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Created by Chainlink Labs

Custom Data Feed

A template for bringing your own custom off-chain data feed on-chain with the Chainlink Runtime Environment (CRE).

View on GitHub
TypeScript
Go

This template provides an end-to-end starting point for bringing your own custom data feed on-chain with the Chainlink Runtime Environment (CRE). It showcases local simulation and the core CRE workflow patterns.

What This Template Does Components:

  • Contracts (Solidity) under projectRoot/contracts/evm/src: ReserveManager, SimpleERC20, BalanceReader, MessageEmitter
  • CRE Workflow that fetches your off-chain data and optionally performs chain writes based on configurable triggers (cron or EVM log).

Key Technologies:

  • CRE (Chainlink Runtime Environment) – orchestrates workflows with DON consensus.

TypeScript: Update .env (private key), install dependencies (bun install --cwd ./my-workflow), configure RPC in project.yaml, deploy contracts, configure config.json and workflow.yaml, run cre workflow simulate.

Go: Update .env, configure RPC in project.yaml, deploy contracts, run cre generate-bindings evm, edit config.json and workflow.yaml, run cre workflow simulate my-workflow.

Pre-deployed addresses on Ethereum Sepolia: ReserveManager, SimpleERC20, BalanceReader, MessageEmitter (see README).

Security Considerations

  • Demo project – Not production-ready.
  • Demo contracts – Not audited; do not use as-is in production.
  • Use your own RPCs – For stability and performance, prefer private RPCs for deployment and chain writes.
  • Secrets hygiene – Keep real secrets out of version control; use secure secret managers for .env values.

Install the CRE CLI to use this template

You can use the command below or download the latest CLI release on GitHub.

curl -sSL https://cre.chain.link/install.sh | bash
Author
Chainlink Labs
LicenseMIT

Disclaimer

This template represents an educational example to use a Chainlink system, product, or service and is provided to demonstrate how to interact with Chainlink's systems, products, and services to integrate them into your own. This template is provided "AS IS" and "AS AVAILABLE" without warranties of any kind, it has not been audited, and it may be missing key checks or error handling to make the usage of the system, product or service more clear. Do not use this example in a production environment without completing your own audits and application of best practices. Neither Chainlink Labs, the Chainlink Foundation, nor Chainlink node operators are responsible for unintended outputs that are generated due to errors in code.