> For the complete documentation index, see [llms.txt](https://developer.paddle.com/llms.txt).

# Store your own custom data against products and prices

Attach your own key-value data to products and prices in Paddle when working with the API.

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## What's new?

We updated [product](https://developer.paddle.com/api-reference/products/overview.md) and [price](https://developer.paddle.com/api-reference/prices/overview.md) entities so that now you can add `custom_data` when creating or updating them.

- **custom_data** (object): Your own structured key-value data

## How it works

[Custom data](https://developer.paddle.com/api-reference/about/custom-data.md) lets you add your own key-value data entities created using [Paddle Checkout](https://developer.paddle.com/concepts/sell/self-serve-checkout.md) or the API. Once added, you can see custom data in API responses and webhooks for an entity.

Previously, you could add custom data to [transaction](https://developer.paddle.com/api-reference/transactions/overview.md) and [subscription](https://developer.paddle.com/api-reference/subscriptions/overview.md) entities. Now you can add custom data to products and prices, too.

This is especially powerful because product and price entities are returned by [transaction previews](https://developer.paddle.com/api-reference/transactions/preview-transaction.md). This means you can store data, like a list of features or flags against your products, then use those on [pricing pages](https://developer.paddle.com/build/checkout/build-pricing-page.md) without needing to store that data yourself.

## Next steps

This change is available in version `1` of the Paddle API.

It's a non-breaking change, meaning it doesn't impact existing integrations.

You can work with [products](https://developer.paddle.com/api-reference/products/overview.md) and [prices](https://developer.paddle.com/api-reference/prices/overview.md) using the API to start adding `custom_data` to entities.
## Summary of changes

| Name | Type | Change | Entity | Description |
| --- | --- | --- | --- | --- |
| `custom_data` | Field | updated | Product | Now writable on create and update. |
| `custom_data` | Field | updated | Price | Now writable on create and update. |