duolingo.com

Whether agents can crawl you, find you in the registries and searches they check, and trust what they find.

• ◐Sitemap present & freshrequired2/4

  Sitemap at https://www.duolingo.com/sitemap_index.xml is valid XML with 44 entries but contains no <lastmod> dates

  fix → Publish /sitemap.xml, reference it from robots.txt, and include <lastmod> dates so agents can tell what's current. Freshest lastmod seen: none.

  Resolved the sitemap from robots.txt or /sitemap.xml, validated XML, and checked lastmod freshness

  spec ↗report issue
• ✓Brand search discoverabilityrequired4/4

  Both searches ("Duolingo" and "Duolingo education") cited duolingo.com: https://blog.duolingo.com/video-call-research-report/, https://www.duolingo.com/efficacy

  Ran clean brand-name web searches and checked whether your domain is cited in the results

  report issue
• —MCP registry listingsrecommendedna

  No MCP server detected for this product

  Queried the official MCP registry, Smithery, Glama, and PulseMCP for servers matching your domain

  spec ↗report issue

Whether your robots policy, bot protection, and agent guidance actively admit AI agents instead of blocking them.

• ✓robots.txt present & parseablerequired2/2

  /robots.txt parses: 3 User-agent group(s), 1 Sitemap line(s)

  Fetched /robots.txt and validated it parses as a robots policy

  spec ↗report issue
• ✓AI crawler policyrequired5/5

  All 12 AI crawler user-agents (GPTBot, ClaudeBot, PerplexityBot, …) are allowed at / by robots.txt

  Evaluated robots.txt groups for the major AI agent user-agents (GPTBot, ClaudeBot, PerplexityBot, …)

  report issue
• ✗Content Signals directivesemerging0/2

  No Content-Signal lines in robots.txt

  fix → Declare Content Signals in robots.txt (e.g. `Content-Signal: search=yes, ai-train=no`) to express AI usage preferences machine-readably.

  Looked for Content-Signal lines in robots.txt

  spec ↗report issue
• !Agent user-agent paritybetarequirederror

  Browser UA received HTTP 200 with bot-challenge markers — cannot evaluate parity (the site may be blocking our scanner)

  Compared responses served to browser and AI-agent user-agents (informational while in beta)

  report issue
• ✗agents.mdrecommended0/3

  No agents.md: https://duolingo.com/agents.md → HTTP 200, https://duolingo.com/AGENTS.md → HTTP 200

  fix → Add /agents.md: what agents may do on your site, key URLs, auth, rate limits, and who to contact.

  Fetched /agents.md and checked for substantive agent guidance

  spec ↗report issue

Whether your pages carry machine-readable identity: structured data, llms.txt, clear copy an agent can quote.

• ✓Homepage states what you arerequired3/3

  Homepage clarity rated 5/5 — an agent can confidently say what this company does (model's one-sentence read: "Duolingo is a platform that helps users learn languages for free through a gamified and scientifically proven approach.")

  An LLM read your homepage as an agent would and rated how confidently it could say what you do

  report issue
• ✓OpenGraph / social metadatarecommended2/2

  Homepage has og:title, og:description, and og:image (twitter:card="summary" present)

  Parsed homepage og:title / og:description / og:image and twitter:card meta tags

  spec ↗report issue
• ✗llms.txtrecommended0/4

  /llms.txt returned HTML (content-type text/html), not markdown

  fix → Serve /llms.txt as plain markdown — an HTML page there is a routing catch-all, not an llms.txt.

  Fetched /llms.txt and validated it against the llmstxt.org shape (H1, summary, curated links)

  spec ↗report issue
• ✗llms-full.txtbonusrecommended0/2

  /llms-full.txt returned HTML (content-type text/html), not markdown

  fix → Serve /llms-full.txt as plain markdown, not an HTML page.

  Fetched /llms-full.txt and checked for substantial inline markdown content

  spec ↗report issue
• ✗JSON-LD structured datarequired0/4

  No application/ld+json blocks found on homepage and pricing page

  fix → Embed Organization + WebSite JSON-LD on your homepage (name, url, logo, sameAs) and Product/Offer JSON-LD on pricing.

  Extracted and validated application/ld+json blocks on the homepage and pricing page

  spec ↗report issue
• ✗Markdown content negotiationrecommended0/3

  GET / with `Accept: text/markdown` returned HTTP 200 text/html; no .md twins found (1 probed)

  fix → Serve text/markdown when clients send `Accept: text/markdown` (or expose .md twins of key pages) — agents get far more signal per token.

