# Signal

**Canonical:** https://apis.io/providers/signal/  
**Website:** https://signal.org/  
**APIs profiled:** 14

Signal is a privacy-focused messaging platform that provides end-to-end encrypted communication through open-source applications on mobile and desktop. Their developer ecosystem centers around the open-source Signal Protocol, client SDKs, and server infrastructure, enabling developers to study, audit, and integrate secure messaging capabilities. The Signal Protocol is the most widely deployed end-to-end encryption protocol in the world, used by Signal, WhatsApp, Google Messages, and other platforms.

## Kin Score — 41.5 / 100 (developing)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 41.5).

| Facet | Score |
|---|---|
| Discoverability | 64.8 |
| Contract Quality | 77.9 |
| Governance | 13.6 |
| Contract Governance | 13.6 |
| Operational Transparency | 10.5 |
| Developer Ergonomics | 28.6 |
| Commercial Clarity | 34.2 |
| Access Clarity | 34.2 |

## Agent readiness — 30.3 (agent-aware)

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

## Access

Paid · Self-serve signup — onboarding: self-serve, pricing: paid, trial: no (confidence: high).

## APIs (14)

- **Signal Protocol Specifications** — The Signal Protocol Specifications define the core cryptographic protocols that underpin Signal's end-to-end encrypted messaging. These include the X3DH (Extended Triple Diffie-...
- **Signal libsignal SDK** — The libsignal SDK provides platform-agnostic APIs used by the official Signal clients and server. It implements the Signal Protocol including the Double Ratchet algorithm, as we...
- **Signal Android SDK** — Signal-Android is the open-source Android client for the Signal encrypted messaging platform. It provides the full messaging experience including end-to-end encrypted text messa...
- **Signal iOS SDK** — Signal-iOS is the open-source iOS client for the Signal encrypted messaging platform. It delivers end-to-end encrypted messaging, voice calls, video calls, and group communicati...
- **Signal Desktop SDK** — Signal-Desktop is the open-source desktop client for the Signal encrypted messaging platform, built with Electron and TypeScript. It provides end-to-end encrypted messaging, voi...
- **Signal Accounts API** — Account management endpoints for configuring account settings, managing capabilities, and account lifecycle operations.
- **Signal Attachments API** — Attachment handling endpoints for uploading and downloading media files associated with messages.
- **Signal Certificates API** — Certificate endpoints for retrieving delivery certificates used in sealed sender message delivery.
- **Signal Devices API** — Device management endpoints for linking, unlinking, and managing devices associated with a Signal account.
- **Signal Keys API** — Pre-key bundle management endpoints for uploading and retrieving public key material used in the Signal Protocol key exchange.
- **Signal Messages API** — Message sending and receiving endpoints for delivering encrypted messages between Signal users.
- **Signal Profiles API** — Profile management endpoints for setting and retrieving user profile information including names, avatars, and capabilities.
- **Signal Registration API** — Account registration endpoints for creating new Signal accounts via phone number verification.
- **Signal Stickers API** — Sticker pack management endpoints for uploading and retrieving sticker packs.

## Agentic access (1)

- **Signal Agentic Access** — 18 operations · 9 acting

## Security (3)

- **Signal Authentication** — http · 2 schemes
- **Signal Domain Security** — TLSv1.3 · DNSSEC · DMARC
- **Signal Vulnerability Disclosure** — security.txt · contact published

## Plans (1)

- **Signal Plans Pricing**

## Tags

Encryption, Messaging, Security, Cryptography, Open-Source, Privacy

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