HackMD

HackMD is a real-time collaborative Markdown editor and knowledge base for individuals and teams. Multiple people can co-edit a Markdown document live, organize notes into folders and team workspaces, and publish them as web pages, slide decks or books. HackMD exposes a v1 REST API at api.hackmd.io that lets developers programmatically create, read, update and delete personal and team notes, manage folders and folder ordering, upload image attachments, restore notes from trash, and read the current user profile and view history. The API authenticates with a personal access token sent as an HTTP bearer credential, is described by a published OpenAPI 3.0 specification and Swagger UI, ships an official Node.js/TypeScript client (@hackmd/api) and command-line interface, and advertises its full developer surface through an RFC 9727 api-catalog. HackMD is a Techstars-backed company.

HackMD publishes 8 API contracts indexed on the APIs.io network, including History API, Profile API, Team Folders API, and 5 more. Tagged areas include Company, Markdown, Collaboration, Documentation, and Note Taking.

HackMD’s developer surface includes documentation, API reference, getting-started guide, engineering blog, pricing, signup flow, changelog, and 24 more developer resources.

🌐 Visit website 📡 Source on GitHub

50.0/100 developing ▬ flat Agent 24/100 agent aware Front door AI 3/6 light saas Full breakdown ↓
scored 2026-10-17 · rubric v0.24.0

1 published contract

Company Markdown Collaboration Documentation Note Taking Knowledge Base Productivity Content

Kin Score

Kin Score How this is scored →
scored 2026-10-17 · rubric v0.24.0

Composite quality — 50.0/100 · developing

Contract Quality 8.7 / 19

Developer Ergonomics 10.3 / 15

Access Clarity 6.7 / 15

Operational Transparency 5.4 / 10

Contract Governance 0.4 / 9

Discoverability 5.5 / 8

Regulatory Posture 3.7 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 24/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 4 / 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 Horizontal (data, software, accessibility, platform) 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 applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% 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/hackmd: 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 →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Markdown

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

APIs 8

Individual APIs this provider publishes, each with its own machine-readable definition.

HackMD History API

Operations related to user's note history.

HackMD Profile API

Operations to retrieve user profile information.

HackMD Team Folders API

Operations related to folders within a team.

HackMD Team Notes API

Operations related to notes within a team.

HackMD Teams API

Operations related to user teams.

HackMD Trash API

Operations for listing and restoring trashed notes.

HackMD User Folders API

Operations related to a user's personal folders.

HackMD User Notes API

Operations related to a user's personal notes.

Scroll for all 8

Open Collections 9

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

HackMD Open History API

OPEN COLLECTION

HackMD Open History Profile API

OPEN COLLECTION

HackMD Open History Team Folders API

OPEN COLLECTION

HackMD Open History Team Notes API

OPEN COLLECTION

HackMD Open History Teams API

OPEN COLLECTION

HackMD Open History Trash API

OPEN COLLECTION

HackMD Open History User Folders API

OPEN COLLECTION

HackMD Open History User Notes API

OPEN COLLECTION

Scroll for all 9

Rate Limits 1

Documented rate limits and quota policies.

Hackmd Rate Limits

2 limits

RATE LIMITS

OpenAPI Overlays 1

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

Hackmd Openapi Overlay

3 actions · documentation · hackmd-openapi-original.json

UNRECORDED

Security Posture 2

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

Hackmd Authentication

http · 1 scheme

SECURITY

Hackmd Domain Security

TLSv1.2 · HSTS · DNSSEC · DMARC

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

SignUp

SignUp

Documentation 3

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

OpenAPI

OpenAPI

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

X-MCPServerCandidate

AgentSkill

LLMsTxt

WellKnown

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions

ErrorCatalog

Lifecycle

DataModel

Conformance

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

CLI

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 3

Status, limits, changes, and where to get help

StatusPage

StatusPage

ChangeLog

ChangeLog

RateLimits

RateLimits

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

Other 2

Properties that don't map to a standard resource type

Overlay

Overlay

APICatalog

APICatalog

Source (apis.yml)

