Fifteenth

Fifteenth is a San Francisco-based fintech company operating an AI-powered personal tax platform for ambitious earners — founders, investors, executives, and technology professionals with complex financial situations such as equity compensation (ISOs, RSOs, RSUs, NSOs), liquidity events (IPOs and acquisitions), partnership income (K-1s), and active stock and crypto trading. The service pairs dedicated human CPAs with AI-driven automation: users link their banking, payroll, and investment accounts via one-click integrations (Workday, Rippling, Robinhood, Wealthfront, Carta, Charles Schwab, AngelList, Coinbase and more), and the platform automatically detects tax-relevant transactions, organizes documents, models scenarios, and delivers proactive quarterly planning plus unlimited year-round advice at flat-fee pricing starting around $1,000 per year. Fifteenth raised $8.25M in seed funding (February 2025) led by A* and General Catalyst. It is a consumer-facing product with no public developer API surface; this profile captures its identity and public web properties.

Fifteenth is profiled on the APIs.io network. Tagged areas include Company, Fintech, Taxes, Tax Preparation, and Tax Planning.

Fifteenth’s developer surface includes pricing, signup flow, engineering blog, support, and 6 more developer resources.

🌐 Visit website 📡 Source on GitHub

15.9/100 emerging ▬ flat Agent 0/100 human only saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

0 APIs

Company Fintech Taxes Tax Preparation Tax Planning Personal Finance Equity Compensation Accounting Artificial Intelligence

Kin Score

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

Composite quality — 15.9/100 · emerging

Contract Quality 0.0 / 25

Developer Ergonomics 1.4 / 20

Access Clarity 9.5 / 20

Operational Transparency 0.0 / 13

Contract Governance 0.0 / 12

Discoverability 5.0 / 10

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

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.

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/fifteenth: 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.

Fifteenth Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

SignUp

SignUp

Login

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

TrustCenter

TrustCenter

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 3

Pricing, plans, and the legal terms of use

Pricing

Pricing

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

aid: fifteenth
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://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/fifteenth.png
name: Fifteenth
description: 'Fifteenth is a San Francisco-based fintech company operating an AI-powered personal tax platform for ambitious
  earners — founders, investors, executives, and technology professionals with complex financial situations such as equity
  compensation (ISOs, RSOs, RSUs, NSOs), liquidity events (IPOs and acquisitions), partnership income (K-1s), and active stock
  and crypto trading. The service pairs dedicated human CPAs with AI-driven automation: users link their banking, payroll,
  and investment accounts via one-click integrations (Workday, Rippling, Robinhood, Wealthfront, Carta, Charles Schwab, AngelList,
  Coinbase and more), and the platform automatically detects tax-relevant transactions, organizes documents, models scenarios,
  and delivers proactive quarterly planning plus unlimited year-round advice at flat-fee pricing starting around $1,000 per
  year. Fifteenth raised $8.25M in seed funding (February 2025) led by A* and General Catalyst. It is a consumer-facing product
  with no public developer API surface; this profile captures its identity and public web properties.'
url: https://raw.githubusercontent.com/api-evangelist/fifteenth/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- general-catalyst
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Fintech
- Taxes
- Tax Preparation
- Tax Planning
- Personal Finance
- Equity Compensation
- Accounting
- Artificial Intelligence
apis: []
common:
- type: DomainSecurity
  url: security/fifteenth-domain-security.yml
- type: Website
  url: https://www.fifteenth.com/
- type: Pricing
  url: https://www.fifteenth.com/#Pricing
- type: SignUp
  url: https://login.fifteenth.com/sign-up
- type: Login
  url: https://app.fifteenth.com
- type: TermsOfService
  url: https://www.fifteenth.com/terms-of-use
- type: PrivacyPolicy
  url: https://www.fifteenth.com/privacy
- type: Blog
  url: https://www.fifteenth.com/resource-center
- type: Support
  url: mailto:hello@fifteenth.com
- type: TrustCenter
  url: https://app.drata.com/trust/9a0b5ee4-d65b-489a-bbdb-0fb41a42c1e3
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence

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