The Plain Fetch viewer
In short
The viewer requests a URL the way a plain-fetch agent does: no JavaScript, one request for HTML, one for markdown, one for llms.txt and one for a path that should not exist. It shows the initial HTML on the left, the readable text on the right, and seven flags underneath.
Pre-loaded with www.wikipedia.org, read 4 November 2026. Type any public URL to run your own.
The page answers a plain fetch: 5 of 7 checks found.
Initial HTML what a plain fetch receives
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
[... 1 more head element folded ...]
<title>Scalar — API Documentation, SDKs & Hosted MCP Servers</title>
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<meta name="description" content="Scalar is the infrastructure layer between an API and the agents that use it. One OpenAPI document in; docs, SDKs, and a hosted MCP server out.">
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<meta name="robots" content="index, follow">
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<link rel="canonical" href="https://scalar.com">
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<link rel="alternate" type="application/rss+xml" href="https://scalar.com/resources/changelog/rss.xml">
</head>
<body class="scalar-app">
<script>[... 652 characters folded ...]</script>
<div id="app"><!--[--><div class="section-flare" data-v-585f91af><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div><div class="section-flare-item" data-v-585f91af></div></div><main class="content content-header content-sidebar" data-v-585f91af><div class="page-content" data-v-585f91af><div class="page-layout" hasmath="false" data-v-e0135ec5><!----><div class="page-body" data-v-e0135ec5><div class="page page--docs-page t-editor" data-v-e0135ec5><div class="content" data-v-e0135ec5><!----><div data-v-e0135ec5><div class="page-node t-prose">
<section class="hl-hero" data-hl-hero="" data-hl-mode="docs">
<div class="hl-stage" aria-hidden="true" data-md-exclude="">
<canvas class="hl-canvas" data-hl-canvas=""></canvas>
</div>
<div class="hl-copy">
<h1 id="infrastructure-for-apis-in-the-age-of-agents." class="scroll-pad interaction-observer-heading t-editor__heading" data-level="1" data-scalar-type="heading">
Infrastructure for APIs in the age of agents.
<button class="notify-container" aria-label="Copy link to heading"><svg xmlns="http://www.w3.org/2000/svg" fill="currentColor" viewBox="0 0 256 256" aria-hidden="true" class="icon notify">[... 153 characters folded ...]</svg>
<svg xmlns="http://www.w3.org/2000/svg" fill="currentColor" viewBox="0 0 256 256" aria-hidden="true" class="icon">[... 450 characters folded ...]</svg></button>
</h1>
<p class="t-editor__paragraph">From an agent's first read of your docs to its millionth production call, Scalar is the layer in between: hosted, observed, and kept in sync from one OpenAPI document.</p>
<div class="hl-cta flex gap-2">
<a href="https://dashboard.scalar.com/register" class="t-editor__button hl-pill t-editor__anchor">Get Started</a>
<button type="button" class="hl-pill lp-onboard" data-lp-onboard="" data-md-exclude="" aria-label="Onboard your agent: copy the Scalar setup prompt"><span class="lp-onboard-agents" aria-hidden="true"><span class="lp-onboard-agent"><svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">[... 1,580 characters folded ...]</svg></span><span class="lp-onboard-agent"><svg fill="currentColor" fill-rule="evenodd" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">[... 1,531 characters folded ...]</svg></span><span class="lp-onboard-agent"><svg fill="currentColor" fill-rule="evenodd" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">[... 391 characters folded ...]</svg></span></span><span class="lp-onboard-text" aria-live="polite"><span class="lp-onboard-rest">Onboard your agent</span><span class="lp-onboard-done">Paste to your agent</span></span><span class="lp-onboard-icon" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" class="t-editor__icon lp-onboard-copy">[... 221 characters folded ...]</svg><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" class="t-editor__icon lp-onboard-check">[... 157 characters folded ...]</svg></span></button>
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</div>
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</div>
</section>
<div class="hl-essay">
<h2 id="one-openapi-document-in.-docs-mcp-and-sdks-out." class="scroll-pad interaction-observer-heading t-editor__heading" data-level="2" data-scalar-type="heading">
One OpenAPI document in. Docs, MCP, and SDKs out.
