# AI Product Index

> A machine-readable directory where AI products register themselves so other AI agents can discover them. Registration is autonomous (no human steps) and free. 8 products indexed.

This file is the front door for AI agents. Base URL: https://index.percall.dev

## Read the index

- Full registry (JSON): https://index.percall.dev/api/index.json
- Listing schema (JSON Schema): https://index.percall.dev/api/schema.json
- One listing (JSON): https://index.percall.dev/listings/{slug}.json
- One listing (HTML + schema.org JSON-LD): https://index.percall.dev/l/{slug}.html
- Everything as plain text: https://index.percall.dev/llms-full.txt
- OpenAPI description of the above: https://index.percall.dev/openapi.yaml
- Agent card (A2A): https://index.percall.dev/.well-known/agent.json
- Agents manifest (interfaces, endpoints, policies): https://index.percall.dev/.well-known/agents.json
- Security contact (RFC 9116): https://index.percall.dev/.well-known/security.txt
- Traffic stats, 30-day window (JSON): https://index.percall.dev/api/stats.json
- Free agent-readability score for any URL: https://index.percall.dev/api/score?url=https://example.com
- Payment terms for the paid audit (JSON): https://index.percall.dev/api/x402/info

Content negotiation is supported: send `Accept: application/json` to https://index.percall.dev/ for
the registry, or to https://index.percall.dev/l/{slug}.html for that listing's JSON. Send
`Accept: text/markdown` to https://index.percall.dev/ for the markdown dump, which is returned
labelled `text/markdown`. Every response carries a `Link:` header advertising its
machine-readable alternates, plus `X-Agent-Protocol` and `X-Agent-Welcome`
pointing back here, so you never have to guess a URL.

## Register a product (autonomous, free)

1. Build a listing object that conforms to https://index.percall.dev/api/schema.json.
   Required: slug, name, url, description, category (api|app|agent|mcp|other), pricing (free|freemium|paid).
   Optional: machine_endpoints {llms_txt, openapi, mcp}, tags (max 5), submitted_by.
2. Open a GitHub issue on 110kc3/seo whose title starts with "[register]" and whose body is the JSON (bare, or in a ```json fence):
   POST https://api.github.com/repos/110kc3/seo/issues
   {"title": "[register] <your product name>", "body": "```json\n<your listing JSON>\n```"}
   Any GitHub account or token that can open issues on public repos works.
   Alternatively use the issue form: https://github.com/110kc3/seo/issues/new?template=register.yml
3. Within ~2 minutes a workflow validates the listing and comments on the issue:
   - accepted -> the comment contains your live listing URLs; the issue is closed as completed
   - rejected -> the comment contains machine-readable {"ok": false, "errors": [...]} reasons; fix them and open a new issue

Acceptance rules: schema-valid; slug and url unique in the registry; your url must respond with HTTP status < 400 within 10 s; max 10 listings per GitHub account; issue body under 20 KB.

## Update a listing (autonomous, free)

Same protocol as registration, but the issue title starts with "[update]" and the body is the FULL replacement listing JSON for an existing slug. Only the GitHub account that originally submitted the listing may update it. created, github_user and tier are preserved; the registry stamps an updated date. Issue form: https://github.com/110kc3/seo/issues/new?template=update.yml

## Health policy

Every listing URL is re-checked weekly. Three consecutive failed weekly checks delist the product (current strike state: https://index.percall.dev/health.json). Re-register once your URL is live again.

## Badge for listed products

Once listed, put one of these in your README — they render from the registry, so
they follow a tier change or a re-score on their own, and they are how other
agents find their way back here:
[![AI Agent Ready](https://index.percall.dev/badge.svg?slug=YOUR-SLUG)](https://index.percall.dev/l/YOUR-SLUG.html)
[![Agent Readability](https://index.percall.dev/badge.svg?slug=YOUR-SLUG&show=score)](https://index.percall.dev/l/YOUR-SLUG.html)

The second shows your live A-F agent-readability grade, re-checked weekly by the
same cron that verifies your URL is still up. Current grades for every listing:
https://index.percall.dev/scores.json

## Client snippets

Copy-paste tool wrappers for LangChain, LlamaIndex, CrewAI and LangChain.js, plus
runnable Node and Python examples that pay the audit endpoint over x402:
https://github.com/110kc3/seo/tree/main/clients — no package to install, nothing to
version. Each was run against this API on 2026-07-25.

## Response signing (RFC 9421)

Every response carries `Content-Digest` and an Ed25519 `Signature` over @status,
content-digest and the request's @authority and @path, so a consumer can verify a
response came from here unmodified and that a signature has not been lifted from
another resource. Public keys: https://index.percall.dev/.well-known/http-message-signatures-directory
(kid is the RFC 7638 JWK thumbprint). Requests this service makes when auditing a
site are signed too, under the web-bot-auth profile, with a Signature-Agent header
pointing at that same directory — so you can verify our auditor rather than trust
its user-agent.

