Tsumobi

Tsumobi was a Y Combinator (Winter 2007) mobile messaging startup founded in Boston by Joshua Wilson and Adam Bouhenguel, and later backed by Andreessen Horowitz (a16z). It built a programming language that sat on top of J2ME so feature-phone applications could be downloaded and updated on the fly via URLs, aiming to fix the painful install and upgrade cycle of late-2000s mobile apps. The company is inactive (YC lists it as Inactive; reporting describes the startup as shut down after raising roughly $2M), the tsumobi.com domain no longer serves a website, and no public API, developer portal, SDKs, or specifications were found. This profile is retained as a historical a16z portfolio record in the API Evangelist network.

Tsumobi is profiled on the APIs.io network. Tagged areas include Company, Messaging, Mobile, J2ME, and Feature Phones.

🌐 Visit website 📡 Source on GitHub

7.4/100 minimal ▬ flat Agent 0/100 human only Full breakdown ↓
scored 2026-07-27 · rubric v0.5

0 APIs

CompanyMessagingMobileJ2MEFeature PhonesY CombinatorDefunct

Kin Score

Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5

Composite quality — 7.4/100 · minimal

Contract Quality 0.0 / 25

Developer Ergonomics 0.0 / 20

Commercial Clarity 0.0 / 20

Operational Transparency 0.7 / 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/tsumobi: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Company 1

The organization behind the API

Website

Website

Other 1

Properties that don't map to a standard resource type

Profile

Profile

Source (apis.yml)

aid: tsumobi
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/tsumobi.png
name: Tsumobi
description: Tsumobi was a Y Combinator (Winter 2007) mobile messaging startup founded in Boston by Joshua Wilson and Adam
  Bouhenguel, and later backed by Andreessen Horowitz (a16z). It built a programming language that sat on top of J2ME so feature-phone
  applications could be downloaded and updated on the fly via URLs, aiming to fix the painful install and upgrade cycle of
  late-2000s mobile apps. The company is inactive (YC lists it as Inactive; reporting describes the startup as shut down after
  raising roughly $2M), the tsumobi.com domain no longer serves a website, and no public API, developer portal, SDKs, or specifications
  were found. This profile is retained as a historical a16z portfolio record in the API Evangelist network.
url: https://raw.githubusercontent.com/api-evangelist/tsumobi/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- a16z
x-tier: stub
x-tier-reason: portfolio-lead
x-status: defunct
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Company
- Messaging
- Mobile
- J2ME
- Feature Phones
- Y Combinator
- Defunct
apis: []
common:
- type: DomainSecurity
  url: security/tsumobi-domain-security.yml
- name: Website (historical, no longer serving)
  type: Website
  url: http://tsumobi.com
- name: Y Combinator Profile
  type: Profile
  url: https://www.ycombinator.com/companies/tsumobi
- name: GitHub Organization
  type: GitHubOrganization
  url: https://github.com/tsumobi
- name: LLMs.txt
  type: LLMsTxt
  url: llms/tsumobi-llms.txt
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-07-21'
  status: minimal
  artifacts_added: 2
  pass: local-v1