Snowflake SDK lets you schedule an on-chain cron job in just 2 lines of code.
The SDK is open sourced. You can learn more about it here: https://github.com/snowflake-so/snowflake-sdk
SDK Intro on our Medium blog: https://medium.com/@snowflake_so/solana-on-chain-cron-scheduler-is-here-7839b7d67c0