Sea Protocol: Order-Book and AMM DEX on Aptos and Sui

What Sea Protocol is and who it was built for

Sea Protocol is a decentralized exchange protocol written in Move for the Aptos and Sui blockchains. Its stated goal is to let anyone trade any asset at any time without a central intermediary. The protocol combines two exchange mechanisms: a central limit order book (CLOB) for price-discovery trades, and an automated market maker (AMM) for passive liquidity. Most DEXes on Ethereum and Solana pick one approach or the other. Uniswap v2 and Curve are AMM-only. Serum (now defunct) was order-book-only. Sea Protocol tries to offer both in a single contract.

The EVM version of the project has moved to the GridTrade repository at gridtrade.xyz. The current repository under `sea-protocol/seaprotocol` focuses on the Aptos and Sui implementation. The repository received its last commit on 2026-03-02, which is over six months before the date of this review, and has no GitHub releases. Developers evaluating it for production use should treat it as a reference codebase rather than an actively maintained framework.

How grid orders work in Sea Protocol

Grid trading places a series of buy and sell orders at regular price intervals. When a sell order fills, the protocol replaces it with a buy order one step below. When a buy order fills, it becomes a sell order one step above. This mechanical flip earns the spread on every round trip.

The README gives a concrete example. Alice places a grid with eight orders: four sells at prices 100, 101, 102, and 103, and four buys at prices 95, 96, 97, and 98, each for 2.5 units of the base asset. If the sell order at price 100 fills, Alice receives 250 units of quote. The protocol then creates a new buy order at price 99 for 2.5 base units. If that buy fills, it flips back to a sell at 100. The grid continues cycling as long as the price stays within the defined range.

The README states that Sea Protocol allows cancelling any order within a grid at any time, which gives the liquidity provider more control than a fixed AMM position. The README also notes that Uniswap v3 is effectively a special case of a ranged grid order, which is the conceptual bridge between AMM and order-book mechanics.

Zero-spread stable coin swaps via post-only orders

Sea Protocol includes a mechanism the README calls zero spread. Two users can place post-only orders on opposite sides of the book at the same price. For a USDT/USDC pair, there can be both a sell order at price 1 and a buy order at price 1. Any taker can swap USDT for USDC at price 1 with no spread.

This is a meaningful design for stable coin pairs where both sides of the market expect parity. A conventional AMM always charges the configured fee percentage regardless of whether the price deviation from parity is trivial. A zero-spread order-book mechanism lets counterparties match at par. The constraint is that both buy and sell liquidity must be present at the same price, which requires enough market makers to keep both sides populated.

The README does not describe slippage handling for large trades against a thin book, and does not document what happens to the post-only mechanics when the peg drifts. That limitation means the zero-spread feature works best in stable conditions.

Price formula and coin decimal handling

Aptos and Sui represent coin balances as unsigned 64-bit integers. A coin with 8 decimal places stores 1.00000000 as the integer 100000000. The README documents the price formula in terms of these integer amounts and a price coefficient. Without scaling, price equals quote volume divided by base volume. When coin scales are included, the formula adjusts each amount by its respective scale factor. The README defines price_ratio as the price coefficient multiplied by the base scale divided by the quote scale, which simplifies the final price expression:

price_ratio = price_coefficient * base_scale / quote_scale

The README recommends a maximum of 8 decimal places for coins because the underlying balance type is u64. Coins with more decimal places would overflow or lose precision in the price formula. This is a hard constraint of the integer arithmetic, not a configurable parameter.

The pair's minimum lot size is not fixed at pair creation. According to the README, it is set when the first trade executes, and it can be modified whenever the trade price updates. The minimum lot size exists to protect against Sybil attacks where many tiny orders are placed to clog the order book.

Trading-is-mining token incentive model

A conventional AMM distributes fee revenue only to liquidity providers. Uniswap v2 gives all trading fees to LPs; traders pay the fee but receive nothing beyond their trade. The Sea Protocol README describes this as unfair to traders and states that the protocol's token will split incentives equally: 50% to traders and 50% to liquidity providers.

The README calls this mechanism trading-is-mining. It does not describe the specific token name, supply, or emission rate. The incentive design acknowledges that traders pay both trade fees and gas fees, and the mining component is meant to offset that cost over time.

The README does not document how the protocol measures trading volume for incentive attribution, how it handles wash trading, or what happens when the mining emissions exhaust a fixed supply. These are open design questions that would need to be answered before building on top of this mechanism.

Running the test suite

The repository uses the Aptos Move build tool. The README includes a test command:

aptos move test -i 1000000000

The `-i` flag sets the maximum number of instructions for the Move virtual machine during test execution. Setting it to 1,000,000,000 gives the test suite a large execution budget, which is necessary for tests that simulate many order placements or grid flips. The repository structure has a `src/` directory for the Move sources. Running the tests requires the Aptos CLI installed locally.

There are no integration tests or end-to-end tests documented in the README. The repository does not describe a local testnet setup or a deployment script for Sui. Anyone running this code against a real testnet would need to consult the Aptos and Sui documentation for deployment steps, as the README does not provide them.

Comparison with Uniswap v3 and maintenance status

Uniswap v3 is an Ethereum AMM with concentrated liquidity. It operates on EVM-compatible chains and is deployed and audited on Ethereum mainnet. Its liquidity positions are range-bounded, which the Sea Protocol README acknowledges as a special case of a grid order. The key difference is execution environment: Uniswap v3 runs on the EVM, while Sea Protocol targets Move on Aptos and Sui. Move's ownership model and parallel execution differ from the EVM, which affects how contract state and order books are structured.

For a team building on Aptos or Sui who wants an order-book exchange, Sea Protocol provides a reference design. For a team targeting Ethereum or any EVM chain, the GridTrade repository is the continuation of this project's EVM work. For a team that needs audited, battle-tested contracts with active security support, Uniswap v3 on Ethereum is the more mature option.

The last push to the `sea-protocol/seaprotocol` repository was on 2026-03-02. The repository has had no releases and no commits since that date. The LICENSE file should be reviewed before forking or redistributing any code from this repository.

Editorial conclusion

Sea Protocol is relevant to developers studying Move-based DEX design and grid order mechanics on Aptos or Sui. It is not a suitable base for a new production exchange: the repository has had no commits since 2026-03-02 and the EVM version has moved to a different repository at gridtrade.xyz. Anyone evaluating it should read the LICENSE file before forking, verify that the grid order logic handles edge cases for their chosen pair, and check the gridtrade repository to see whether the original team is continuing development there.

Frequently asked questions

Official sources

1. Issues
2. Project website
3. README
4. sea-protocol/seaprotocol on GitHub