  Requested key pages with Accept: text/markdown and probed .md twin URLs

  report issue

Whether the artifacts an agent needs to build on you — docs, API specs, SDKs, MCP servers — exist and are findable.

• —Developer resource discoverabilityrecommendedna

  No public API detected

  Searched for your brand with developer-keyword suffixes and checked which official resources are cited

  report issue
• —OpenAPI spec discoverablerequiredna

  No public developer API detected — API checks don't apply

  Probed standard OpenAPI locations and docs links for a fetchable, parseable spec

  spec ↗report issue
• ✗Docs discoverablerequired0/4

  No docs found: probed 6 candidates (https://duolingo.com/docs, https://duolingo.com/documentation, https://duolingo.com/developers, https://duolingo.com/api, https://docs.duolingo.com/, https://developers.duolingo.com/)

  fix → Expose public docs at /docs or docs.duolingo.com and link them from your homepage nav.

  Followed homepage nav/footer links and probed /docs, /developers, docs.{domain}

  report issue
• ✗MCP server discoveryrequired0/5

  No MCP evidence found: probed /.well-known/mcp/server-card.json, /.well-known/mcp.json, /mcp.json and scanned llms.txt, agents.md, and docs for endpoints or install commands

  fix → Publish /.well-known/mcp/server-card.json describing your MCP endpoint so agents can autodiscover it. Evidence found: none.

  Probed /.well-known/mcp/server-card.json, mcp.json, and docs mentions for an MCP endpoint

  spec ↗report issue
• —npm SDKrecommendedna

  No public developer API detected — API checks don't apply

  Searched the npm registry for an official, domain-verified SDK package

  report issue
• —PyPI SDKrecommendedna

  No public developer API detected — API checks don't apply

  Searched PyPI for an official, domain-verified SDK package

  report issue

Whether your specs, docs, and tools are complete and descriptive enough for an agent to use them without guessing.

• —OpenAPI validity & qualityrecommendedna

  No public developer API detected — API checks don't apply

  Linted the spec: descriptions, operationIds, securitySchemes, servers

  report issue
• —Docs qualityrecommendedna

  No documentation found to evaluate

  An LLM rated your docs for clarity, completeness, runnable examples, and agent-friendliness

  report issue
• —Quickstart / getting startedrecommendedna

  No public developer API detected — API checks don't apply

  Looked for a quickstart/getting-started guide containing code blocks

  report issue
• —MCP tool qualityrecommendedna

  No MCP endpoint known — tool lint requires a tools/list

  Linted listed tools for descriptions, typed input schemas, and naming

  report issue

Response hygiene, TLS and redirect discipline, and security contact channels agents depend on at runtime.

• ✓TLS & redirect hygienerequired2/2

  http://duolingo.com/ upgrades to https in 1 hop(s), 1 redirect(s) total, final HTTP 200; no HSTS header

  Checked http→https redirect behavior, chain length, and TLS health

  report issue
• ✓Response speed & weightrequired1/1

  Homepage TTFB 36ms, payload 11KB, Content-Encoding: gzip

  Measured homepage TTFB, payload size, and compression

  report issue
• ✗security.txtrecommended0/1

  https://duolingo.com/.well-known/security.txt returned HTTP 404

  fix → Publish RFC 9116 /.well-known/security.txt with a Contact and a future Expires.

  Fetched /.well-known/security.txt and validated Contact + Expires

  spec ↗report issue

Whether agents can discover your auth model machine-readably (OAuth metadata) and follow documented steps to credentials.

• —OAuth authorization server metadatarecommendedna

  No API or MCP server detected — OAuth metadata doesn't apply

  Fetched /.well-known/oauth-authorization-server (and openid-configuration fallback)

  spec ↗report issue
• —OAuth protected resource metadatarecommendedna

  No API or MCP server detected — OAuth metadata doesn't apply

  Fetched /.well-known/oauth-protected-resource

  spec ↗report issue
• —Auth documentationrecommendedna

  No public developer API detected — API checks don't apply

  Looked for /auth.md or an authentication docs page with code examples

  report issue

Whether pricing is discoverable and machine-readable, and whether you support agent payment protocols.

