# Vault12 Zax Cryptographic Relay API

**Canonical:** https://apis.io/apis/vault12/vault12-zax-cryptographic-relay-api/  
**Provider:** Vault12 — https://apis.io/providers/vault12/  
**Base URL:** https://zt.vault12.com  
**Documentation:** https://github.com/vault12/zax

Vault12 Zax Cryptographic Relay API is published by [Vault12](https://apis.io/providers/vault12/) on the [APIs.io](https://apis.io/) network. Tagged areas include Relay, Cryptography, Messaging, and File Exchange. The published artifact set on APIs.io includes API documentation and an API reference.

Open-source NaCl-based cryptographic relay operated as asynchronous "dead drops" for end-to-end-encrypted device-to-device communication. Clients establish anonymous session keys via a proof-of-work handshake (POST /start_session, /verify_session) and then post encrypted commands to /command — upload, count, download, messageStatus, delete, plus the Zax 2.0 file-command family (startFileUpload, uploadFileChunk, downloadFileChunk, fileStatus, deleteFile). Vault12 maintains a public test relay with 30-minute message expiration.

## Machine-readable artifacts (5)

- **Documentation** — https://github.com/vault12/zax
- **APIReference** — https://s3-us-west-1.amazonaws.com/vault12/crypto_relay.pdf
- **SourceCode** — https://github.com/vault12/zax
- **Sandbox** — https://zt.vault12.com
- **APIsJSON** — https://raw.githubusercontent.com/api-evangelist/vault12/refs/heads/main/apis.yml

## Tags

Relay, Cryptography, Messaging, File Exchange

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/vault12/vault12-zax-cryptographic-relay-api/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/vault12/.