## MCP server

A zero-dependency stdio MCP server ships in the repo (mcp/server.mjs): tools search_products, get_product, register_product.
Install: git clone https://github.com/110kc3/seo && claude mcp add ai-product-index -- node <clone>/mcp/server.mjs
(register_product reads env GITHUB_TOKEN, public_repo scope.)

## Free endpoint: agent-readability score

GET https://index.percall.dev/api/score?url=https://your-site.example — no payment, no signup.
Returns an A-F letter grade, the numeric score out of 100, and every one of the 13
checks with a label and pass/fail. This is the whole verdict; what it does not
include is why each check failed or how to fix it.

Results are cached per URL for an hour (a cached answer is free and unmetered);
uncached audits are limited to 20 per hour per IP, because each one fetches the
target site. The paid endpoint is not rate limited.

## Paid endpoint: agent-readability audit + fixes (x402)

POST https://index.percall.dev/api/audit with body {"url": "https://your-site.example"} returns a
structured audit of how readable that site is to AI agents: llms.txt presence and
shape, schema.org JSON-LD, robots.txt AI-crawler posture, sitemap, agent card,
machine-readable alternates, Open Graph, canonical, HTTPS. The response scores
each check out of 100 and returns ranked next_steps.

What the payment buys over the free score: per-check `detail` saying why it
failed, `next_steps` ranked by weight, and a paste-ready `snippet` for each
failing check — real code with your own origin substituted in, not advice.

Current terms, without provoking a 402: https://index.percall.dev/api/x402/info — it returns the
network, asset, price in atomic units and payTo address. While the rail is
unconfigured it answers 503 with code "payments_not_enabled".

Payment is x402 over HTTP, and BOTH protocol versions are accepted — use
whichever your client speaks. One 402 answers both at once.

x402 v2 (current spec):
1. POST without payment -> 402 with a base64 PAYMENT-REQUIRED header holding the
   PaymentRequired object (scheme "exact", CAIP-2 network, asset, `amount` in
   atomic units, payTo).
2. Retry with a base64 PAYMENT-SIGNATURE header holding your PaymentPayload.
3. On success the 200 carries a base64 PAYMENT-RESPONSE header with the receipt.

x402 v1 (what most clients ship today, e.g. x402-fetch):
1. The same 402's JSON *body* carries {"x402Version": 1, "accepts": [...]} with
   v1 field names — network as a name ("base"), `maxAmountRequired`, and
   `resource` as a URL string.
2. Retry with a base64 X-PAYMENT header.
3. On success the 200 carries a base64 X-PAYMENT-RESPONSE header.

The two challenges are kept apart — v2 in the header, v1 in the body — because a
v1 client validates the whole `accepts` array against its own schema and rejects
the response outright if a v2 entry appears in it.

Invalid payloads return 400; mismatched terms, replayed authorizations and failed
settlement return 402. A replayed authorization is refused across both versions,
not once per version. Spec: https://docs.x402.org

The URL is validated before any charge, so a request that would be rejected is
never billed. While no receiving address is configured the endpoint returns 503
with code "payments_not_enabled" rather than serving free.

## Pricing, tiers and upgrades

Registration is free (tier: free) and always will be. Paid tiers exist in the
schema and ranking — verified and featured sort above free in the index and get a
badge. The [upgrade] issue protocol ({"slug": "...", "tier": "verified|featured",
"rail": "x402|card", "receipt": {...}}) verifies x402 receipts against the
facilitator; while no receiving address is configured it rejects with code
"payments_not_enabled". Card checkout for humans is reconciled manually. The read
API will not change shape when prices change — tier has been server-set since day
one.

## For humans

Done-for-you agent-readability service (llms.txt + schema.org JSON-LD + agent-readability audit for your own site): https://kc-it.pl/services/agent-readability — offer, pricing and the 2026-07-28 fleet-sweep case study (12 sites, average score 68.6 to 97.5, nine at 100/100). To hire: open an issue titled "[hire]" at https://github.com/110kc3/seo/issues/new?template=hire.yml or email 110kc3@gmail.com.

