mCaptcha

mCaptcha provides a proof‑of‑work based captcha system that is privacy‑focused, fully automated, and open source. It protects websites from automated abuse without tracking users, offering a silent, user‑friendly experience. The service includes drop‑in compatibility with reCAPTCHA and hCaptcha, extensive documentation, and client libraries under permissive licenses, while the core remains AGPL‑licensed.

mCaptcha is listed with 1 API on the APIs.io network: Guard API. Tagged areas include Company, Captcha, Privacy, OpenSource, and PoW.

mCaptcha’s developer surface includes CLI, documentation, API reference, getting-started guide, support, engineering blog, and 9 more developer resources.

🌐 Visit website📡 Profile data on GitHub
29.9/100 thin Agent 19/100 agent aware Full breakdown ↓
scored 2026-10-31 · rubric v0.25.0 · Show this score on your site →
1 API
CompanyCaptchaPrivacyOpenSourcePoWSecurity

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-10-31 · rubric v0.25.0
Composite quality — 29.9/100 · thin
Contract Quality 6.2 / 21
Developer Ergonomics 8.9 / 17
Access Clarity 1.8 / 17
Operational Transparency 1.7 / 11
Contract Governance 0.5 / 10
Discoverability 5.6 / 9
Regulatory Posture 3.1 / 15
Agent readiness — 19/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 10
Documented Reversibility 0 / 6
MCP Server 12 / 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 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
Pagination 5 / 5
Distinct Operations 3 / 3
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 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.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Show this score on your site. Kin Score badge preview for mCaptcha It updates itself when the score changes. Paste this where you link to your API docs: 
<a href="https://apis.io/providers/mcaptcha/"><img src="https://apis.io/badge/mcaptcha/card.svg" alt="mCaptcha on APIs.io — Kin Score by API Evangelist"></a>
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Agent readiness — checks not met, largest first (exact, from this profile):
  • Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
  • Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
  • Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
  • A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
  • Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
  • Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
10 more unmet checks in the Agent Readiness table above.
Kin Score — facets with the most composite points still available (weight × headroom):
Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.
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 the provider profile at artifacts.apis.io/mcaptcha/apis.yml: open an issue on github.com/api-evangelist/mcaptcha to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

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

mCaptcha Guard API

API for mCaptcha user registration, authentication, and account management.

Security Posture 2

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

Mcaptcha Domain Security

TLSv1.3 · DNSSEC

SECURITY

Mcaptcha Vulnerability Disclosure

no policy recorded

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Conformance
Conformance

Build 2

SDKs, sample code, and the tooling you integrate with

CLI
CLI
 GitHubOrganization
GitHubOrganization

Access & Security 3

Authentication, authorization, and security posture

Security
Security
 VulnerabilityDisclosure
VulnerabilityDisclosure
 DomainSecurity
DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support
Support

Commercial 1

Pricing, plans, and the legal terms of use

PrivacyPolicy
PrivacyPolicy

Company 2

The organization behind the API

Website
Website
 Blog
Blog

Other 1

Properties that don't map to a standard resource type

Hosts
Hosts

Source (apis.yml)

apis.yml Raw ↑ 
aid: mcaptcha
name: mCaptcha
description: mCaptcha provides a proof‑of‑work based captcha system that is privacy‑focused, fully automated, and open source.
  It protects websites from automated abuse without tracking users, offering a silent, user‑friendly experience. The service
  includes drop‑in compatibility with reCAPTCHA and hCaptcha, extensive documentation, and client libraries under permissive
  licenses, while the core remains AGPL‑licensed.
image: https://mcaptcha.org/static/images/landing.jpg
url: https://artifacts.apis.io/mcaptcha/apis.yml
x-type: company
x-source: harvest:new-submission
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-28 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-28'
modified: '2026-10-28'
tags:
- Company
- Captcha
- Privacy
- OpenSource
- PoW
- Security
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: CLI
  url: cli/mcaptcha-cli.yml
- type: Conformance
  url: conformance/mcaptcha-conformance.yml
- type: Hosts
  url: hosts/mcaptcha-hosts.yml
- type: Security
  url: https://mcaptcha.org/security
- type: VulnerabilityDisclosure
  url: security/mcaptcha-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/mcaptcha-domain-security.yml
- type: Website
  url: https://mcaptcha.org/
- type: DeveloperPortal
  url: https://mcaptcha.org/docs/
- type: Documentation
  url: https://mcaptcha.org/docs/
- type: APIReference
  url: https://mcaptcha.org/docs/api/
- type: GettingStarted
  url: https://mcaptcha.org/docs/webmasters/installing-captcha/
- type: Support
  url: https://mcaptcha.org/contact/
- type: Blog
  url: https://mcaptcha.org/blog/
- type: GitHubOrganization
  url: https://github.com/mCaptcha
- type: PrivacyPolicy
  url: https://mcaptcha.org/privacy-policy/
apis:
- name: mCaptcha Guard API
  description: API for mCaptcha user registration, authentication, and account management.
  humanURL: https://mcaptcha.org/docs/api/
  baseURL: https://api.mcaptcha.org
  properties:
  - type: OpenAPI
    url: openapi/mcaptcha-openapi.yml
  aid: mcaptcha:mcaptcha-guard-api
x-submission-probe: 200, 2026-10-26
x-enrichment:
  date: '2026-10-28'
  status: enriched
  artifacts_added: 12
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

mCaptcha API — frequently asked questions

Does mCaptcha have an API?

Yes. APIs.io lists 1 API from mCaptcha, including mCaptcha Guard API.

Is there an OpenAPI specification for the mCaptcha API?

Yes. APIs.io indexes 1 OpenAPI specification for mCaptcha, each linked for download from this page.

Is the mCaptcha API ready for AI agents?

mCaptcha has a Kin Score of 29.9 out of 100 (thin) and an Agent Readiness score of 18.9 (agent-aware), scored by API Evangelist on 2026-10-31.

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