ICP Canister Model

Canisters — Different by Design

Internet Computer (ICP, from DFINITY Foundation) uses 'canisters' as its core primitive. A canister is a WebAssembly module plus its persistent memory, run on a subnet of nodes. Unlike Ethereum smart contracts, a canister can: hold gigabytes of state directly, serve HTTP requests, make outbound HTTP calls, render web pages. ICP's marketing pitch is that you can run an entire app — backend, frontend, database — fully on-chain in canisters. Whether this is the right architectural choice is contested; the technology is genuinely different from anything else in the space.

Reverse Gas

ICP inverts the gas model: instead of users paying gas, canisters pay for their own computation via 'cycles' (ICP's gas equivalent). Users don't need crypto to interact with canisters — they just call the canister, which spends its own cycles to handle the request. The canister owner is responsible for keeping it funded. This makes user onboarding dramatically easier: no wallet, no gas, no first-deposit friction. The trade-off: canisters are essentially running their own infrastructure budget.

HTTP Outcalls and Direct Web Access

Canisters can make HTTP requests to external APIs (e.g., a weather API, a price feed, a partner system) with cryptographic consensus on the response. This is structurally different from oracle networks like Chainlink: ICP's HTTP outcall is built into the protocol rather than being a separate oracle layer. Multiple subnet nodes independently make the request; if they get different responses (e.g., the API is being attacked), the call fails. Production use cases include real-time financial data integration.

• Canisters combine compute + storage + HTTP serving in one primitive
• Reverse gas: canisters pay for their own computation; users pay nothing
• Native HTTP outcalls let canisters consume external APIs with consensus
• Genuinely different architecture from Ethereum-style smart contracts