What Is the Difference between an On-Chain and Off-Chain Data Source for an Oracle?

An off-chain data source is any data existing outside the blockchain, such as a price from a CEX or a weather API. An on-chain data source is information already present on the blockchain itself, like the token balance of a wallet or the transaction history of a DEX.

Oracles primarily focus on bridging the gap for off-chain data. However, an on-chain source can still be manipulated if it is a low-liquidity DEX pool, which is then incorrectly used as the single price feed.

Does a CEX Utilize a Mempool Concept, and If So, How Is It Different from a Blockchain Mempool?
How Does the ‘Settlement’ Process Differ between a CEX and a DEX for an Option Contract?
How Do Exchange API Limits Affect the Speed of Liquidation Engines?
What Role Do API Rate Limits Play in Reducing the Risk of Market Manipulation?
What Role Does an Exchange’s API Play in Soft Liquidation Strategies?
How Does the Execution of a Limit Order Differ on a CEX versus a DEX?
How Does a Decentralized Exchange (DEX) Differ from a Centralized Exchange (CEX) in Risk Profile?
What Is an API, and Why Is Its Reliability Critical for Financial Settlements?

Glossar