Radicale

Radicale provides a simple, open-source CalDAV and CardDAV server for calendars and contacts. It is lightweight, written in Python, and aims to be easy to install and configure, supporting multiple users and authentication methods. The project focuses on interoperability with various clients and offers a straightforward solution for personal and small‑team scheduling needs.

Radicale is listed with 1 API on the APIs.io network. Tagged areas include Company, CalDAV, CardDAV, OpenSource, and Python.

🌐 Visit website 📡 Profile data on GitHub

7.6/100 minimal Agent 6/100 agent aware Full breakdown ↓
scored 2026-10-31 · rubric v0.25.0 · Show this score on your site →

1 API

CompanyCalDAVCardDAVOpenSourcePython Calendar

Kin Score

Kin Score How this is scored →
scored 2026-10-31 · rubric v0.25.0

Composite quality — 7.6/100 · minimal

Contract Quality 0.0 / 21

Developer Ergonomics 1.2 / 17

Access Clarity 0.0 / 17

Operational Transparency 0.0 / 11

Contract Governance 1.9 / 10

Discoverability 4.6 / 9

Regulatory Posture 0.9 / 15

Agent readiness — 6/100 · agent aware

Machine-Readable Contract 0 / 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 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document
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

11 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points
Access Clarity scores 0.0 — up to +20.0 composite points
Developer Ergonomics scores 7.1 — up to +18.6 composite points

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/radicale/apis.yml: open an issue on github.com/api-evangelist/radicale 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.

Radicale API

Radicale is a small but powerful CalDAV (calendars, to‑do lists) and CardDAV (contacts) server offering calendar and contact synchronization via standard protocols.

Rate Limits 1

Documented rate limits and quota policies.

Radicale Rate Limits

0 limits

RATE LIMITS

Security Posture 2

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

Radicale Authentication

9 schemes

SECURITY

Radicale Domain Security

TLSv1.3

SECURITY

Resources

Build 2

SDKs, sample code, and the tooling you integrate with

SDKs

SDKs

Packages

Packages

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: radicale
name: Radicale
description: Radicale provides a simple, open-source CalDAV and CardDAV server for calendars and contacts. It is lightweight,
  written in Python, and aims to be easy to install and configure, supporting multiple users and authentication methods. The
  project focuses on interoperability with various clients and offers a straightforward solution for personal and small‑team
  scheduling needs.
url: https://raw.githubusercontent.com/api-evangelist/radicale/refs/heads/main/apis.yml
x-type: company
x-source: harvest:new-submission
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-27 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-27'
modified: '2026-10-27'
tags:
- Company
- CalDAV
- CardDAV
- OpenSource
- Python
- Calendar
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Hosts
  url: hosts/radicale-hosts.yml
- type: Vendors
  url: vendors/radicale-vendors.yml
- type: SDKs
  url: packages/radicale-packages.yml
- type: Packages
  url: packages/radicale-packages.yml
- type: DomainSecurity
  url: security/radicale-domain-security.yml
- type: Website
  url: https://radicale.org/
apis:
- name: Radicale API
  description: Radicale is a small but powerful CalDAV (calendars, to‑do lists) and CardDAV (contacts) server offering calendar
    and contact synchronization via standard protocols.
  humanURL: https://radicale.org/v3.html
  baseURL: null
  aid: radicale:radicale-api
x-submission-probe: 200, 2026-10-26
x-coverage:
  state: unreadable
  reason: js-rendered-docs
  detail: Documentation pages render via JavaScript and provide no machine‑readable OpenAPI or other contract.
  evidence:
  - url: https://radicale.org/v3.html
    status: 200
  checked: '2026-10-27'
x-enrichment:
  date: '2026-10-27'
  status: enriched
  artifacts_added: 8
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Radicale API — frequently asked questions

Does Radicale have an API?

Yes. APIs.io lists 1 API from Radicale, including Radicale API.

How do I authenticate with the Radicale API?

Radicale documents its authentication (9 schemes). The details are profiled on APIs.io as Radicale Authentication.

Is the Radicale API ready for AI agents?

Radicale has a Kin Score of 7.6 out of 100 (minimal) and an Agent Readiness score of 5.6 (agent-aware), scored by API Evangelist on 2026-10-31.

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