Napkin Math

Napkin Math is a personalized AI food journal from Paper Star (a Y Combinator company, founded 2026 in San Francisco by Manuel Castro, Claire Nord, and Jynnie Tang). Marketed as "an AI nutrition coach in your pocket," it is a simple, beautiful food diary that helps people log meals and understand their eating habits over time. The product is a consumer mobile application rather than a developer platform: as of this profile Napkin Math publishes no public API, developer documentation, SDKs, OpenAPI, MCP server, or /.well-known discovery surface. This entry is maintained in the API Evangelist network as a company profile and enrichment lead; it will be upgraded to carry API artifacts if and when Napkin Math or Paper Star exposes a public API surface.

Napkin Math is profiled on the APIs.io network. Tagged areas include Company, Nutrition, Food Journal, Health, and Diet.

🌐 Visit website 📡 Source on GitHub

9.0/100 minimal ▬ flat Agent 0/100 human only saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

0 APIs

Company NutritionFood JournalHealth Diet Artificial Intelligence Consumer Application Mobile Application iOS

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 9.0/100 · minimal

Contract Quality 0.0 / 21

Developer Ergonomics 0.0 / 17

Access Clarity 3.6 / 17

Operational Transparency 0.0 / 11

Contract Governance 0.0 / 10

Discoverability 4.3 / 9

Regulatory Posture 2.6 / 15

Agent readiness — 0/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 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

Regulatory Posture applies to this provider. Its tags matched the Health 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/.

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/napkin-math: 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 →

Security Posture 1

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

Napkin Math Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

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

Source (apis.yml)

aid: napkin-math
name: Napkin Math
description: 'Napkin Math is a personalized AI food journal from Paper Star (a Y Combinator company, founded 2026 in San Francisco
  by Manuel Castro, Claire Nord, and Jynnie Tang). Marketed as "an AI nutrition coach in your pocket," it is a simple, beautiful
  food diary that helps people log meals and understand their eating habits over time. The product is a consumer mobile application
  rather than a developer platform: as of this profile Napkin Math publishes no public API, developer documentation, SDKs,
  OpenAPI, MCP server, or /.well-known discovery surface. This entry is maintained in the API Evangelist network as a company
  profile and enrichment lead; it will be upgraded to carry API artifacts if and when Napkin Math or Paper Star exposes a
  public API surface.'
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source: []
  generated: '2026-07-22'
  method: derived
image: https://napkinmath.club/opengraph-image.png
url: https://raw.githubusercontent.com/api-evangelist/napkin-math/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- y-combinator
x-parent-company: Paper Star
x-tier: stub
x-tier-reason: consumer-app-no-api
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Company
- Nutrition
- Food Journal
- Health
- Diet
- Artificial Intelligence
- Consumer Application
- Mobile Application
- iOS
common:
- url: https://napkinmath.club
  type: Website
- url: https://www.paperstar.cc/napkin-math/terms
  type: TermsOfService
- url: https://www.paperstar.cc/napkin-math/terms
  type: PrivacyPolicy
- url: security/napkin-math-domain-security.yml
  type: DomainSecurity
apis: []
x-enrichment:
  date: '2026-07-20'
  status: nochange
  artifacts_added: 0
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io

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