What Does It Mean to Rent Blockspace on Polkadot, and Who's Doing It?

Renting blockspace on Polkadot means paying in $DOT to reserve processing time on the network's shared validator set, called a core, either in a fixed monthly block or in single-block increments, instead of locking up tokens for years to win a permanent slot. This system is called Agile Coretime, and it replaced Polkadot's old parachain slot auctions in 2024. Projects like Astar, Hydration, and Acala are among those using it today. What Is Coretime on Polkadot? Coretime is the name for the resource Polkadot sells. In Polkadot's architecture, a core is a unit of computing power that the Relay Chain, Polkadot's base layer, provides to validate blocks for a connected chain called a parachain. Think of a core as a processing slot. Not every parachain needs a full core running constantly, so coretime allows a parachain to rent a fraction of a core, such as one-tenth, or rent several cores if it needs more power. Worth noting, Polkadot's old model was rigid. Under the original parachain slot auction system, a team had to win an auction and lock up large amounts of DOT for up to two years to secure a slot. That slot ran constantly, whether the chain was busy or nearly empty. Small teams were priced out, and budgets depended on DOT's market price at auction time, adding financial risk unrelated to the actual engineering work. Bulk Coretime Versus On-Demand Coretime Agile Coretime gives developers two main ways to rent blockspace. Bulk coretime is a fixed block of continuous coretime, currently set at 28 days, represented as an NFT that can be purchased through coretime sales, then split, shared, or resold. Teams with steady, predictable traffic tend to buy bulk coretime because it comes with a price-capped renewal option, which helps them plan costs ahead of time. On-demand coretime lets a parachain pay in DOT per block, drawing from cores set aside specifically for this purpose. This suits chains with unpredictable or spiky usage that don't want to commit to a full month. A parachain can also combine both approaches, using bulk coretime for its baseline needs and on-demand coretime to handle traffic spikes. Why Did Polkadot Move Away from Slot Auctions? Polkadot's governance approved the switch to Agile Coretime because the auction model created a real barrier to entry. Winning a slot required locking up DOT for a fixed lease term, often with the help of a crowdloan, an arrangement where community members lent DOT to a project in exchange for that project's own tokens. This process worked, but it concentrated blockspace access among teams with enough capital and community backing to win an auction, regardless of whether they actually needed constant block production.