> ## Documentation Index
> Fetch the complete documentation index at: https://stripe-invoice-custom-fields-docs.vinaka-apps.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> What the Invoice Custom Fields app does and when to use it.

The Invoice Custom Fields app automatically fills in custom fields on your Stripe invoices using values from invoice metadata, subscription metadata, Checkout custom fields, customer metadata, or static fallbacks.

At a high level:

* you configure up to 4 field mapping rules in the app settings,
* the app fills draft invoices automatically as Stripe creates them,
* subscription renewals carry their custom field values forward via subscription metadata,
* the invoice drawer shows you exactly which value the app used for each field, and where it came from.

## Who this app is for

This app is for teams that use **Stripe Invoicing** and need custom fields (like PO numbers, project codes, customer references, or cost centers) automatically populated on invoices — including invoices generated by subscriptions or by Stripe Checkout.

## How the source priority works

Each rule resolves a value from the highest-priority source that has data, in this order:

1. **Invoice metadata**
2. **Subscription metadata** / **Checkout custom fields**
3. **Customer metadata**
4. **Static fallback** configured on the rule

The first non-empty match wins. The drawer on each invoice shows you which tier produced the value.

## Optional: save mapped values as invoice metadata

A separate toggle lets the app also write the resolved values into the invoice's metadata. Useful for downstream exports, integrations, and reports — metadata is searchable via the Stripe API. Existing metadata keys are never overwritten.

## Data handling summary

* Configuration is stored per Stripe account in our database.
* The app reads invoice, subscription, customer, and Checkout metadata from Stripe to resolve values.
* The app writes back custom fields (and optionally metadata) onto invoices, and writes subscription metadata so renewal invoices auto-fill.
* No sensitive customer data is stored beyond operational references.

For exact details, see:

* [Privacy Policy](/legal/privacy-policy)
* [Terms & Conditions](/legal/terms-conditions)

## Continue

<CardGroup cols={2}>
  <Card title="Install the app" icon="download" href="/getting-started/installation">
    Step-by-step install and first setup.
  </Card>

  <Card title="Configure field mappings" icon="gear-complex" href="/getting-started/configuration">
    Set up your invoice custom field rules.
  </Card>

  <Card title="Use the app" icon="book" href="/using-the-app/app-manual">
    Learn how the app fills invoices automatically and how Payment Links work.
  </Card>

  <Card title="Troubleshooting" icon="circle-question" href="/using-the-app/faq">
    Fix common setup and sync issues quickly.
  </Card>
</CardGroup>