Scalar against Fern on what an agent reads
In short
The Scalar llms.txt starts with an H1 and blockquote summary, then H2 sections that mirror the navigation groups, linking .md URLs. Fern leads on content in the initial HTML, 2 to 1; Scalar: Docs pages are served as HTML; the API reference component renders in the browser in some embeds.
The sourced difference
Scalar leaves hidden pages out of llms.txt and llms-full.txt; Fern leaves pages that fall back to default-language content out of locale indexes and serves custom llms.txt for the default locale only. Source, read 4 November 2026.
The rubric side by side
| Key | Scalar | Fern |
|---|---|---|
| Content in the initial HTML | 1, with setup | 2, on by default |
| Real status codes | 2, on by default | 2, on by default |
| llms.txt generation | 2, on by default | 2, on by default |
| llms.txt linking | 1, with setup | 2, on by default |
| Markdown on request | 1, with setup | 2, on by default |
| JSON-LD output | 0, not offered | 0, not offered |
| OpenAPI exposure | 2, on by default | 2, on by default |
| Fenced, tagged code | 2, on by default | 2, on by default |
| Total | 11 of 16 | 14 of 16 |
The two differ on 3 of the numeric keys: content in the initial HTML, llms.txt linking, markdown on request. Evidence for each score is on the profiles of Scalar and Fern.
Verdicts by reader
- Technical SEO
- Both keep the index in step with what humans can see.
- Docs owner
- Fern handles localized docs; Scalar keeps one index.
- Front-end developer
- Neither needs code for the files.
What each leaves undone
Scalar
- Does not let users author the generated llms.txt on hosted Scalar Docs.
- Does not include hidden pages.
Fern
- Does not give individual pages their own llms.txt.
- Does not serve custom llms.txt files for non-default locales.
Work left to the developer: Scalar, Low on hosted Scalar Docs; medium for self-hosted API references, which need their own llms.txt route. Fern, Low: write frontmatter descriptions; use llms-only and llms-ignore controls where needed.
Sources
- buildwithfern.com: the difference https://buildwithfern.com/learn/docs/ai-features/llms-txt, read 4 November 2026
- Scalar: documentation https://scalar.com/products/docs/configuration/llms-txt, read 4 November 2026
- Fern: documentation https://buildwithfern.com/learn/docs/changelog, read 4 November 2026
Last reviewed 4 November 2026