fast client state sync also set it apart from competitors in the space.
In the table below we explore some technical and operational differences between zkBob, zk.money and Tornado.cash (pre-ban).

Operational Comparison Table

Note comparisons were made to show varying technology and zk tech. As zk.money and tornado.cash are no longer in active operation (sunset or banned), zkBob is currently the primary solution for optional privacy.
zk.money (now sunset)
Tornado.cash (pre-ban)
Deployment Chain
Aztec Network Rollup
Ethereum/Gnosis Chain
Verification time
~3 ms
~ 6ms
~3 ms
Prover algorithm RAM requirements
Trusted setup
Per circuit
Per circuit
Deposit gas size
Arbitrary Deposits/Transfers/Withdrawals?
Regular TC
TC Nova
Gas fee token(s)
-> BOB deposits & withdrawals (no native token required)
-> ETH deposits & withdrawals
-> ETH deposits & withdrawals
Transfer token(s)
BOB stable token
zkETH / zkDAI / zkrenBTC
Transaction times
< 1 minute, Polygon infra
Variable (4hours to < 5 min) based on desired fee
< 1 minute, Nova on Gnosis Chain infra
XP Auctions on roadmap
TORN governance token
Geo restrictions
Multi-chain deployment
On roadmap
(prior roadmap)
Decentralized relayers
On roadmap
(Multi-rollup infra on Roadmap)
Fast client-state sync
On roadmap