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Architecture overview

Salt coordinates signing workflows without becoming a signer.

Signing authority stays with the participants that make up an account’s quorum. The Salt Coordination Layer coordinates the workflow between those participants, evaluates policy, and helps account creation and transaction signing ceremonies complete.

Signing authority means an entity that contributes a signature to a signing quorum in order for a transaction to be submitted to the chain.

Salt does not custody user key material and cannot sign transactions.

Primary components​

Salt has four primary components:

  • Salt SDK — the programmatic interface for applications, agents, and embedded fintech flows
  • Salt App — the browser interface
  • Salt Coordination Layer — the coordination and policy layer
  • Robo Guardians — automated co-signers run on infrastructure chosen by the organisation
+------------------------------+    +------------------------------+
| Signer participant           |    | Robo Guardian                |
|                              |    |                              |
| A person or software service |    | Automated co-signer          |
| Holds signing authority      |    | Holds signing authority      |
+---------------+--------------+    +---------------+--------------+
                |                                   |
                | API / WebSocket coordination      |
                |                                   |
                +----------------+  +---------------+
                                 |  |
                                 v  v
+--------------------------------------------------------------+
| Salt Coordination Layer                                      |
|                                                              |
| Authenticates users, evaluates policy, and coordinates       |
| account creation and transaction signing workflows           |
| Does not hold signing authority                              |
+--------------------------------------------------------------+
                                |
                                | Final signed transaction
                                v
+--------------------------------------------------------------+
| Blockchain network                                           |
+--------------------------------------------------------------+

How signing works​

A transaction begins with a proposal from a user, application, bot, or agent.

The Salt Coordination Layer receives the proposal and checks it against the account’s active policies. If the proposal satisfies policy, the coordination layer connects the required quorum participants for signing.

The participants perform the cryptographic signing operations from their own environments. Once the signing threshold is reached, the signed transaction can be assembled and broadcast.

The blockchain only sees the final signed transaction. It does not know which Salt policies were checked or which participants cosigned the transaction.

Salt SDK​

The Salt SDK is the primary programmatic interface for Salt.

It provides the software for authenticating users, creating organisations and accounts, configuring policies, proposing transactions, and participating in signing workflows.

The SDK can be used from browser apps, Node.js processes, fintech apps, bots, agents, or other services that need controlled access to Salt accounts.

Salt App​

The Salt App is the browser interface that provides a visual workspace for creating organisations, adding collaborators, configuring policies, creating accounts, and proposing transactions.

The Salt App is built on the same underlying system exposed through the Salt SDK. It is not required to use Salt.

Salt Coordination Layer​

The Salt Coordination Layer handles:

  • authentication
  • organisation management
  • collaborator permissions
  • policy configuration
  • policy evaluation
  • real-time coordination between signing participants

It exposes APIs and WebSocket connections used by the Salt SDK, Salt App, and Robo Guardians.

Robo Guardians​

Robo Guardians​

Each organisation has dedicated Robo Guardians. Robo Guardians function as a Salt Organisation’s automated risk department, run by the entity that creates the Salt Organisation.

They hold one part of an organisation’s signing quorum and are designed to stay online when human signers are not. Their role is to participate in account creation and transaction signing workflows when the relevant policy conditions are satisfied.

They do not broadcast transactions, but contribute to the signing quorum required for a transaction to be submittable.

Each organisation chooses where its Robo Guardians run. They can be hosted on the organisation’s own hardware or cloud environment, or by a third party the organisation chooses to trust.

Robo Guardians maintain outbound WebSocket connections to the Salt Coordination Layer, allowing them to participate in signing workflows without exposing inbound ports.

Design principles​

Salt’s architecture follows three core principles.

  • Coordination without custody: Salt coordinates account workflows, policy checks, and signing ceremonies, but signing authority stays with quorum participants.
  • Policy before signature: Transaction proposals are checked against policy before automated co-signers are asked to participate.
  • Automation outside Salt-controlled infrastructure: Robo Guardians ensure automated execution can run 24/7, but they run on infrastructure chosen by the organisation, not infrastructure controlled by Salt.