Inheriting code nobody documented? Document it before the old team leaves

What goes wrong in a vendor switch

• The old vendor has little reason to write a good handover.
• The new team spends the first months reading code instead of delivering.
• Nobody on your side can say what the system really does, so you cannot check either vendor's claims.
• Every question becomes a paid support ticket to the partner you are leaving.

What you get instead

• What every endpoint does, in plain language, with the business rules it enforces.
• Step-by-step flows with the file and function behind each step.
• A data-access map: which endpoint reads or writes which table.
• Database schema, user journeys, flowcharts and sequence diagrams.
• Setup, environment variables, architecture and deployment notes.
• Export as Markdown, or sync to Notion, Confluence, GitHub Wiki, Azure DevOps Wiki, GitBook or SharePoint.

A transition plan that works

• Before notice is given: get repository access and run a scan. You now own a description of your own system.
• During the overlap: the new team reads the documentation first and uses the old vendor's time only for what the code cannot explain.
• After the switch: keep the repository connected. Every merged change updates the docs, so the knowledge stays with you, not with a supplier.

For the person responsible for the project

• You can answer how a feature works without asking a developer.
• You can compare what was billed with what changed, using the change entry for every merge.
• Onboarding the next developer, vendor or in-house hire takes days.
• You negotiate with suppliers from a position of knowing your own product.

Your code stays yours

Source code is cloned for the scan and deleted afterwards; it is never stored. Read-only access is enough. A self-hosted option is available for companies that keep everything in their own cloud.