Polymorph

Polymorph is a Y Combinator (Winter 2026) startup building adaptive consumer internet infrastructure that personalizes user experiences with AI agents. Founded in San Francisco by Andrew Sy, the platform runs thousands of continuous product and lifecycle-engagement experiments for its customers, each carrying the craft of that product's direction and brand, so consumer teams can scale experimentation in product surfaces without being bottlenecked by headcount or design capacity. Its stated vision is to make the consumer internet polymorphic — one that adapts to each user and optimizes for delightful experiences. As of this profile the company operates a marketing site only; it publishes no public API, developer documentation, SDKs, or developer portal.

Polymorph is profiled on the APIs.io network. Tagged areas include Company, Personalization, Experimentation, Consumer Internet, and Artificial Intelligence.

Polymorph’s developer surface includes legal docs, support, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub
13.2/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5
0 APIs
CompanyPersonalizationExperimentationConsumer InternetArtificial IntelligenceMachine LearningGrowthY Combinator

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 13.2/100 · minimal
Contract Quality 0.0 / 25
Developer Ergonomics 0.9 / 20
Commercial Clarity 4.2 / 20
Operational Transparency 1.4 / 13
Governance 0.0 / 12
Discoverability 6.8 / 10
Agent readiness — 0/100 · human only
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 15
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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/polymorph: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Security Posture 2

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

Polymorph Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Polymorph Vulnerability Disclosure

Hackerone · contact published

SECURITY

Resources

Access & Security 3

Authentication, authorization, and security posture

VulnerabilityDisclosure
VulnerabilityDisclosure
 Security
Security
 DomainSecurity
DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support
Support

Commercial 3

Pricing, plans, and the legal terms of use

TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy
 Legal
Legal

Company 2

The organization behind the API

Website
Website
 CrunchBase
CrunchBase

Other 1

Properties that don't map to a standard resource type

Y Combinator
Y Combinator

Source (apis.yml)

apis.yml Raw ↑ 
aid: polymorph
name: Polymorph
description: Polymorph is a Y Combinator (Winter 2026) startup building adaptive consumer internet infrastructure that personalizes
  user experiences with AI agents. Founded in San Francisco by Andrew Sy, the platform runs thousands of continuous product
  and lifecycle-engagement experiments for its customers, each carrying the craft of that product's direction and brand, so
  consumer teams can scale experimentation in product surfaces without being bottlenecked by headcount or design capacity.
  Its stated vision is to make the consumer internet polymorphic — one that adapts to each user and optimizes for delightful
  experiences. As of this profile the company operates a marketing site only; it publishes no public API, developer documentation,
  SDKs, or developer portal.
url: https://raw.githubusercontent.com/api-evangelist/polymorph/refs/heads/main/apis.yml
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://usepolymorph.com/polymorph-mark.png
x-type: company
x-source: vc-portfolio
x-backed-by:
- techstars
- y-combinator
x-tier: stub
x-tier-reason: portfolio-lead
x-website-note: Original getpolymorph.com domain from the portfolio source now resolves to an unrelated gambling site; the
  live company site is usepolymorph.com (confirmed via the Y Combinator company page, YC W26).
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Company
- Personalization
- Experimentation
- Consumer Internet
- Artificial Intelligence
- Machine Learning
- Growth
- Y Combinator
apis: []
x-enrichment:
  date: '2026-07-20'
  status: minimal
  artifacts_added: 2
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://usepolymorph.com/
- type: CrunchBase
  url: https://www.crunchbase.com/organization/polymorph-0146
- type: Y Combinator
  url: https://www.ycombinator.com/companies/polymorph
- type: TermsOfService
  url: https://usepolymorph.com/legal/terms
- type: PrivacyPolicy
  url: https://usepolymorph.com/legal/privacy
- type: Legal
  url: https://usepolymorph.com/legal
- type: Support
  url: mailto:founders@usepolymorph.com
- type: VulnerabilityDisclosure
  url: security/polymorph-vulnerability-disclosure.yml
- type: Security
  url: https://usepolymorph.com/legal/security
- type: DomainSecurity
  url: security/polymorph-domain-security.yml