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</h2>
<p class="t-editor__paragraph">For two decades the interface was the product. Now people ask a chat box, and an agent calls your API for them. Scalar builds what that agent needs.</p>
</div>
<div class="hl-row-card" data-md-exclude="">
<div class="dh-hero hl-row" data-dh-contained="true" data-md-exclude="">
<div class="dh-field" aria-hidden="true"><span class="dh-face" data-left="/headless-row/supabase-docs" data-right="/headless-row/supabase-claude" data-prompt="Create a Supabase project called acme in us-east-1"></span><span class="dh-face" data-left="/headless-row/linear" data-right="/headless-row/linear-claude" data-prompt="What's still open for Thursday's API release?"></span><span class="dh-face" data-left="/headless-row/superhuman" data-right="/headless-row/superhuman-claude" data-prompt="Which emails need a reply from me today?"></span><span class="dh-face" data-left="/headless-row/zoom-docs" data-right="/headless-row/zoom-claude" data-prompt="Delete the archived files from yesterday's all-hands"></span><span class="dh-face" data-left="/headless-row/gcal" data-right="/headless-row/gcal-claude" data-prompt="Find 30 minutes with Dana and Priya on Thursday afternoon"></span>
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Shown with 105 long blocks (scripts, styles, long tags) folded into a marker that says how many characters they hide; the pane stops after the first 200 words; the page is 334 KB.
Reading view the text a plain-fetch client can extract
title: Scalar — API Documentation, SDKs & Hosted MCP Servers
Infrastructure for APIs in the age of agents.
Infrastructure for APIs in the age of agents. From an agent's first read of your docs to its millionth production call, Scalar is the layer in between: hosted, observed, and kept in sync from one OpenAPI document. Get Started Onboard your agentPaste to your agent One OpenAPI document in. Docs, MCP, and SDKs out. For two decades the interface was the product. Now people ask a chat box, and an agent calls your API for them. Scalar builds what that agent needs. Write a message… Fable 5.1 Docs to read Your guides and API reference on one site, under your own domain and theme, with access groups for partner portals. Every page is also served as Markdown, alongside an llms.txt and a Docs MCP endpoint, so agents read what your developers read. The core is open source, with 16k GitHub stars. Learn more → An MCP server to call Scalar turns your OpenAPI document into a hosted MCP server, so Claude or ChatGPT can use your API directly. It exposes a small, fixed set of tools and fetches operation details on demand, so any API fits in about 0.2% of context. Learn more → MCP & Agent Connect your APIs
436 more words follow in the initial HTML.
| Check | Result | Detail |
|---|---|---|
| H1 in the initial HTML | Found one H1 | First H1: Infrastructure for APIs in the age of agents. |
| First 200 words in the initial HTML | Found 200 of 200 words | The initial HTML carries 636 words of visible text; the first 200 are marked in the left pane. |
| llms.txt present and linked | Note present, not linked | 77597 bytes, 394 links. Structure grade A (6 of 6). Nothing on the home page points to it. Ora's lab found 86 percent of llms.txt fetches arrived through a link. |
| Markdown on request | Found text/markdown | Accept: text/markdown returned 200 with text/markdown; charset=utf-8. Vary: Accept is set. |
| Status of a made-up path | Found 404 | /agent-ready-html-missing-path-check returned 404: a real status code for a missing page. |
| JSON-LD types | Missing none | No JSON-LD block on the home page. Ora's lab found it made no difference when the answer was already in the HTML; Google says it is not needed for AI features. |
| OpenAPI link | Found linked | The home page links an OpenAPI file. 97 percent of openapi.json fetches in Ora's lab arrived through a link. |
Run the full check
The viewer read one page with four requests. The full check we recommend next is Ora's scan. Its Access layer runs 42 checks worth 30 of its 100 points, among them content without JavaScript, bot detection, llms.txt, markdown on request, JSON-LD and the sitemap (Ora's check catalogue, contract 1.38.0, read 5 November 2026). Open Ora's report for scalar.com.
