flow

Sablier Flow

Important

The license changed from BUSL-1.1 to GPL on 2026-07-13. Read the announcement on X for details.

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 and 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

Git Submodules

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

Install the monorepo and its dependencies using Forge:

forge install sablier-labs/evm-monorepo@flow@v3.0.1 OpenZeppelin/openzeppelin-contracts@v5.3.0 PaulRBerg/prb-math@v4.1.0

Then, add the following remappings in remappings.txt:

@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
@prb/math/=lib/prb-math/
@sablier/evm-utils/=lib/evm-monorepo/utils/
@sablier/flow/=lib/evm-monorepo/flow/

Usage

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

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

contract MyContract {
  ISablierFlow immutable flow;

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

Deployments

The list of all deployment addresses can be found here.

Security

The codebase has undergone rigorous audits by leading security experts from Cantina, as well as independent auditors. For a comprehensive list of all audits conducted, please click here.

For any security-related concerns, please refer to the SECURITY policy.

Contributing

This repository is not accepting pull requests of any kind, including changes to code comments. Comment-only edits can change the compiled bytecode, and the source on main must remain byte-for-byte verifiable against the deployed addresses. PRs will be closed without review.

For questions or informal feedback, open an issue or start a discussion.

License

See LICENSE.md.