---
title: "Versioning for API Methods"
source_url: https://docs.rapyd.net/en/versioning-for-api-methods.html
lang: en
---

# Versioning for API Methods

Dated versions are used for breaking changes and selected new features.

Some individual API methods have a dated version. Select the version you want as follows:

- To use the dated version, you must specify the date in the `api_version` header parameter in **yyyy-mm-dd** format. For example: **2023-11-29**.
- To use an API method without a dated version, omit the `api_version` header parameter.

Versioning of an API method might affect the following:

- REST request or response
- Webhooks
- Behavior or business logic

## Nonbreaking Changes

The following changes are generally considered nonbreaking and backward-compatible:

- New method or endpoint.
- New optional parameter or field in header, request body, response or webhook.
- New value in list of values, larger range for a numeric parameter, longer length for a string parameter.
- Required parameter changed to optional.
- New default value for a parameter.
- New error code and message, or updated error message.
- New webhook.

## Breaking Changes

The following changes are generally considered breaking and might adversely impact clients' code:

- Deleted endpoint.
- Deleted parameter or changed parameter name in REST request, REST response or webhook.
- New required parameter or optional parameter changed to required.
- Value deleted from list of values, smaller range for a numeric parameter, shorter length for a string parameter.
- Parameter datatype changed.
- Changed error code.
- Materially different behavior due to a new value in a list of values or other cause that affects the use or functionality of the API.