Raindex is a programmable, dynamic onchain order book. Orders are not static limit orders — they are strategies written as Rain interpreter expressions that evaluate at match time. This means order amounts and ratios can change based on onchain state, time, oracle prices, or any other logic the expression author encodes. Two orders clear when their evaluated ratios overlap, with any surplus going to the clearer as a bounty.
Traditional onchain order books (e.g. dYdX, Serum) replicate the familiar limit-order model: users place fixed-price bids and asks, a matching engine pairs them, and fills execute at the stated price. This works, but each repricing requires a new transaction, making active market-making expensive and slow.
Raindex replaces static prices with executable expressions. An order's ratio and maximum amount are computed fresh every time someone attempts to match it. The expression can read any onchain state — block number, oracle feeds, vault balances, its own persistent storage — so a single order can implement strategies that would otherwise require off-chain bots continuously cancelling and reposting.
AMMs (Uniswap, Curve, Balancer) achieve always-on liquidity by pooling tokens into a shared reserve governed by a bonding curve. Liquidity providers deposit tokens and receive pool shares; the curve mechanically sets the price. This removes the need for active order management but introduces impermanent loss, pool-level MEV extraction, and limited strategic control for individual LPs.
Raindex keeps individual ownership of tokens in per-user vaults — there is no shared pool. Each order owner defines their own pricing logic, so there is no bonding curve imposing a single price on all participants. Because orders evaluate independently, one user's strategy cannot dilute or override another's. Clearers (analogous to AMM arbitrageurs) match overlapping orders and keep the surplus, providing the same "always available" clearing incentive that arbitrageurs provide to AMMs, but without requiring passive LPs to share a pool.
This repo defines the Solidity interfaces and types for Raindex. It does not contain the implementation.
Uses nixos.
Install nix develop - https://nixos.org/download.html.
Run nix develop in this repo to drop into the shell. Please ONLY use the nix
version of foundry for development, to ensure versions are all compatible.
Read the flake.nix file to find some additional commands included for dev and
CI usage.
Everything is under DecentraLicense 1.0 (DCL-1.0) which can be found in LICENSES/.
This is basically CAL-1.0 which is an open source license
https://opensource.org/license/cal-1-0
The non-legal summary of DCL-1.0 is that the source is open, as expected, but also user data in the systems that this code runs on must also be made available to those users as relevant, and that private keys remain private.
Roughly it's "not your keys, not your coins" aware, as close as we could get in legalese.
This is the default situation on permissionless blockchains, so shouldn't require any additional effort by dev-users to adhere to the license terms.
This repo is REUSE 3.2 compliant https://reuse.software/spec-3.2/ and compatible
with reuse tooling (also available in the nix shell here).
nix develop -c rainix-sol-legal
Contributions are welcome under the same license as above.
Contributors agree and warrant that their contributions are compliant.