Fatstack

Fatstack provides a marketplace of pay‑per‑call tools for AI agents, offering API and MCP tools that charge per request in USDC on the Base blockchain. Agents can discover tools, pay per call without accounts or API keys, and receive results directly. The platform emphasizes on‑chain payments, no custodial holdings, and transparent pricing, with a catalog of utilities like HTML‑to‑JSON, CSV‑to‑JSON, and cron expression explanations. It aims to simplify integration for AI agents while ensuring secure, decentralized transactions.

Fatstack is listed with 1 API on the APIs.io network. Tagged areas include Artificial Intelligence, Marketplace, Pay-per-call, Blockchain, and Tools.

Fatstack’s developer surface includes documentation, sandbox, API reference, getting-started guide, and 7 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

15.0/100 emerging Agent 4/100 human only Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

1 API 1 MCP Servers

Artificial Intelligence Marketplace Pay-per-call Blockchain Tools

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 15.0/100 · emerging

Contract Quality 0.0 / 21

Developer Ergonomics 6.1 / 17

Access Clarity 2.9 / 17

Operational Transparency 0.0 / 11

Contract Governance 0.0 / 10

Discoverability 4.8 / 9

Regulatory Posture 1.1 / 15

Agent readiness — 4/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 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

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) 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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document Ask about this →
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author Ask about this →
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey) Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →

12 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points Ask about this →
Access Clarity scores 17.0 — up to +16.6 composite points Ask about this →
Operational Transparency scores 0.0 — up to +13.0 composite points Ask about this →

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

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 the provider profile at artifacts.apis.io/fatstack-net/apis.yml: open an issue on github.com/api-evangelist/fatstack-net to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Model Context Protocol (MCP)

measured — observed by APIs.io (documented)

APIs 1

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

Payments API

API for managing payments on Fatstack platform.

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Fatstack MCP Server

Remote MCP server at www.fatstack.net.

MCP SERVER

Security Posture 1

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

Fatstack Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

Sandbox

Sandbox

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

MCPServer

MCPServer

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: fatstack-net
name: Fatstack
description: Fatstack provides a marketplace of pay‑per‑call tools for AI agents, offering API and MCP tools that charge per
  request in USDC on the Base blockchain. Agents can discover tools, pay per call without accounts or API keys, and receive
  results directly. The platform emphasizes on‑chain payments, no custodial holdings, and transparent pricing, with a catalog
  of utilities like HTML‑to‑JSON, CSV‑to‑JSON, and cron expression explanations. It aims to simplify integration for AI agents
  while ensuring secure, decentralized transactions.
url: https://artifacts.apis.io/fatstack-net/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-07 (modular-v1; was harvest)
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - security
  generated: '2026-11-13'
  method: derived
specificationVersion: '0.20'
created: '2026-11-07'
modified: '2026-11-07'
tags:
- Artificial Intelligence
- Marketplace
- Pay-per-call
- Blockchain
- Tools
tags_raw:
- AI
- Marketplace
- Pay-per-call
- Blockchain
- Tools
image: https://www.fatstack.net/logo.png
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Documentation
  url: https://www.fatstack.net/docs/payments
- type: MCPServer
  url: mcp/fatstack-net-mcp.yml
- type: Hosts
  url: hosts/fatstack-net-hosts.yml
- type: Vendors
  url: vendors/fatstack-net-vendors.yml
- type: Sandbox
  url: https://www.fatstack.net/console
- type: DomainSecurity
  url: security/fatstack-net-domain-security.yml
- type: Website
  url: https://fatstack.net/
- type: APIReference
  url: https://www.fatstack.net/docs/mcp
- type: GettingStarted
  url: https://www.fatstack.net/docs/mcp
- type: TermsOfService
  url: https://www.fatstack.net/legal/terms
- type: PrivacyPolicy
  url: https://www.fatstack.net/legal/privacy
apis:
- name: Payments API
  description: API for managing payments on Fatstack platform.
  humanURL: https://www.fatstack.net/docs/payments
  baseURL: null
  aid: fatstack-net:payments-api
x-enrichment:
  date: '2026-11-07'
  status: enriched
  artifacts_added: 11
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Fatstack API — frequently asked questions

Does Fatstack have an API?

Yes. APIs.io lists 1 API from Fatstack, including Payments API.

Does Fatstack have an MCP server?

Yes. APIs.io lists 1 MCP server for Fatstack: Remote MCP server at www.fatstack.net.

Is the Fatstack API ready for AI agents?

Fatstack has a Kin Score of 15.0 out of 100 (emerging) and an Agent Readiness score of 3.5 (human-only), scored by API Evangelist on 2026-11-13.

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

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get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
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