Founded in 2017 as Archain, the company changed its name to Arweave in 2018 while completing the Techstars Berlin mentorship program. Arweave’s mission is to make permanent, low-cost storage a reality. The company aims to accomplish its goal with the Arweave network, a block-based data structure called a “blockweave”.

Arweave’s blockweave underpins the Arweave permaweb, an array of data, websites, and applications that are hosted on the blockweave. Since the Arweave protocol is built on top of the HTTP protocol, the permaweb is accessible via modern web browsers like Brave or Google Chrome. Aiming to store data on the network in perpetuity, the Arweave protocol enables individuals with spare hard drive space to store data in exchange for AR tokens. Arweave anticipates that the cost of storage will continue to decrease and uses a formula to calculate how much it will cost to store a particular piece of data. All of Arweave’s assumptions can be found in its yellowpaper.

The Arweave mainnet launched in June of 2018 with a select group of 1800 hand-picked participants across various countries. Before the launch, the Arweave team also conducted an initial token sale limited to whitelisted individuals.

In November of 2019, Arweave secured a $5 million funding round from several venture capital firms in exchange for $5 in Arweave tokens. Six months later, the Arweave team raised another $8.3 million in exchange for AR tokens. However, after this round, the firm stated that it would use the new funds to incentivize community adoption and growth.

Users pay AR tokens in order to add data to the Arweave network where it can be accessed via web browsers on Arweave’s permaweb. Users pay the cost that Arweave has predicted will be sufficient to store the data forever. For more about how to archive a page please read Arweave’s documentation.

Consensus
Arweave intends to use Proof of Access for its blockweave data structure to prove data is stored securely over time within its network. Proof of Access randomly selects a prior block – termed the recall block – and mandates that miners are able to provide specific data from the recall block (e.g. the block list hash). This process occurs for each block in the blockweave structure.

Mining
Miners are compensated from mining block from two sources – inflation and transaction fees.

During the blockweave block creation process, if a miner is unable to access the data from the selected “recall block”, the miner is not permitted to verify the new block or claim the block reward. Arweave claims that this will incentivize miners to store as much information/blocks of the Arweave protocol as possible.

Each transaction to store data immediately uses a portion of the user’s AR token to pay the transaction fee while the rest is held in a network endowment which is used to pay the cost of storage in perpetuity. Prior to joining the Arweave network, all miners must download the most recent block which contains the hash list and wallet list (see technology section).

In some cases, a miner can be compensated by a third source – a reward from the existing storage endowment.

The Arweave team has implemented a few core technologies for the Arweave protocol including blockweave, Proof of Access, wildfire, and blockshadows.

Blockweave and Proof of Access
Arweave’s protocol combines a new data structure called a “blockweave” and a new consensus mechanism termed Proof of Access (PoA). As the name suggests, the blockweave protocol utilizes a block-based structure where each block is linked to two blocks:
The most previous block in the Arweave blockweave
The recall block, a randomly selected block within the protocol’s history. The recall block is determined by taking the hash of the current block and calculating its modulus with respect to the current block height.
Miners must provide hashes from both of the prior blocks in order to create a new block and earn the block reward in the form of Arweave’s native token (AR).

Node Architecture
The protocol introduces variances to Bitcoin’s node structure in which each node stores a block hash list – a list of the hashes of all previous blocks – designed to allow old blocks to be verified. Additionally, nodes possess a wallet list which contains a list of all “active wallets” in the protocol.

Wildfire
Arweave also utilizes a data-sharing system called “wildfire” whereby Arweave nodes are ranked based on the speed at which each node responds to requests and accepts data from other nodes in the network. Nodes that fail to quickly share information can be blacklisted from the Arweave network permanently. The design is aimed at incentivizing good behavior amongst nodes in the network.

Blockshadows
Further, Arweave implements another data management system called “blockshadows” – a process in which transactions are partially decoupled from blocks in favor of only sending other nodes a minimal block (the shadow) that enables other nodes in the network to re-create the full block. Blockshadows contain a hash of the wallet list, hash list, and a list of transaction hashes from the current block.

Permaweb
Another notable aspect of Arweave’s network is the “permaweb” which sits atop of Arweave’s data storage layer. The permaweb is the human-readable layer that contains the collection of documents and applications of which the data is stored permanently on the Arweave protocol. Because the Arweave network is built on top of the HTTP protocol, browsers have the ability to access permaweb documents and applications.

The Arweave protocol supports a blacklist system by which any node has the option to blacklist content that an individual or group of nodes wishes to reject. Content that is rejected by more than half the network will be rejected across the entire network.