# Let's Encrypt

**Canonical:** https://apis.io/providers/lets-encrypt/  
**APIs profiled:** 7

Let's Encrypt is a free, automated, and open certificate authority run by the Internet Security Research Group affiliated with the Linux Foundation. It provides TLS certificates to secure the web, having issued billions of certificates to enable HTTPS for websites worldwide via the ACME protocol.

## Kin Score — 26.0 / 100 (emerging)

Scored 2026-08-25 under rubric 0.14.0. Trend: flat (+0.0 from 26.0).

| Facet | Score |
|---|---|
| Discoverability | 74.1 |
| Contract Quality | 45.4 |
| Governance | 0.0 |
| Contract Governance | 0.0 |
| Operational Transparency | 13.2 |
| Developer Ergonomics | 11.9 |
| Commercial Clarity | 15.8 |
| Access Clarity | 15.8 |

## Agent readiness — 17.3 (agent-aware)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | no |
| Error Semantics | no |
| OpenAPI Examples | no |
| Rate Limit Signal | documented |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |
| Delegated Identity | no |
| Protected Resource Metadata | no |
| Dynamic Client Registration | no |
| Agentic Commerce | no |

## Access

Freemium — onboarding: unknown, pricing: freemium, trial: no (confidence: medium).

## APIs (7)

- **Let's Encrypt Account API** — ACME account creation and management
- **Let's Encrypt Authorization API** — Domain control authorizations
- **Let's Encrypt Certificate API** — Issued certificate retrieval and revocation
- **Let's Encrypt Challenge API** — Validation challenges (HTTP-01, DNS-01, TLS-ALPN-01)
- **Let's Encrypt Directory API** — Discovery document listing ACME resources
- **Let's Encrypt Nonce API** — Anti-replay nonces for JWS-signed requests
- **Let's Encrypt Order API** — Certificate issuance orders

## Agentic access (1)

- **Lets Encrypt Agentic Access** — 12 operations · 10 acting · 1 human-in-the-loop

## Security (2)

- **Lets Encrypt Domain Security** — TLSv1.3 · HSTS · DMARC
- **Lets Encrypt Vulnerability Disclosure** — security.txt · contact published

## Plans (1)

- **Lets Encrypt Plans Pricing**

## Tags

Certificates, Linux Foundation, Security, TLS, ACME, PKI

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/lets-encrypt/). Scores are computed from the provider's own public artifacts under a published rubric.