| Current default Bun version |
| --- |
| **`1.4.2`**<br>Services created before **2026-09-09** have a different default version. [See below](/content/docs/bun-version#history-of-default-bun-versions/index.html). |

**To include Bun in your service's environment, you must do _at least one_ of the following:**

- Set your service's Bun version using one of the methods below.
- Include a `bun.lock` or `bun.lockb` file in your service's root directory.

Otherwise, your service's environment will _not_ include Bun.

**Set your service's Bun version in any of the following ways** (in descending order of precedence):

1. Set the `BUN_VERSION` environment variable for your service in the [Render Dashboard](https://dashboard.render.com/):

2. Add a file named `.bun-version` to the root of your repo. This file contains a single line with the version to use:

```bash
.bun-version
```

```
1.4.2
```

You can specify either a semantic version number (such as `1.3.4`) or use `latest` to always use the most recent version of Bun with every deploy.

## History of default Bun versions

If you don't set a Bun version for your service, Render's default version depends on when you originally created the service:

| Service Creation Date | Default Bun Version |
| --- | --- |
| `2026-09-09` and later | `1.4.2` |
| `2026-07-16` to `2026-09-09` | `1.3.14` |
| `2025-12-08` to `2026-07-16` | `1.3.4` |
| `2025-08-18` to `2025-12-08` | `1.2.20` |
| Before `2025-08-18` | `1.1.0` |