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Architecture guide · 7 chapters · about 20 min

Frappe and ERPNext Architecture Guide

How Frappe and ERPNext work, read from the source at a tagged release: DocTypes, the document lifecycle, hooks, permissions, the scheduler, naming series and customising without forking.

Reviewed 14 Oct 2026For developers, ERP consultants and technical buyers

Checked against Frappe v16.52.0 and ERPNext v16.50.0; Frappe v15.123.0 and ERPNext v15.122.0 where they differ.

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The chapters, in order

The model

  1. What a DocType isOne definition that becomes a table, a form, an API and a permission set.3 min

What runs when

  1. What runs on save, submit and cancelEvery hook in order, and what it can still change.3 min
  2. hooks.py: changing Frappe without editing itWhat an app can set, how apps combine, and what a hook cannot do.2 min

Who can do what

  1. Roles, permissions and user permissionsFour checks on a document, a different path for a list.3 min

Time and numbers

  1. The scheduler and background jobsFrom hooks.py to a running job, and why one stays silent.3 min
  2. Naming series and the fiscal-year rolloverHow a name is picked, when the counter restarts, and which year you get.3 min

Changing it

  1. Custom field, custom app or forkWhat each choice stores, what an upgrade costs, and how to pick.3 min

Your next step

See it live

Run a sprint

Finish a task in this week's sprint, log the hour it took, and see the sprint's burndown, all on ERPNext's own records.

You end with hours booked on a task · 2 screens · about 3 min

See it liveAbout this flow

No sign-up, no card, no account.

Next step · Architecture guide

Now see how we build a Frappe app

A separate app in your own Git, so upgrades keep working.

Custom Frappe apps