OnTopX402

OnTopX402 is a single public leaderboard of links in which rank is decided solely by the amount paid, settled in USDC over x402. There is no account, no API key and no card: an agent reads the board, decides what a position is worth, pays, and is listed in one request with no human involved. Three operations — read the leaderboard, read an entry, and bid. The bid endpoint returns an HTTP 402 payment challenge at x402 version 2, priced at a $1 minimum and payable in USDC on Base or Solana. Operated by One Scales Inc.

OnTopX402 publishes 2 APIs on the APIs.io network: Bidding API and Leaderboard API. Tagged areas include x402, USDC, Agent Payments, paid-placement, and Leaderboards.

OnTopX402’s developer surface includes authentication, pricing, and 13 more developer resources.

🌐 Visit website 📡 Source on GitHub

33.3/100 thin ▬ flat Agent 33/100 agent ready Front door AI 5/6 prominent Full breakdown ↓
scored 2026-09-19 · rubric v0.22.0

AccessOpen

2 APIs

x402 USDC Agent Paymentspaid-placementLeaderboards

Kin Score

Kin Score How this is scored →
scored 2026-09-19 · rubric v0.22.0

Composite quality — 33.3/100 · thin

Contract Quality 11.0 / 19

Developer Ergonomics 4.6 / 15

Access Clarity 4.7 / 15

Operational Transparency 0.0 / 10

Contract Governance 0.4 / 9

Discoverability 5.4 / 8

Regulatory Posture 4.0 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 33/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Payments regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/ontopx402: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 2

Individual APIs this provider publishes, each with its own machine-readable definition.

OnTopX402 Bidding API

The bidding API from OnTopX402 — 1 operation(s) for bidding.

OnTopX402 Leaderboard API

The leaderboard API from OnTopX402 — 2 operation(s) for leaderboard.

Pricing Plans 1

Published pricing tiers and plan structures.

Ontopx402 Plans Pricing

1 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Ontopx402 Rate Limits

0 limits

RATE LIMITS

Examples 1

Example request and response payloads for these APIs.

Ontopx402 Leaderboard Example

5 fields

EXAMPLE

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Ontopx402 Authentication

2 schemes

SECURITY

Ontopx402 Domain Security

TLSv1.3 · DMARC

SECURITY

Resources

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

AgentSkill

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Conventions

Idempotency

ErrorCatalog

Conformance

DataModel

Lifecycle

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

FinOps

FinOps

Plans

Plans

Pricing

Pricing

Company 1

The organization behind the API

Website

Website

Source (apis.yml)