• —Pricing discoverablerequiredna

  Product appears to be free or non-commercial — pricing checks don't apply

  Followed nav/footer links and probed /pricing for a page with legible price signals

  report issue
• —Machine-readable pricingrecommendedna

  Product appears to be free or non-commercial — pricing checks don't apply

  Looked for Offer JSON-LD, then had an LLM attempt structured extraction of your plans

  spec ↗report issue
• ✗x402 payment supportbonusrecommended0/2

  /.well-known/x402 returned HTTP 404. No x402 support detected (bonus check — absence costs nothing).

  fix → Support x402: serve payment requirements at /.well-known/x402, or answer unauthenticated API calls with HTTP 402 plus an x402 payment-requirements payload (x402Version, accepts[]).

  Probed /.well-known/x402 and API endpoints for HTTP 402 payment-required envelopes

  spec ↗report issue
• ✗AP2 readinessemerging0/1

  No AP2 hints found — scanned llms.txt, agents.md; /.well-known/ap2 returned HTTP 404.

  fix → Adopt AP2 to accept delegated agent payments — see https://ap2-protocol.org.

  Scanned fetched artifacts and well-known paths for AP2 hints

  spec ↗report issue
• ✗Agentic Commerce Protocolemerging0/1

  No Agentic Commerce Protocol hints found — scanned llms.txt, agents.md; /.well-known/acp returned HTTP 404.

  fix → Adopt the Agentic Commerce Protocol so agent checkouts can complete against your store — see https://developers.openai.com/commerce.

  Scanned docs and specs for agentic checkout endpoints

  spec ↗report issue
• ✗Other agent payment protocolsbonusemerging0/1

  No UCP/MPP hints found — scanned llms.txt, agents.md.

  fix → Track emerging agent payment protocols (UCP, MPP) and adopt the ones your buyers' agents use.

  Scanned fetched artifacts for UCP/MPP protocol hints

  report issue

Whether an end user's agent can operate on their behalf: working MCP tools, published skills, agent configs.

• —Agent skill publishedbonusemergingna

  Requires the analysis phase — not yet evaluated

  Checked /skill.md, /.well-known/skills/, and skills.sh for published agent skills

  report issue
• —MCP handshake & tools listrequiredna

  No MCP endpoint known — nothing to handshake with

  Performed a streamable-HTTP initialize + tools/list against the MCP endpoint

  spec ↗report issue
• —Agent configs in public repobonusemergingna

  Requires the analysis phase — not yet evaluated

  Checked your public GitHub org's main repos for AGENTS.md / .claude / .cursor configs

  report issue

Whether the site itself is legible to non-rendering and browser agents: semantic HTML, no JS walls, accessibility.

• ✗NLWeb endpointemerging0/1

  No NLWeb endpoint detected: /.well-known/nlweb.json returned HTTP 404 (text/html); GET /ask?query=hello returned HTTP 200 (text/html)

  fix → Consider exposing an NLWeb /ask endpoint (and /.well-known/nlweb.json) for conversational access to your content.

  Probed /.well-known/nlweb.json and the /ask endpoint

  spec ↗report issue
• ✗Semantic HTML structurerequired0/3

  Only 1/6 semantic signals present on the homepage (missing: <main> landmark, <nav> landmark, <header>/<footer>, exactly one <h1> (found 0), text-to-markup ratio ≥ 0.10)

  fix → Add landmark elements and a clean heading hierarchy — missing: <main> landmark, <nav> landmark, <header>/<footer>, exactly one <h1> (found 0), text-to-markup ratio ≥ 0.10.

  Scored landmark elements, heading hierarchy, and text-to-markup ratio on the homepage

  report issue
• ✗Content readable without JavaScriptrequired0/2

  Homepage raw HTML contains only 0 chars of visible text — an empty JS shell to non-rendering clients

  fix → Your homepage is an empty JS shell to non-rendering clients (0 chars of text). Server-render or prerender key pages — most agent fetchers don't execute JavaScript.

  Measured visible text in the raw, unrendered homepage HTML

  report issue
• ◐Accessibility basicsrequired1/2

  Homepage accessibility: 3/5 checks passed — failing: <html lang> attribute; ≥2 landmarks (found 0: none)

  fix → Failing: <html lang> attribute; ≥2 landmarks (found 0: none). The accessibility tree is what browser-operating agents see.

  Static checks: lang attribute, title, alt coverage, labeled inputs, landmarks

  report issue
• ✗WebMCPemerging0/1

  No WebMCP evidence on homepage: no application/webmcp script and no navigator.modelContext reference

  fix → Consider WebMCP to expose page actions as tools to browser agents.

  Looked for WebMCP script declarations on the homepage

  spec ↗report issue