---
title: Response headers
description: The _headers file, why it exists, and where it has to live.
---

Reed writes a `_headers` file into every build:

```
/*.md
  Content-Type: text/markdown; charset=utf-8

/llms.txt
  Content-Type: text/plain; charset=utf-8

/*/llms.txt
  Content-Type: text/plain; charset=utf-8
```

## Why it exists

Static hosts guess content types from file extensions, and most guess wrong for `.md` —
commonly `application/octet-stream`, which makes a browser download the file rather than
render it. The markdown mirrors and `llms.txt` are the machine-readable half of your
documentation; served as a binary download they are close to useless.

## It belongs at the root of the served tree

Cloudflare Pages and Netlify read `_headers` from the **top of the served directory**, and
its rules match served URL paths.

If your site is mounted under a path, this creates a split that is easy to get wrong:

```
served-root/
  docs/           ← the contents of dist/
    index.html
    llms.txt
  _headers        ← stays HERE, not inside docs/
```

The `/*/llms.txt` rule in the emitted file is what covers the mounted case — it matches
`llms.txt` one directory down, which is where a based site's copy actually lives.

## Hosts that do not read it

`_headers` is a Cloudflare Pages and Netlify convention. Other hosts need the equivalent
expressed their own way:

- **nginx** — a `types` block or `location` with `add_header`
- **S3 + CloudFront** — `Content-Type` metadata set per object at upload
- **Vercel** — a `headers` entry in `vercel.json`

Reed emits the file it can emit. Translating it is your host's business, and skipping the
translation costs you the markdown surfaces rather than the site.

## Verifying

Check the served content type rather than the file's presence:

```sh
curl -s -o /dev/null -w "%{content_type}\n" https://docs.example.com/llms.txt
```

Expect `text/plain`. Getting `application/octet-stream` means the rules are not being
applied — most often because `_headers` ended up inside the mount directory instead of at
the root.