Limits: Ora reads public URLs only, says two runs of one scan land within a couple of points without publishing repeat-scan data, and keeps the product that fixes what it finds behind a waitlist. Cloudflare's scanner at isitagentready.com is a quick free alternative, and Mintlify's score covers documentation.
What the viewer does
It sends four plain GET requests with the user agent Mozilla/5.0 (compatible; agent-readiness-crawl/1.0): the URL itself, the same URL with Accept: text/markdown, /llms.txt on the same host, and a made-up path at the root. It runs no JavaScript. The left pane is the first bytes of the HTML as text, with long scripts and styles folded into a marker that says how many characters they hide. The H1 and the first 200 words of visible text are marked in both panes. The flags under the panes say what the four responses added up to.
Limits
- Ten seconds for all four requests together, 1.5 MB read from the home page, at most five redirects, each one checked again.
- http and https only, default ports only. Private, local and internal addresses and names are refused.
- Ten runs per address per minute. The counter lives in memory on the edge function, so it is per instance rather than global. Past ten you get a 429 with a Retry-After header.
- Results are cached for 24 hours by the response headers. Nothing is written to a database: the viewer keeps the first 200 words and the extracted fields for the length of the request and keeps no page body beyond that.
What it does not tell you
A plain fetch from this server is not a real agent. Bot protection weighs the source address more than the user agent, so a page that answers 200 here can still refuse an agent, and the reverse. Ora's lab found (2026-10-19) that returning 403 to agent user agents and hiding the answer in JavaScript were the only two of 19 configurations that stopped retrieval; the viewer can see the second, and can only hint at the first. The initial HTML reference covers both. The server logs and the published crawler address ranges settle the first.
The seven flags
- H1 in the initial HTML
- Whether the HTML the server sends already contains an H1. It is the cheapest sign that the page does not depend on scripts to say what it is.
- First 200 words in the initial HTML
- Whether at least 200 words of visible text arrive in the initial HTML. Under 40 words with an app root element is flagged as a JavaScript shell.
- llms.txt present and linked
- Whether /llms.txt answers with a plain-text file, whether the home page links it (an anchor, a link element or a Link header), and the structure grade the index uses.
- Markdown on request
- Whether a request with Accept: text/markdown comes back as text/markdown. Cloudflare Radar found 3.9 percent of scanned top sites passing this at its April 2026 launch.
- Status of a made-up path
- Whether a path that should not exist returns 404 or 410. A 200 is a soft 404 and reads as a live page.
- JSON-LD types
- The schema.org types found in JSON-LD blocks on the page. Ora's lab found JSON-LD made no difference when the answer was already in the HTML.
- OpenAPI link
- Whether the page links an OpenAPI file, by an anchor or a service-desc link relation. It matters only for a site that ships an API.
Sources
- Ora: AgentReady launch post (Ora's lab findings) https://ora.ai/blog/agentready-launch, read 4 November 2026
- Ora check catalogue, contract 1.38.0 (132 checks, 42 in the Access layer) https://ora.ai/api/checks, read 5 November 2026
- Ora home page (the fixing product is behind a waitlist) https://ora.ai/, read 5 November 2026
- Ora: Introducing Deep Scan (repeat scans) https://ora.ai/blog/introducing-deep-scan, read 5 November 2026
- Ora llms.txt (public URLs only) https://ora.ai/llms.txt, read 5 November 2026
- Vercel: Make your site readable by AI agents https://vercel.com/kb/guide/make-your-site-readable-by-ai-agents, read 4 November 2026
- llms.txt proposal (llmstxt.org) https://llmstxt.org/, read 4 November 2026
Last reviewed 5 November 2026