aid: ontopx402
name: OnTopX402
description: 'OnTopX402 is a single public leaderboard of links in which rank is decided solely by the amount paid, settled
  in USDC over x402. There is no account, no API key and no card: an agent reads the board, decides what a position is worth,
  pays, and is listed in one request with no human involved. Three operations — read the leaderboard, read an entry, and bid.
  The bid endpoint returns an HTTP 402 payment challenge at x402 version 2, priced at a $1 minimum and payable in USDC on
  Base or Solana. Operated by One Scales Inc.'
type: Index
url: https://raw.githubusercontent.com/api-evangelist/ontopx402/refs/heads/main/apis.yml
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: true
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: open
  trial: false
  try_now: false
  public: true
  label: Open access
  confidence: low
  source: []
  generated: '2026-09-02'
  method: derived
created: '2026-08-24'
modified: '2026-09-03'
specificationVersion: '0.23'
tags:
- x402
- USDC
- Agent Payments
- paid-placement
- Leaderboards
tags_raw:
- x402
- usdc
- agent-payments
- paid-placement
- leaderboard
apis:
- aid: ontopx402:ontopx402-bidding-api
  name: OnTopX402 Bidding API
  description: The bidding API from OnTopX402 — 1 operation(s) for bidding.
  humanURL: https://ontopx402.com/
  baseURL: https://ontopx402.com
  tags:
  - Bidding
  tags_raw:
  - bidding
  properties:
  - type: OpenAPI
    url: openapi/ontopx402-bidding-api-openapi.yml
  - type: APIReference
    url: https://ontopx402.com/openapi.json
  - type: Documentation
    url: https://ontopx402.com/
  - type: FinOps
    url: finops/ontopx402-x402-challenge.json
  - type: Examples
    url: examples/ontopx402-leaderboard-example.json
  - type: Overlay
    url: overlays/ontopx402-bidding-api-overlay.yaml
- aid: ontopx402:ontopx402-leaderboard-api
  name: OnTopX402 Leaderboard API
  description: The leaderboard API from OnTopX402 — 2 operation(s) for leaderboard.
  humanURL: https://ontopx402.com/
  baseURL: https://ontopx402.com
  tags:
  - Leaderboards
  tags_raw:
  - leaderboard
  properties:
  - type: OpenAPI
    url: openapi/ontopx402-leaderboard-api-openapi.yml
  - type: APIReference
    url: https://ontopx402.com/openapi.json
  - type: Documentation
    url: https://ontopx402.com/
  - type: FinOps
    url: finops/ontopx402-x402-challenge.json
  - type: Examples
    url: examples/ontopx402-leaderboard-example.json
  - type: Overlay
    url: overlays/ontopx402-leaderboard-api-overlay.yaml
common:
- type: DomainSecurity
  url: security/ontopx402-domain-security.yml
- type: LLMsTxt
  url: llms/ontopx402-llms.txt
- type: Website
  url: https://ontopx402.com/
- type: FinOps
  url: finops/ontopx402-x402-challenge.json
- type: Authentication
  url: authentication/ontopx402-authentication.yml
- type: Conventions
  url: conventions/ontopx402-conventions.yml
- type: Idempotency
  url: conventions/ontopx402-conventions.yml
- type: ErrorCatalog
  url: errors/ontopx402-problem-types.yml
- type: Conformance
  url: conformance/ontopx402-conformance.yml
- type: DataModel
  url: data-model/ontopx402-data-model.yml
- type: Plans
  url: plans/ontopx402-plans-pricing.yml
- type: RateLimits
  url: rate-limits/ontopx402-rate-limits.yml
- type: Lifecycle
  url: lifecycle/ontopx402-lifecycle.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Pricing
  url: https://ontopx402.com/rules
maintainers:
- FN: One Scales Inc.
  email: info@ontopx402.com
  url: https://ontopx402.com/
x-provenance:
  added: '2026-08-24'
  method: searched
  source: https://ontopx402.com/llms.txt
  note: 'Submitted via apis.io/add on 2026-08-24 and auto-published by the gate at rating 48. The submitted APIs.json URL
    returns 404 against a control that also 404s, so it is a bad pointer in the submission rather than an absent surface.
    Everything here was found from the provider''s own llms.txt and OpenAPI. The x402 surface is real and was exercised. POST
    /api/bid with no payment header returns HTTP 402 carrying x402Version 2, a `payment-required` header, and two `accepts`
    entries: USDC on Base (eip155:8453) and on Solana, both at amount 1000000 (a $1 minimum), 300-second timeout. The challenge
    also carries a `bazaar` extension with full JSON Schema for the request body and an example response — an unusually complete
    machine-readable purchase contract. The saved file under finops/ is that response verbatim. GET /api/leaderboard returns
    the live board unauthenticated and is saved under examples/. WHAT THIS SERVICE IS, STATED PLAINLY, BECAUSE IT BEARS ON
    WHETHER WE SHOULD CARRY IT. This is paid placement. The provider says so itself: "Rank is decided by the amount paid,
    and nothing else… There is no editorial judgement, no quality score, no review… This is paid placement, and it says so
    plainly. Listing links are followed." Its own tags include backlink, seo, sponsored and paid-placement. It is honest,
    working, and technically excellent — and it is also a followed-backlink product, which is the category API Evangelist
    refuses when it arrives by email. Listed here on the standing rule that a valid company with a real API gets listed and
    the rating speaks; flagged for a policy decision rather than decided unilaterally.'
x-enrichment:
  date: '2026-09-03'
  status: enriched
  artifacts_added: 16
  pass: local-v2

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