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Blockchain Smart Contracts with Solidity · Lesson

Building Custom Oracle Contracts

Learn how to design and implement your own oracle pattern in Solidity, including request-response flows, trusted updaters, and validating data freshness on-chain.

Beyond Third-Party Oracles

Chainlink and similar networks cover common feeds, but sometimes you need data nobody else provides, like a proprietary API result. In those cases you build a custom oracle: an off-chain updater plus an on-chain contract that stores and serves the data.

The Two-Party Design

A custom oracle has two sides:

  • Off-chain updater: a server that reads the external source and sends transactions.
  • On-chain contract: stores the latest value and exposes a read function for other contracts.

All lessons in this course

  1. The Oracle Problem Explained
  2. Integrating Chainlink Oracles
  3. Handling Off-chain Data Retrieval
  4. Building Custom Oracle Contracts
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