Railgun
A non-custodial set of smart contracts on Ethereum and other EVM networks that lets users hold, send, swap and use tokens from private balances.
LiveShielded pool
Railgun's documentation lists its V2 contracts as live on Ethereum, BNB Chain, Polygon and Arbitrum, where DefiLlama put its TVL at about $114 million on 16 October 2026, about 96% of it on Ethereum; a Base deployment adopted on 31 August 2026 held less than $1.
- TVL
- $112.2MDefiLlama, 18 Oct 2026
- Launched
- Jul 2021
- Token
- RAIL
- Chains
- Ethereum, BNB Chain, Polygon and Arbitrum
How it works
Railgun is a set of smart contracts (code that runs on a blockchain) deployed on Ethereum, BNB Chain, Polygon and Arbitrum, the four networks its documentation lists. A user moves tokens from an ordinary public address into the contracts, a step Railgun calls shielding, and then holds them at a private Railgun address that begins with 0zk. No company or operator holds the funds: they sit in the contracts, and only the owner's keys can spend them. From the shielded balance a user can pay other 0zk addresses, or swap tokens and use other DeFi applications, without first withdrawing.
Balances are recorded as private notes, much like the coin records used by Bitcoin and Zcash, and the contracts track them through sealed fingerprints held in a Merkle tree. To spend, the user's wallet creates a zero-knowledge proof, a zk-SNARK using the Groth16 system, which convinces the contracts that the user owns enough unspent notes without revealing which notes they are, the token, the amount, the sender or the recipient. Because every transaction needs gas, users can pass the finished transaction to a broadcaster, an independent operator reached over the Waku peer-to-peer network, which submits it from its own public address in return for a fee taken from the shielded balance. On a block explorer the transaction then appears to come from the broadcaster rather than from the user.
Some things stay visible. Shielding is a normal public transaction that shows the sending address, the token and the amount, and unshielding sends tokens to a public address where their arrival can be seen. The contracts deduct 0.25% on every shield and unshield. Anyone can see that a Railgun transaction happened and when, and anyone a user gives a viewing key to can read that user's balances and history, though not spend from them. Wallets can also apply an optional layer called Private Proofs of Innocence, which screens new deposits against public lists of flagged transactions and addresses from providers such as Chainalysis, Elliptic and SlowMist; Railgun's software development kit for wallets has applied it on Ethereum since November 2023 and on the other three networks since mid-2024. Until a deposit passes, which takes at least a standby period of about an hour, it can only be sent back to the address it came from.
TVL over time
- $112.2M TVL now
- +16.2% in 30 days
- $137.9M highest daily TVL, 14 Aug 2025
Daily total value locked (TVL) from DefiLlama since 28 Jan 2022, with the current value refreshed every hour. The latest value is from 18 Oct 2026, 04:12 UTC. The series is in protocol-railgun.json, listed on the Data page.
What it hides and what it does not
What it hides
- Which notes are spent, and the token, amount, sender and recipient of each transfer, swap or other DeFi action made from a shielded balance.
- The user's own public address as the payer of gas, when a broadcaster submits the transaction: on a block explorer it appears to come from the broadcaster.
What it does not hide
- Shielding: the sending address, the token and the amount are public.
- Unshielding: the arrival of the tokens at a public address.
- That a Railgun transaction happened, and when.
- A user's balances and history, to anyone the user has given a viewing key.
Drawn from how it works, above; the sources are listed at the end of the page. Where privacy still leaks explains the patterns, such as timing and amounts, that can give users of any design away.
Audits
Ten security reviews, oldest first, with what each covered and found. Dates are when each report was issued, unless the entry says otherwise.
| Date | Firm | Scope and findings |
|---|---|---|
| ABDK Consulting | Railgun's first Solidity contracts (Commitments, RailgunLogic, Snark, TokenWhitelist, Types and Verifier) and Circom circuits (JoinSplit, MerkleTree and others). Version 2.0 of the report, which followed version 1.0 of 18 Jun 2021, lists 2 critical issues, both fixed, 4 major issues, 3 of them fixed and 1 (redundant hashing in Commitments.sol) left unchanged, and 57 moderate or minor issues, mostly fixed. Sources: Smart contract audit: Railgun, Circom and Solidity (version 2.0) ; Smart contract audit: Railgun, Circom and Solidity (version 1.0) |
|
| Hacken | The Railgun contract repository at one commit, covering governance, staking, voting, treasury, token distribution, proxy and privacy logic contracts, reviewed from 25 Oct 2021 for a client named Right to Privacy; 2 medium and 2 low-severity issues, with no critical or high-severity ones. Source: Smart Contract Code Review and Security Analysis Report for Right to Privacy |
|
| Zokyo | The same commit of the Railgun contracts, including the Delegator, Voting, Staking, Treasury, Distributor, VestLock, Commitments, RailgunLogic and Verifier contracts; no critical issues, and one low-severity and a few informational issues that were left unresolved because the contracts were already deployed. |
|
| Zokyo | The Commitments, Globals and RailgunLogic privacy contracts at a later commit; no critical issues, and the 2 issues found were resolved. |
|
| Zokyo | Privacy logic contracts at one commit: RailgunLogic, Commitments, Globals, Snark, Verifier, Poseidon and TokenBlacklist; no critical issues found. |
|
| Zokyo | The RAIL token contract (Rail.sol) as deployed on Ethereum; no critical issues found. |
|
| HashCloak | Railgun's version 2 zero-knowledge circuits, reviewed from 22 Mar 2022 to 29 Mar 2022, and the Voting contract and GovernorRewards treasury contract, reviewed from 22 Aug 2022 to 29 Aug 2022; 7 issues, 3 of them high severity and none critical, all reported as resolved. |
|
| Zokyo | The Voting governance contract; low-severity and informational issues, which Zokyo reported as resolved or acknowledged. |
|
| Zokyo | The Commitments, RailgunLogic and RailgunSmartWallet privacy contracts; no critical issues, and 2 medium-severity issues were resolved. |
|
| Zokyo | The Sender and Executor contracts, which sit in the Arbitrum folder of Railgun's governance code and link the Arbitrum deployment to governance on Ethereum; no critical issues, some medium, low and informational ones, and a warning that an admin address holds broad powers over cross-chain task execution. Sources: Smart contract audit: Railgun (version 1.0) ; contract/contracts/governance/arbitrum ; RAIL Token Overview |
Incidents
One incident that affected the project or its users.
