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This week, we take a look at a recently announced Layer 1 blockchain, Aptos. Read on for a brief overview of the project, its incentivized testnet and development roadmap.

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Move-based blockchains have recently been widely discussed on Twitter, namely Aptos and Sui. We covered Sui in an earlier article 

. Since Ethereum, there have been many new Layer 1 blockchains aiming to solve various issues that its predecessors struggled to solve. Blockchains struggle to balance the trilemma of decentralization, scalability, and security, with most aiming for scalability in order to facilitate adoption. 

Aptos is a Layer 1 blockchain that aims to solve reliability, scalability, and usability issues that have plagued existing Layer 1s, whilst possessing security features lacking in EVM-based blockchains. Aptos uses Move, a Rust-based programming language created for Diem, a now abandoned blockchain project by Meta (formerly Facebook). 

The Aptos network can achieve over 130k transactions per second thanks to its parallel execution engine (

). This high throughput naturally results in low transaction costs for users on the network. 

With the Aptos whitepaper yet to be released, we will give a brief overview of the network based on publicly available information.

Aptos is founded by Aptos Labs, co-founded by Mo Shaikh and Avery Ching. Both co-founders, along with a few other team members worked together at Meta on the Diem blockchain project and founded Aptos Labs together to continue building on the technology they had originally developed for Diem. 

The rest of the Aptos Labs team consists of PhDs, researchers, engineers, designers, and strategists, a full list of which can be found 

It is evident that the team at Aptos Labs are highly experienced, and confident in their ability to build Aptos to be a safe, scalable, and accessible network. 

Aptos closed their first raise in March 2022, in a $200 million round led by a16z Crypto, with participation from big-name VCs such as Multicoin Capital, Three Arrows Capital, Hashed, Tiger Global, FTX Ventures, and Coinbase Ventures, among others. According to a 

 by CoinDesk, the round was closed at a valuation of $2 billion. 

 a $150 million funding round led by FTX Ventures and Jump Crypto, with participation from Apollo, Griffin Gaming Partners, Franklin Templeton, Circle Ventures, Superscrypt, and continued support from a16z crypto and Multicoin.

This brings the total funding raised by Aptos to $350 million.

Aptos is currently able to achieve up to 

 transactions per second (TPS) with 32 cores in an execution-only (without consensus) benchmark on devnet. This is made possible by leveraging on a couple of key factors. 

Decoupling of the Consensus Protocol and Execution Pipeline

The first and major step was to decouple the consensus protocol from transaction execution. Typically, a consensus protocol agrees on transactions and their order of execution and results. Aptos decouples the process, allowing both to run in parallel, removing their co-dependency and thus increasing throughput and lowering latency. 

Using Block-STM technology, which is a parallel execution engine for smart contracts, Aptos is able to further increase throughput. Block-STM comprises of the following core techniques:

Transactions are executed optimistically in parallel and validated post-execution, while unsuccessful validations are re-executed. 

A multi-version data structure is used to avoid replicated transaction conflicts. This means that when a transaction reads a memory location, it obtains the value written by the previous transaction, along with its associated version. 

During a transaction execution, a read-set and write-set is recorded. During validation, all memory locations in the read-set are read and the results compared to corresponding versions stored in the read-set. 

A collaborative scheduler coordinates validation and execution tasks among threads. Since transactions have a preset order, successful validation of a transaction execution does not guarantee that it can be completed — for example if a previous transaction was aborted and re-executed. Thus, the collaborative scheduler prioritizes execution and mitigates this issue.

When a validation fails, the values of the transaction’s last execution are used to estimate dependencies. This results in estimates being generated only when needed and are generally based on a state much fresher than at the beginning of the block. 

Aptos’ fourth iteration of their Byzantine Fault Tolerant (BFT) engine is able to achieve sub-second finality through their parallel execution engine. The BFT protocol analyzes on-chain states, and automatically updates validator rotations in order to adjust for non-responsive validators without human intervention, maintaining decentralization of the network. 

We talked about Move in our article about 

. The Move programming language makes parallel execution of transactions possible, which is what makes both Aptos and Sui unique from most other Layer 1s. 

Unlike Sui, which uses a novel implementation of Move, Aptos uses Move’s original object model for global storage. Sui’s 

 explains how their implementation of Move differs from Core Move.

The overall security of the Aptos network relies on the correct implementation of its validators, Move modules, and the Move VM. Therefore, Aptos has implemented a strict process to ensure quality of development, and can enforce strict requirements for code reviews and testing. 

The following aspects of the protocol also ensure improved security of the network. 

The Move programming language was designed for safer resource management, as well as deterministic and hermetic transaction execution. This means that transaction execution results are completely predictable, and based only on information contained in the transaction. Move is also robust against denial of service (DOS) attacks at the transaction execution level. 

The BFT protocol ensures that if the network is unreachable or compromised, the chain will not fork as long as the BFT honesty guarantees remain true. Furthermore, the BFT consensus protocol is both audited and formally 

The Aptos team has made further extensions that increase resistance of the BFT protocol, as detailed in this 

IT4: Dynamic Validator Topology (August 2022)

As of the time of writing, Aptos is currently on 

, which concluded on July 22, 2022. The team posts regular updates on their incentivized testnet progress on their 