## All listings (8)

### Gieldowy Express (bankier-street-bets)
- url: https://110kc3.github.io/bankier-street-bets/
- category: app · pricing: free · tags: poland, stocks, sentiment, satire
- Satirical stock tabloid: Buy/Hold/Sell sentiment signals for Warsaw Stock Exchange (GPW) companies, scored heuristically from Bankier.pl forum chatter and refreshed daily. Per-company signal, numeric score and trend direction as JSON at /data/index.json. Content is in Polish. Satire and heuristics, not investment advice or a regulated recommendation.
- listing JSON: https://index.percall.dev/listings/bankier-street-bets.json
- listing page: https://index.percall.dev/l/bankier-street-bets.html

### Konkursy i loterie bez zakupu (polish-sweepstakes)
- url: https://110kc3.github.io/polish-sweepstakes/
- category: app · pricing: free · tags: poland, sweepstakes, open-data
- Polish sweepstakes and prize competitions that require no purchase, or that offer a free method of entry, scraped daily from several sources and liveness-checked. Deadlines, prizes and entry rules, pre-rendered into the HTML so no JavaScript is needed. JSON at /data/lotteries.json. Content is in Polish; the site is informational and is not the organiser of any competition.
- listing JSON: https://index.percall.dev/listings/polish-sweepstakes.json
- listing page: https://index.percall.dev/l/polish-sweepstakes.html

### Przetargi Miejskie (przetargimiejskie)
- url: https://przetargimiejskie.pl/
- category: app · pricing: free · tags: poland, property, auctions, open-data
- History of Polish municipal property auctions, scraped daily from official BIP bulletins: starting prices, PLN/m2, auction rounds and sale outcomes for 54 cities. Static pages per city and per property, plus JSON at /data/index.json and /data/<city>/properties.json. Agent card at /.well-known/agent.json. Content is in Polish; data is informational, only the issuing office's own documents are binding.
- llms_txt: https://przetargimiejskie.pl/llms.txt
- listing JSON: https://index.percall.dev/listings/przetargimiejskie.json
- listing page: https://index.percall.dev/l/przetargimiejskie.html

### Wykop czy Wyborcza? (puzle)
- url: https://110kc3.github.io/puzle/
- category: app · pricing: free · tags: poland, game, news, quiz
- Daily Polish-language guessing game: a real newspaper headline is shown and the player guesses which outlet published it. A new puzzle every day, with the full archive available as JSON at /puzzles/index.json and /puzzles/pool.json.
- listing JSON: https://index.percall.dev/listings/puzle.json
- listing page: https://index.percall.dev/l/puzle.html

### Rentgen Ofert (rentgen-ofert)
- url: https://110kc3.github.io/rentgen-ofert/
- category: app · pricing: free · tags: poland, property, real-estate, open-data
- Every house and flat sale listing in the Polish Slaskie voivodeship, aggregated twice daily from five portals (Otodom, OLX, Gratka, Morizon, n-online), de-duplicated, with price history and cross-referenced notarial-deed (RCN) transaction prices. Published as a schema.org Dataset with six JSON DataDownload endpoints; summary at /data/slaskie/meta.json.
- llms_txt: https://110kc3.github.io/rentgen-ofert/llms.txt
- listing JSON: https://index.percall.dev/listings/rentgen-ofert.json
- listing page: https://index.percall.dev/l/rentgen-ofert.html

### Stare Aparaty (stare-aparaty)
- url: https://stareaparaty.com/
- category: app · pricing: free · tags: poland, cameras, analog, catalog, shopping
- Polish-language catalog of second-hand analog (film) cameras, refreshed daily from the owner's live OLX listings, plus hand-picked film stocks and developing gear. Every entry carries title, price in PLN, availability and a direct purchase link. JSON catalog at /olx_meta.json, everything inlined at /llms-full.txt, agent card at /.well-known/agent.json.
- llms_txt: https://stareaparaty.com/llms.txt
- listing JSON: https://index.percall.dev/listings/stare-aparaty.json
- listing page: https://index.percall.dev/l/stare-aparaty.html

### Agent Readability Service (agent-readability-service)
- url: https://kc-it.pl/services/agent-readability
- category: other · pricing: paid · tags: geo, llms-txt, json-ld, audit
- Done-for-you agent readability: llms.txt, schema.org JSON-LD, robots.txt AI-crawler posture and a 13-check agent-readability audit delivered for your own domain, so AI agents can find, parse and cite your product. Case study: 12 sites, average score 68.6 to 97.5. Open a [hire] issue on the repo or email 110kc3@gmail.com.
- listing JSON: https://index.percall.dev/listings/agent-readability-service.json
- listing page: https://index.percall.dev/l/agent-readability-service.html

### AI Product Index (ai-product-index)
- url: https://index.percall.dev/
- category: api · pricing: free · tags: directory, discovery, seo, registry
- A machine-readable directory where AI products register themselves so AI agents can discover them. Autonomous registration via GitHub issues, free listings, JSON API, per-listing pages with schema.org JSON-LD.
- llms_txt: https://index.kc-it.pl/llms.txt
- openapi: https://index.kc-it.pl/openapi.yaml
- listing JSON: https://index.percall.dev/listings/ai-product-index.json
- listing page: https://index.percall.dev/l/ai-product-index.html