RAILGUN

• Name: RAILGUN
• URL: https://railgun.org/
• Category: onchain privacy infrastructure / zk wallet middleware / private smart-contract interaction protocol
• Tags: ethereum-ecosystem
• Summary: RAILGUN is EVM privacy middleware, not a separate privacy chain. The useful split is the shielded-balance layer, broadcaster submission path, wallet and SDK integration surface, and the assurance tooling that makes disclosure selective rather than absent.
• What it does:
  • Lets users shield assets into RAILGUN smart contracts and then privately transfer, swap, lend, borrow, or interact with supported smart contracts
  • Hides sender, recipient, token type, and amount through zk-SNARK-based private balances and a UTXO-style encrypted Merkle-tree model
  • Uses community-built integrated wallets plus developer SDKs so privacy can be added to wallets and dapps without requiring a separate execution chain
  • Routes submissions through broadcasters so private interactions appear on public scanners as broadcaster-originated rather than directly from a user’s shielding address
  • Exposes an assurance layer with viewing keys, Private Proofs of Innocence (PPOI), and Koinly tax exports to support auditability, investigations, and compliance-sensitive workflows
  • Maintains a separate RAIL governance token for protocol governance and security rewards, while the docs emphasize that holding RAIL is not required to use the privacy system
• Key claims:
  • The docs say RAILGUN is built directly on-chain for Ethereum, BSC, Polygon, and Arbitrum, and that the code has no owner
  • The docs say RAILGUN is 100% non-custodial and that users do not need to move to a separate privacy chain or trusted bridge to get privacy
  • The privacy-system docs say RAILGUN privatizes sender, recipient, token type, and amount while supporting private DeFi interactions and arbitrary smart-contract calls
  • The assurance docs highlight three main auditability tools: viewing keys, Private Proofs of Innocence, and Koinly tax exports
  • The governance docs describe RAIL as a governance/security token where locked RAIL confers voting power, proposal rights, and delegation rights, but the overview explicitly says RAIL is not required for protocol use and is not itself a privacy coin
  • The GitHub org and wallet SDK repo show that the project’s real operational surface includes SDKs, developer tooling, broadcaster examples, and wallet-integration code rather than only a consumer-facing wallet app
• Whitepaper: No official standalone whitepaper or litepaper was found in the first-party docs during this pass. The docs portal and GitHub repositories appear to be the main source of truth; see ../whitepapers/railgun-primary-sources-2026-04-26.md.
• Sources:
  • https://railgun.org/
  • https://docs.railgun.org/
  • https://docs.railgun.org/wiki/learn/overview.md
  • https://docs.railgun.org/wiki/learn/privacy-system
  • https://docs.railgun.org/wiki/assurance/railgun-assurance-suite
  • https://docs.railgun.org/wiki/rail-token/protocol-governance
  • https://github.com/Railgun-Community
  • https://github.com/Railgun-Community/wallet

Internal linkages

• Best smart-contract privacy and compliance-conditioned privacy reads: privacy-pools and mystiko.
• Keep the note on private EVM execution and selective disclosure, not on generic privacy-coin rhetoric.

Control surface

• Practical authority sits in contract and circuit upgrades, broadcaster coverage, wallet-integration defaults, assurance-tool policy, and which downstream smart-contract interactions the stack keeps smooth.

• The code may be ownerless at the protocol layer, but privacy UX still depends on middleware, relaying, and disclosure tooling that somebody ships and operates.

• Read RAILGUN as private smart-contract middleware with audit hooks, not as a self-contained privacy chain.

• Last reviewed: 2026-06-12 UTC