-
The FBI said on 23 January 2023 that North Korea's Lazarus Group was behind the June 2022 theft from Harmony's Horizon bridge and that North Korean cyber actors had used Railgun on 13 January 2023 to launder more than $60 million of the stolen ether, and the analytics firm Elliptic estimated that about 70% of all funds sent through Railgun until then came from that theft. In April 2024 Railgun called this a false allegation and said its Private Proofs of Innocence system blocks such actors.
Sources: FBI Confirms Lazarus Group Cyber Actors Responsible for Harmony's Horizon Bridge Currency Theft ; FBI: North Korean hacking group Lazarus behind $100 million crypto heist ; Railgun refutes claims of North Korean laundering following price surge
Milestones
15 milestones, oldest first.
-
Railgun launched on Ethereum.
Source: Digital Currency Group announces $10M strategic investment with privacy-preserving project Railgun
-
The RAIL token contract was deployed on Ethereum.
Sources: RailToken contract creation transaction ; RailToken (RAIL) contract address details
-
Railgun deployed the privacy contract proxies that it still uses on Ethereum, Polygon and BNB Chain; the logic behind them has since been replaced several times through protocol requests.
Sources: Railgun privacy contract (proxy) creation transaction on Ethereum ; Railgun privacy contract (proxy) creation transaction on Polygon ; BNB Chain deployment record (proxy deployment block 17431925) ; ProxyUpgrade events on the Ethereum privacy contract
-
The first protocol request under Railgun's current voting contract upgraded the Ethereum contracts to the RailgunSmartWallet logic, which added shielding to any 0zk address and new transaction events.
Sources: Proposal for RailgunSmartWallet Upgrades (protocol request 0) ; Execution of protocol request 0 ; ProxyUpgrade events on the Ethereum privacy contract
-
Railgun's privacy contracts were deployed on Arbitrum, where the protocol is secured by RAIL staked on Ethereum.
Sources: Railgun privacy contract (proxy) creation transaction on Arbitrum ; RAIL Token Overview
-
A protocol request installed 54 new Groth16 circuits for Railgun's private transactions, produced by a trusted setup ceremony that closed on 26 December 2022 with 328 participants.
Sources: Advanced Circuits Upgrade (protocol request 5) ; Execution of protocol request 5 ; Trusted Setup Ceremony
-
Railgun's software development kit for wallets began applying Private Proofs of Innocence to new shields on Ethereum, followed by Arbitrum and BNB Chain on 20 June 2024 and Polygon on 22 August 2024.
Sources: network-config.ts (Private Proofs of Innocence launch blocks per network) ; Ethereum block 18514200 ; Arbitrum block 223895116 ; Polygon block 60907366
-
When the attacker behind the $9.5 million zkLend exploit tried to move the stolen funds through Railgun, they could only be sent back to the address they came from, DL News reported.
Source: Crypto privacy software refuses money stolen in $9.5m hack
-
Holders of locked RAIL passed a protocol request for what it called RAILGUN v2.5, which upgraded the logic contract on Ethereum, Polygon and Arbitrum and the circuits, with new randomness from an additional setup ceremony, to prepare for a version 3.
Sources: RAILGUN v2.5 Contract Upgrade Proposal (protocol request 17) ; Execution of protocol request 17 ; ProxyUpgrade events on the Ethereum privacy contract ; ProxyUpgrade events on the Polygon privacy contract ; ProxyUpgrade events on the Arbitrum privacy contract
-
Railgun's TVL reached its highest level to date, about $138 million, according to DefiLlama.
Source: Railgun protocol TVL data
-
The Ethereum Foundation introduced Kohaku, a reference privacy wallet and open-source wallet toolkit whose packages include a Railgun library, which the project's repository listed on 16 October 2026 as under maintenance, with all its packages marked as unaudited.