aid: hackmd
name: HackMD
description: HackMD is a real-time collaborative Markdown editor and knowledge base for individuals and teams. Multiple people
  can co-edit a Markdown document live, organize notes into folders and team workspaces, and publish them as web pages, slide
  decks or books. HackMD exposes a v1 REST API at api.hackmd.io that lets developers programmatically create, read, update
  and delete personal and team notes, manage folders and folder ordering, upload image attachments, restore notes from trash,
  and read the current user profile and view history. The API authenticates with a personal access token sent as an HTTP bearer
  credential, is described by a published OpenAPI 3.0 specification and Swagger UI, ships an official Node.js/TypeScript client
  (@hackmd/api) and command-line interface, and advertises its full developer surface through an RFC 9727 api-catalog. HackMD
  is a Techstars-backed company.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - rate-limits
  - security
  generated: '2026-09-03'
  method: derived
image: https://hackmd.io/favicon.png
url: https://raw.githubusercontent.com/api-evangelist/hackmd/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- techstars
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Markdown
- Collaboration
- Documentation
- Note Taking
- Knowledge Base
- Productivity
- Content
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
apis:
- aid: hackmd:hackmd-history-api
  name: HackMD History API
  description: Operations related to user's note history.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - History
  properties:
  - type: OpenAPI
    url: openapi/hackmd-history-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-profile-api
  name: HackMD Profile API
  description: Operations to retrieve user profile information.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - Profiles
  tags_raw:
  - Profile
  properties:
  - type: OpenAPI
    url: openapi/hackmd-profile-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-team-folders-api
  name: HackMD Team Folders API
  description: Operations related to folders within a team.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - Team Folders
  properties:
  - type: OpenAPI
    url: openapi/hackmd-team-folders-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-team-notes-api
  name: HackMD Team Notes API
  description: Operations related to notes within a team.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - Team Notes
  properties:
  - type: OpenAPI
    url: openapi/hackmd-team-notes-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-teams-api
  name: HackMD Teams API
  description: Operations related to user teams.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - Team
  tags_raw:
  - Teams
  properties:
  - type: OpenAPI
    url: openapi/hackmd-teams-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-trash-api
  name: HackMD Trash API
  description: Operations for listing and restoring trashed notes.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - Trash
  properties:
  - type: OpenAPI
    url: openapi/hackmd-trash-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-user-folders-api
  name: HackMD User Folders API
  description: Operations related to a user's personal folders.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - User Folders
  properties:
  - type: OpenAPI
    url: openapi/hackmd-user-folders-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
- aid: hackmd:hackmd-user-notes-api
  name: HackMD User Notes API
  description: Operations related to a user's personal notes.
  humanURL: https://hackmd.io/@docs/developer-portal
  baseURL: https://api.hackmd.io/v1
  tags:
  - User Notes
  properties:
  - type: OpenAPI
    url: openapi/hackmd-user-notes-api-openapi.yml
  - type: APIReference
    url: https://api.hackmd.io/v1/docs/
  - type: Documentation
    url: https://hackmd.io/@docs/developer-portal
  - type: Authentication
    url: authentication/hackmd-authentication.yml
  - type: RateLimits
    url: rate-limits/hackmd-rate-limits.yml
common:
- type: Website
  url: https://hackmd.io/
- type: DeveloperPortal
  url: https://hackmd.io/@docs/developer-portal
- type: Documentation
  url: https://hackmd.io/@docs/developer-portal
- type: APIReference
  url: https://api.hackmd.io/v1/docs/
- type: GettingStarted
  url: https://hackmd.io/@docs/how-to-issue-an-api-token
- type: GitHubOrganization
  url: https://github.com/hackmdio
- type: Blog
  url: https://hackmd.io/blog
- type: Pricing
  url: https://hackmd.io/pricing
- type: SignUp
  url: https://hackmd.io/login
- type: TermsOfService
  url: https://hackmd.io/s/terms
- type: PrivacyPolicy
  url: https://hackmd.io/s/privacy
- type: StatusPage
  url: https://status.hackmd.io/
- type: ChangeLog
  url: changelog/hackmd-changelog.yml
- type: Authentication
  url: authentication/hackmd-authentication.yml
- type: OpenAPI
  url: openapi/_original/hackmd-openapi-original.json
- type: Overlay
  url: overlays/hackmd-openapi-overlay.yaml
- type: Packages
  url: packages/hackmd-packages.yml
- type: SDKs
  url: packages/hackmd-packages.yml
- type: CLI
  url: cli/hackmd-cli.yml
- type: X-MCPServerCandidate
  url: mcp/hackmd-mcp.yml
  note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list derived
    from the published API contracts, not an existing server. The scorer already read the manifest and reported mcp_server
    correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
- type: AgentSkill
  url: skills/_index.yml
- type: LLMsTxt
  url: llms/hackmd-llms.txt
- type: WellKnown
  url: well-known/hackmd-well-known.yml
- type: APICatalog
  url: well-known/hackmd-api-catalog.json
- type: Conventions
  url: conventions/hackmd-conventions.yml
- type: ErrorCatalog
  url: errors/hackmd-problem-types.yml
- type: RateLimits
  url: rate-limits/hackmd-rate-limits.yml
- type: Lifecycle
  url: lifecycle/hackmd-lifecycle.yml
- type: DataModel
  url: data-model/hackmd-data-model.yml
- type: Conformance
  url: conformance/hackmd-conformance.yml
- type: DomainSecurity
  url: security/hackmd-domain-security.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence

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