Bittensor (TAO)

What Bittensor is

Bittensor is an open network in which independent subnets produce digital commodities such as compute, inference, storage and prediction, and the chain pays contributors in its native token, TAO. The blockchain itself is called subtensor, a Substrate-based chain that produces a block every 12 seconds. TAO has a hard cap of 21 million and is issued through a halving schedule (source: Bittensor documentation, September 2026).

The work does not happen on-chain. Subnets are off-chain competitions; the chain records who participates, measures agreement about who is doing good work, and distributes tokens accordingly.

How it works

Four roles define the system. Miners produce whatever a subnet's incentive mechanism demands. Validators score the miners by setting weights. Subnet owners define the incentive mechanism and set the subnet's parameters. Stakers back validators with TAO and share in the rewards.

Each subnet is identified by an integer and holds at most a fixed number of participants, defaulting to 256 slots with at most 128 validators. Registering on a full subnet evicts the lowest-ranked participant that is not still inside its immunity period. Netuid 0 is the root network, which has no miners and no subnet token; it is simply where TAO is staked directly.

At the end of each subnet's cycle, Yuma Consensus aggregates the validators' weights, weighted by their stake, into ranks, trust and incentive scores that determine payouts. This is separate from blockchain consensus, and conflating the two is the most common misunderstanding of Bittensor.

Blockchain consensus is currently permissioned. The documentation states plainly that "Subtensor currently uses Proof of Authority (PoA) for blockchain consensus," with Aura assigning block-production slots to an authorized validator set and GRANDPA finalizing the chain once more than two-thirds of authority voting weight agrees. Only approved authorities can author blocks or vote on finality; running a node or holding TAO does not admit you to that set. The published roadmap targets a transition to Nominated Proof of Stake "within roughly the next year," described as a planning estimate rather than a fixed date.

Staking is not a deposit. Since the dTAO upgrade in February 2025, each subnet has its own token, called alpha, paired with TAO in a weighted balancer pool. Staking sells TAO into that pool for alpha; unstaking sells alpha back. That makes price impact, slippage and swap fees part of every stake operation. The swap fee is the amount multiplied by a per-subnet rate, defaulting to roughly 0.05%, taken from the input side and paid to the block author. There is no unbonding period. Root-network staking is exempt: it converts one for one with no swap fee and no price impact.

A participant's stake weight on a subnet is its alpha staked there plus its root TAO stake scaled by a governance-set global factor, which was 0.18 on mainnet as of September 2026.

Supply and tokenomics

Halvings are not triggered by block counts. They fire when total issuance crosses the midpoint of the remaining supply.

Recycling complicates that curve in a useful way. Registration burns and transaction fees reduce total issuance, and recycled TAO can be re-emitted, which pushes halvings further out. Burned tokens, by contrast, stay counted in issuance forever. Total issuance is the yardstick for halvings; circulating supply is smaller, because issuance includes pool reserves and staked positions.

Each subnet's alpha token has its own 21 million cap and its own halving curve starting from that subnet's launch. Per block a subnet mints up to one alpha for participants plus alpha injected into its pool alongside the subnet's TAO emission. As a subnet matures the injection cap falls, and TAO that can no longer be injected is instead used to buy alpha on the subnet's own pool, which the documentation describes as a transition from liquidity injection to chain buybacks.

Emission is split across subnets by their exponential moving average prices, adjusted for miner incentive that was withheld, then passed through an emission gate that reduces weak shares. The base unit is rao: one TAO equals one billion rao.

History

Bittensor was developed with support from the Opentensor Foundation, which published the original open-source tools, SDK and documentation. The network's mainnet is called finney.

The most consequential change to date was dTAO, activated in February 2025 at block 4,920,351, which gave every subnet its own alpha token and converted existing stake to root TAO stake at the switch. Before dTAO, emission was allocated by root-network validator voting; afterwards it is allocated by market prices for subnet tokens. The first TAO halving followed in December 2025.

Development has since consolidated. The original Bittensor SDK repository is archived, with development moved into a subtensor monorepo that ships the chain, the Python SDK and the command-line tool together as Bittensor 11.

Risks and what to watch

The permissioned validator set is the clearest risk. A network marketed as decentralized intelligence currently runs its blockchain on proof of authority, with a privileged on-chain process able to change the authority set. The migration to Nominated Proof of Stake is a roadmap item, not a shipped feature, and roadmap timelines move.

Subnet token economics are the second. Alpha tokens are pool-priced against TAO, so their value depends on continued demand for staking into that subnet. Because staking is a swap, entering or exiting a thinly capitalized subnet at size moves the price against you, and the documentation is explicit that limit variants exist precisely because of mev and front running exposure on large swaps.

Third, incentive-mechanism risk. Subnet owners define how miners are scored. A poorly designed or captured mechanism can reward the wrong behaviour, and there is no protocol-level guarantee that a subnet's output is useful.

Finally, the halving schedule depends on issuance rather than time, and recycling changes it. Anyone modelling TAO supply from block counts alone will get the wrong answer.

Frequently asked questions

What is a subnet?

An independent incentive market identified by a number. Miners in it produce a digital commodity, validators score them, and the chain pays out TAO according to Yuma Consensus. Each subnet has its own token and its own rules.

Does Bittensor use proof of stake?

Not for block production, as of September 2026. The chain uses proof of authority with Aura and GRANDPA, with a documented plan to move to Nominated Proof of Stake. Yuma Consensus, which is stake-weighted, governs subnet rewards rather than block production.

How much TAO will ever exist?

21 million, with emission halving each time total issuance crosses the midpoint of the remaining supply. The first halving was in December 2025.

Is staking TAO risk-free?

No. Staking into a subnet is a swap into that subnet's alpha token, so the position's TAO value floats with the pool price. There is no unbonding period, but there is price impact on entry and exit.

Where can I buy Bittensor?

TAO is listed on a range of centralized venues. See where to buy Bittensor for availability where you live, and Exchanges for how those venues compare.