Sources: The Ethereum Foundation's Commitment to Privacy ; ethereum/kohaku ; Railgun token soars 300% as Ethereum Foundation integrates protocol into privacy wallet toolkit
-
DL News reported that Railgun had processed about $1.6 billion of shielded transactions so far in 2025 and about $4 billion since its 2021 launch.
Source: Railgun hits record $4bn in volume as privacy demand surges
-
A protocol request raised the share of the Ethereum treasury paid to active RAIL stakers every two weeks from 2.00% to 4.20% and minted 2.5 million new RAIL into the treasury.
Sources: Request Improving Active Rewards System (protocol request 24) ; Execution of protocol request 24, with its RAIL mint and reward-rate change events
-
A protocol request upgraded the privacy contracts on Ethereum, with Polygon and Arbitrum upgraded the same day and BNB Chain moved to the same new logic, adding event tags intended to speed up wallet balance scanning and Private Proofs of Innocence.
Sources: Security improvement request to improve scanning (protocol request 25) ; Execution of protocol request 25 ; ProxyUpgrade events on the Polygon privacy contract ; ProxyUpgrade events on the Arbitrum privacy contract ; BNB Chain deployment record (current implementation)
-
A protocol request executed on Ethereum adopted a new deployment of the privacy contracts on Base, to be governed by RAIL stakers on Ethereum through a new cross-chain messaging contract; by 16 October 2026 it had received one shield and held less than $1.
Sources: Base deployment of RAILGUN Privacy System (protocol request 27) ; Execution of protocol request 27 ; OPStackSender contract (Ethereum to Base governance messaging) ; Railgun privacy contract (proxy) on Base, address details ; Transactions sent to the Railgun privacy contract on Base
Funding
One source of funding. Amounts are in US dollars; a dash means the sources give no US dollar figure.
| Date | Round | Amount | Investors |
|---|---|---|---|
Strategic investment ($7.2 million to the Railgun DAO treasury and more than $3 million of RAILPOLY and RAILBSC purchases) Source: Digital Currency Group announces $10M strategic investment with privacy-preserving project Railgun |
$10M | Digital Currency Group |
Risks
Railgun's privacy depends on how many people use it and how they use it. Shields and unshields are public, so a deposit followed soon afterwards by a withdrawal of a similar amount can be matched, and the pools outside Ethereum are small: on 16 October 2026 DefiLlama counted about $3.2 million on Arbitrum, $0.9 million on BNB Chain and $0.5 million on Polygon, against about $109 million on Ethereum. A viewing key cannot be revoked once it has been shared. The Groth16 proofs rely on trusted setup ceremonies that stay sound only if at least one participant destroyed their secret contribution, and the contracts sit behind upgradeable proxies whose logic RAIL holders replaced in July 2025 and again in August 2026, while railgun.org lists no audit report later than February 2023. Private Proofs of Innocence is optional and depends on the list providers each wallet or user chooses, and in 2023 the FBI said North Korean hackers had laundered more than $60 million through Railgun, which Railgun disputes; the episode shows the compliance scrutiny that users and integrators can face.
Sources
The documents this profile rests on. Each audit, incident, milestone and funding round above also links its own sources.
- RAILGUN: On-chain ZK Privacy Ecosystem (home page, including the audit list)
- Overview
- RAILGUN Privacy System
- Privacy Overview
- Trusted Setup Ceremony
- Community Broadcasters
- Wallets and Keys
- Shielding Tokens
- Unshielding Tokens
- RAILGUN Deductions
- Private Proofs of Innocence
- RAIL Token Overview
- Decentralized Protocol Requests
- Helpful Links
- Common Misconceptions
- Railgun-Privacy
- BNB Chain deployment record
- network-config.ts (Private Proofs of Innocence launch blocks per network)
- Railgun privacy contract (proxy) on Ethereum, address details
- ProxyUpgrade events on the Ethereum privacy contract
- ProxyUpgrade events on the Polygon privacy contract
- ProxyUpgrade events on the Arbitrum privacy contract
- Railgun voting contract event log, including Execution events for protocol requests 24 to 27
- Proposal To Continue Funding Towards Research (protocol request 14)
- Proposal To Continue Funding Towards Research (protocol request 21)
- Proposal To Continue Funding Towards Research (protocol request 26)
- RAILGUN v2.5 Contract Upgrade Proposal (protocol request 17)
- Security improvement request to improve scanning (protocol request 25)
- Base deployment of RAILGUN Privacy System (protocol request 27)
- Railgun privacy contract (proxy) on Base, address details
- Railgun protocol TVL data
- Digital Currency Group announces $10M strategic investment with privacy-preserving project Railgun
- FBI Confirms Lazarus Group Cyber Actors Responsible for Harmony's Horizon Bridge Currency Theft
- FBI: North Korean hacking group Lazarus behind $100 million crypto heist
- Railgun refutes claims of North Korean laundering following price surge
- The Ethereum Foundation's Commitment to Privacy
