aid: blockchalk
accessModel:
  pricing: unknown
  onboarding: open
  trial: false
  try_now: false
  public: true
  label: Open access
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/blockchalk.png
name: BlockChalk
description: >-
  BlockChalk was a location-based neighborhood messaging service founded in 2009 by Stephen
  Hood, the former product lead for Delicious, and Dave Baggeroer of the Stanford Institute of
  Design. Users with GPS-enabled smartphones left short public messages called "chalks" pinned
  to a specific geographic point, and read the chalks other people had left on their block, so
  neighbors could ask, answer, praise, gripe, report potholes and lost pets, announce garage
  sales and organize locally. The company raised $1M in seed financing in May 2010 from Joshua
  Schachter, Battery Ventures, Founder Collective, Harrison Metal, Mitch Kapor, Josh Stylman,
  Tom McInerney and David Liu. BlockChalk published a small read-only public API on its
  developer page, offering XML, JSON and RSS interfaces that returned nearby chalks for a
  supplied latitude and longitude, later joined by a versioned GeoRSS endpoint. The product
  and the company are retired: blockchalk.com holds an active domain registration but its
  delegated nameservers no longer resolve, and no BlockChalk host answers on the public
  internet. This profile preserves the historical API surface as documentation.
url: https://raw.githubusercontent.com/api-evangelist/blockchalk/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- battery-ventures
x-tier: stub
x-tier-reason: portfolio-lead
x-status: retired
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Company
- Location
- Geolocation
- Social
- Messaging
- Local
- Neighborhood
- Mobile
- Retired
apis:
- aid: blockchalk:blockchalk-chalks-api
  name: BlockChalk chalks API
  description: Location-pinned neighborhood messages.
  humanURL: http://web.archive.org/web/20090810213933/http://blockchalk.com/developers
  baseURL: http://blockchalk.com/api
  tags:
  - chalks
  properties:
  - type: OpenAPI
    url: openapi/blockchalk-chalks-api-openapi.yml
  - type: Examples
    url: examples/blockchalk-chalks-v0.6-georss-san-francisco.xml
  - type: Authentication
    url: authentication/blockchalk-authentication.yml
  - type: Conventions
    url: conventions/blockchalk-conventions.yml
  - type: DataModel
    url: data-model/blockchalk-data-model.yml
  - type: Lifecycle
    url: lifecycle/blockchalk-lifecycle.yml
  - type: Conformance
    url: conformance/blockchalk-conformance.yml
common:
- type: Documentation
  url: http://web.archive.org/web/20090810213933/http://blockchalk.com/developers
- type: APIReference
  url: http://web.archive.org/web/20090810213933/http://blockchalk.com/developers
- type: Packages
  url: packages/blockchalk-packages.yml
- type: WellKnown
  url: well-known/blockchalk-well-known.yml
- type: DomainSecurity
  url: security/blockchalk-domain-security.yml
- type: LLMsTxt
  url: llms/blockchalk-llms.txt
x-enrichment:
  date: '2026-07-20'
  status: enriched
  artifacts_added: 13
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io