This onboarding checklist was shared by Nat Pryce, and is a checklist of topics that new hires need to know to work on an application called OPA. If you create and share a checklist like this for people joining your project, ask them to keep track of where they found answers and how long it took so that you can improve it for the next person.
Major architectural components. Which are part of OPA and which are shared across CA (the larger product family)?
Code structure and naming conventions: naming, package locations, where different things live, etc.
Error handling strategy; results vs. exceptions.
Testing strategy: automated vs. exploratory testing, testing across integration points with legacy systems.
How to run the application locally.
Business context: what part of the business does OPA support, and the upstream/downstream business processes.
Coding style: options vs. nulls, strong types vs. strings, no reflection, etc.
Project history: why did it get this way?
Technical context: which systems do we integrate with, either within the company or external systems.
Logging and monitoring.
Lifecycle of changes: from ideas through cards on the board to live.
The preserve/expand/contract process for zero-downtime deployment, both technically and how that relates to stories and cards on the board.
Technical toolset: Jira/Kotlin/IntelliJ/ELK/Grafana/Casperpass etc.
Environments (local, staging, live) and what they are used for.
Which Slack channels and email lists to join.
Which services are live on OPA?
The user journey from article submission to OPA and payment.