Explaining IOST’s Proof of Believability consensus

You've probably heard of Proof of Work (PoW) and Proof of Stake (PoS), but what about IOST's Proof of Believability (PoB) consensus?

You probably already know about Proof of Work (PoW) and Proof of Stake (PoS) by now. If you’ve been digging a little deeper into other cryptocurrencies besides Bitcoin and Ether, you may also know about consensus algorithms such as Delegated Proof of Stake (DPoS) and Proof of Authority (PoA). But what about IOST’s Proof of Believability (PoB)?

How does one of the hottest application-friendly platforms that recently surpassed Ethereum in daily dApp transaction volume reach consensus on its network? Let’s take a closer look.

What is Proof of Believability (PoB)?

Proof of Believability (PoB) is the consensus algorithm used by the IOST blockchain. According to IOST communications lead Joshua Bass in a recent interview, it’s a “first-of-a-kind mechanism”. So what makes it so different from other consensus algorithms out there?

Proof of Believability has a few advantages over Proof of Work. It enables high transaction speed without compromising network security. In order to achieve this, it uses several factors including how many IOST tokens the node holds, its reputation, its contribution, and its behaviour.

Proof of Believability requires significantly less computational power than Proof of Work. It also tackles the scalability problem head-on. PoB uses elements such as microstate blocks and a dynamic sharding protocol to reduce storage, processing power, and cost to keep transaction throughput high and secure. As Bass commented:

“PoB eliminates the need for an energy-hungry Proof of Work protocol, which stands as a barrier to blockchain becoming widely adopted. With the PoB system, a node is validated based on its past contributions and behaviours.”

How does Proof of Believability maintain decentralisation of the network?

To maximise fairness and the decentralised nature of the blockchain, IOST uses a reputation-based system called Servi. These are non-tradeable tokens that are given to good actors in the IOST ecosystem. They are a major factor in how validating nodes are chosen.

Bass enthused: “What makes Servi unique is that upon winning the right to validate transactions, a user’s Servi balance is cleared, making it far harder for a ‘rich get richer’ scenario to develop.”

According to the IOST team, Proof of Believability is even more efficient than Proof of Stake as it takes various elements into consideration. Not only does it rely on the token balance, but also on the nodes’ “believability score”, which is based on the following factors:

  • How many IOST tokens are stored in the node
  • Number of Servi tokens earned
  • How many positive reviews the node has
  • Node transaction and action history


To achieve consensus fairly, the IOST network algorithmically selects a set number of validators per block randomly. The nodes that have a higher believability score are more likely to be selected. That isn’t to say that the same nodes are always chosen, however.

In order to maintain a fair system and level playing field for all, PoB continuously selects random validators from the good actors in the ecosystem.

What is IOST aiming to achieve?

“Our goal is to create the world’s fastest blockchain infrastructure that meets the scalability and security needs of a decentralised economy,” Bass explained.

The main verticals that IOST concentrates on are software development, gaming, fintech, media, and entertainment, as well as other areas that can benefit from blockchain technology.

Proof of Believability may sound strange at first. But according to IOST, there’s no other consensus algorithm that is as effective and doesn’t compromise on decentralisation. Bass said:

“Sadly, many blockchain projects have deviated from the original vision and fail to uphold true decentralisation and immutability. Some examples include Ethereum rushing a ‘soft fork’ comprised of minor changes in the Ethereum blockchain code for the sole purpose of censoring transactions, and EOS forming a centralised judging committee that has the ability to decide what is right and wrong, which completely overrides the promised immutability of blockchain.”

IOST maintains that it adheres to the egalitarian and democratic values of the blockchain by remaining trustless, immutable, and censorship-resistant.

Bass stated: “PoB is crucial in this system as it allows what we believe to be the ideal compromise in the scalability trilemma.”

With IOST launching its mainnet six months ahead of schedule in February, it will be interesting to see how this project evolves and whether Proof of Believability will become a new standard.

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