Every change to a prompt in the Prompt Library creates a new immutable version, numbered
sequentially as `v1`, `v2`, `v3`, … Once created, a version can't be modified — you always have
a full audit trail.

You can create new versions from the Opik UI or from code using the SDK.

## Creating a new version

::::tabs
:::tab{title="Opik UI"}
To create a new version from the Opik platform:

1. Navigate to the **Prompt Library** for your project
2. Open the prompt you want to edit
3. Click **Edit** and update the template
4. Click **Create new version**

The new version is available immediately.
:::

:::tab{title="Python SDK"}
Call `create_prompt` (or `create_chat_prompt`) again with the same `name` and the updated
template — the SDK creates the next sequential version automatically:

```python
import opik

client = opik.Opik()

# v1
client.create_prompt(
    name="system_prompt",
    prompt="You are a helpful assistant.",
    project_name="my-agent",
)

# v2
client.create_prompt(
    name="system_prompt",
    prompt="You are a coding assistant specializing in {{language}}.",
    project_name="my-agent",
)
```

If the template is identical to the latest version, no new version is created.
:::

:::tab{title="TypeScript SDK"}
Call `createPrompt` (or `createChatPrompt`) again with the same `name` and the updated
template — the SDK creates the next sequential version automatically:

```ts
import { Opik } from "opik";

const client = new Opik();

// v1
await client.createPrompt({
  name: "system_prompt",
  prompt: "You are a helpful assistant.",
  projectName: "my-agent",
});

// v2
await client.createPrompt({
  name: "system_prompt",
  prompt: "You are a coding assistant specializing in {{language}}.",
  projectName: "my-agent",
});
```

If the template is identical to the latest version, no new version is created.
:::
::::

## Fetching a specific version

Pass the `version` parameter to fetch a specific version, or omit it to fetch the most recent:

:::code-group
```python title="Python"
import opik

client = opik.Opik()

# Fetch a specific version
v3 = client.get_prompt(name="system_prompt", version="v3", project_name="my-agent")

# Fetch the most recent version (omit `version`)
latest = client.get_prompt(name="system_prompt", project_name="my-agent")
```

```ts title="TypeScript"
import { Opik } from "opik";

const client = new Opik();

// Fetch a specific version
const v3 = await client.getPrompt({
  name: "system_prompt",
  version: "v3",
  projectName: "my-agent",
});

// Fetch the most recent version (omit `version`)
const latest = await client.getPrompt({
  name: "system_prompt",
  projectName: "my-agent",
});
```
:::

## Comparing versions

You can compare any two versions side-by-side in the Opik UI to see exactly what changed. This is
useful for reviewing changes before pointing your agent at a new version.

:::frame
<img src="../img/apps/opik-documentation/documentation/fern/img/v2/prompt-library/prompt-versions.png" alt="Version comparison view showing a diff of prompt changes between two versions">
:::

## Related pages

- [Prompt Library Overview](./development-prompt-engineering-overview.md)
- [Getting started with the Prompt Library](./development-prompt-engineering-getting-started.md)
- [Text and chat prompts](./development-prompt-engineering-prompt-types.md)

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