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api/versioning.md

Changed on 2026-08-12 12:52:13 EST

+4 lines added
-3 lines removed
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# Versions¶

---¶
title: Versions¶
url: https://platform.claude.com/docs/en/api/versioning¶
description: "When making API requests, you must send an `anthropic-version` request header. For example, `anthropic-version: 2023-06-01`. If you are using the [client SDKs](https://platform.claude.com/docs/en/cli-sdks-libraries/overview), this is handled for you automatically.
"
---¶

For any given version with the Messages API, Anthropic preserves:¶

* Existing input parameters¶
* Existing output parameters¶

However, Anthropic may do the following:¶

* Add additional optional inputs¶
* Add additional values to the output¶
* Change conditions for specific error types¶
* Add new variants to enum-like output values (for example, streaming event types)¶

Generally, if you are using the API as documented in this reference, Anthropic will not break your usage.¶

## Version history¶

Anthropic recommends using the latest API version whenever possible. Previous versions are considered deprecated and may be unavailable for new users.¶

* `2023-06-01`¶

* New format for [streaming](https://platform.claude.com/docs/en/build-with-claude/streaming) server-sent events (SSE):¶

* Completions are incremental. For example, `" Hello"`, `" my"`, `" name"`, `" is"`, `" Claude." `instead of `" Hello"`, `" Hello my"`, `" Hello my name"`, `" Hello my name is"`, `" Hello my name is Claude."`.¶
* All events are [named events](https://developer.mozilla.org/en-US/Web/API/Server-sent%5Fevents/Using%5Fserver-sent%5Fevents#named%5Fevents), rather than [data-only events](https://developer.mozilla.org/en-US/Web/API/Server-sent%5Fevents/Using%5Fserver-sent%5Fevents#data-only%5Fmessages).¶
* Removed unnecessary `data: [DONE]` event.¶

* Removed legacy `exception` and `truncated` values in responses.¶

* `2023-01-01`: Initial release.¶

Unified Diff

--- a/api/versioning.md
+++ b/api/versioning.md
@@ -1,7 +1,7 @@
-# Versions
-
-When making API requests, you must send an `anthropic-version` request header. For example, `anthropic-version: 2023-06-01`. If you are using the [client SDKs](/docs/en/cli-sdks-libraries/overview), this is handled for you automatically.
-
+---
+title: Versions
+url: https://platform.claude.com/docs/en/api/versioning
+description: "When making API requests, you must send an `anthropic-version` request header. For example, `anthropic-version: 2023-06-01`. If you are using the [client SDKs](https://platform.claude.com/docs/en/cli-sdks-libraries/overview), this is handled for you automatically."
 ---
 
 For any given version with the Messages API, Anthropic preserves:
@@ -24,7 +24,7 @@
 
 * `2023-06-01`
 
-  * New format for [streaming](/docs/en/build-with-claude/streaming) server-sent events (SSE):
+  * New format for [streaming](https://platform.claude.com/docs/en/build-with-claude/streaming) server-sent events (SSE):
 
     * Completions are incremental. For example, `" Hello"`, `" my"`, `" name"`, `" is"`, `" Claude." `instead of `" Hello"`, `" Hello my"`, `" Hello my name"`, `" Hello my name is"`, `" Hello my name is Claude."`.
     * All events are [named events](https://developer.mozilla.org/en-US/Web/API/Server-sent%5Fevents/Using%5Fserver-sent%5Fevents#named%5Fevents), rather than [data-only events](https://developer.mozilla.org/en-US/Web/API/Server-sent%5Fevents/Using%5Fserver-sent%5Fevents#data-only%5Fmessages).