Sablier Flow

In-depth documentation is available at docs.sablier.com.

Background

Sablier Flow is a debt tracking protocol that tracks tokens owed between two parties, enabling open-ended token streaming. A Flow stream is characterized by its rate per second (rps). The relationship between the amount owed and time elapsed is linear is be defined as:

$$\text{amount owed} = rps \cdot \text{elapsed time}$$

Sablier Flow can be used in several areas of everyday finance, such as payroll, subscriptions, grant distributions, insurance premiums, loans interest, token ESOPs etc. If you are looking for vesting and airdrops, please refer to our Lockup protocol.

Features

1. Open-ended: A stream can be created with no specific end time. It runs indefinitely until it is paused or voided.
2. Top-ups: No upfront deposit requirements. A stream can be funded with any amount, at any time, by anyone, in full or partially.
3. Pause: A stream can be paused by the sender and can later be restarted without losing track of previously accrued debt.
4. Void: A voided stream cannot be restarted anymore. Voiding an insolvent stream forfeits the uncovered debt. Either the sender or the recipient can void a stream at any time.
5. Refund: Unstreamed amount can be refunded back to the sender at any time.
6. Withdraw: A publicly callable function as long as to is set to the recipient. A stream's recipient is allowed to withdraw funds to any address.

Install

Node.js

This is the recommended approach.

Install Flow using your favorite package manager, e.g. with Bun:

bun add @sablier/flow

Then, if you are using Foundry, you need to add these to your remappings.txt file:

@sablier/flow/=node_modules/@sablier/flow/
@openzeppelin/contracts/=node_modules/@openzeppelin/contracts/
@prb/math/=node_modules/@prb/math/

Git Submodules

This installation method is not recommended, but it is available for those who prefer it.

Install the submodule using Forge:

forge install --no-commit sablier-labs/flow

Then, install the project's dependencies:

forge install --no-commit OpenZeppelin/[email protected] PaulRBerg/prb-math#95f00b2

Finally, add these to your remappings.txt file:

@sablier/flow/=lib/flow/
@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
@prb/math/=lib/prb-math/

Usage

This is just a glimpse of Sablier Flow. For more guides and examples, see the documentation and the technical file.

import { ISablierFlow } from "@sablier/flow/src/interfaces/ISablierFlow.sol";

contract MyContract {
  ISablierFlow immutable flow;

  function doSomethingWithFlow(uint256 streamId) external {
    uint128 totalDebt = flow.totalDebtOf(streamId);
    // ...
  }
}

Contributing

Feel free to dive in! Open an issue, start a discussion or submit a PR. For any concerns or feedback, please join our Discord server.

Refer to CONTRIBUTING guidelines if you wish to create a PR.

License

The primary license for Sablier Flow is the Business Source License 1.1 (BUSL-1.1), see LICENSE.md. However, there are exceptions:

• All files in src/ with the exception of SablierFlow.sol are licensed under GPL-3.0-or-later. Refer to LICENSE-GPL.md for preamble.
• All files in script/ are licensed under GPL-3.0-or-later.
• All files in tests/ are unlicensed (as indicated in their SPDX headers).