# Docs at the speed of light

Fern Docs are built from the ground up to be served instantly from the edge. They're the fastest docs we've tested, [averaging 92 in Lighthouse](https://buildwithfern.com/lp/fast-docs#lighthouse) (competitors average 73).

Faster docs on Fern: Cash App, Persona, ID.me, Square, ElevenLabs, Webflow.

## Why docs speed matters

Developers often read your docs on a phone or a slow connection while they decide whether to use your API. Most of the web is still slow there.

- **Most of the web is slow on phones.** Only 43% of mobile sites pass Google's Core Web Vitals, according to the HTTP Archive Web Almanac.
- **Speed counts in search.** Google's ranking systems use Core Web Vitals, so faster docs pages have a better chance of being found.
- **Fern Docs score in the top tier.** 11 of 17 Fern Docs sites we tested score 90 or above in mobile Lighthouse, the range Lighthouse rates good.

Sources: [HTTP Archive Web Almanac 2024](https://almanac.httparchive.org/en/2024/performance), [Google Search Central](https://developers.google.com/search/docs/appearance/core-web-vitals)

## Faster than other docs platforms

We ran mobile Lighthouse on 37 live docs sites. Only sites on Fern Docs scored above 90.

Want the methodology? [Read the engineering post](https://buildwithfern.com/post/static-docs).

## Fast for readers, simple for your team

- **Fast on any phone.** Fern Docs sites average 92 in mobile Lighthouse, even on an older phone over slow 4G.
- **Publish anytime.** Readers keep the current version until the new one is ready, so publishing never slows them down.
- **Keep every feature.** Search, Ask Fern, and login all work on static pages, and our team migrates you from your current platform within a week.

## More secure by default

Give your security team less to review. Every page ships with a strict Content Security Policy, so browsers block any script you didn't publish. And every asset loads from your own domain, so there are no third-party hosts to approve.

## Common questions about static docs

**What does it mean that Fern Docs sites are static?**
Every page is rendered ahead of time, when you publish, and served as finished HTML from the edge. Readers get the page as a file, not a render job, so there is no render delay.

**How fast are Fern Docs pages?**
We ran mobile Lighthouse on 37 live docs sites, on a simulated older Android phone over slow 4G. Fern Docs sites averaged 92, compared with 73 for sites on a competing docs product. 11 of 17 Fern Docs sites scored 90 or above, and none of the competitor's sites did.

**Do static pages limit what my docs can do?**
No. Search, Ask Fern, login, and every interactive feature work on static pages. They load as separate parts of the page, so they never hold up the rest of it.

**What happens for readers when I publish?**
Each publish builds a complete new version of your site. Readers keep getting the current version until the new one is fully ready, so no one waits on a slow page after an update.

**How do static pages help with security?**
Each page ships with a strict Content Security Policy that lists a fingerprint of every script it was built with, so browsers block anything else. All assets load from your own domain, so a network allowlist only needs your domain.

**Can I preview my docs locally?**
Yes. fern docs dev runs the same renderer that serves your readers. It starts in about 26 seconds, uses under 2 GB of memory, and reopens a page you've visited in 4 milliseconds.

**How long does it take to move to Fern?**
Our team migrates you from your current platform within a week. Every Fern Docs site is static, so your docs are fast from launch.

**How do I get started?**
Book a demo. A Fern engineer generates a preview of your docs from your API spec and walks you through it on the call.

## Five places docs sites get slow

- **Rendering:** Pages render on a server for each visit, so readers wait before anything appears. Fern: Every page is prebuilt when you publish and served as finished HTML.
- **Distance:** Pages come from one region, so readers far from it wait longer. Fern: Pages are served from the edge, close to every reader.
- **Publishing:** A new publish clears the cache, so the next readers get a slow page. Fern: Each publish builds a complete new version, and readers keep the current one until it's ready.
- **Interactive features:** Search, chat, and login scripts load first and hold up the page. Fern: Search, Ask Fern, and login load separately, so they never hold up the rest of the page.
- **Assets:** Fonts, images, and scripts load from other hosts, adding extra connections. Fern: Every asset loads from your own domain.

## Get started

- Book a demo: <https://buildwithfern.com/book-demo>
- Read the engineering post: <https://buildwithfern.com/post/static-docs>