# DEVELOPER DOCUMENTATION

This section contains the **Timestamp** (TSA) usage reference. There is no REST or OpenAPI API; the protocol is **RFC-3161** (Time-Stamp Protocol) over HTTP.

## Contents

- **[Usage reference](/products/namirialpkiaas/timestamp/enterprise-documentation/developer-documentation/api/usage-reference)** — Full workflow with **OpenSSL** and **curl**: hash generation, timestamp request (`.tsq`), and verification (`.tsr`).


Use [GET STARTED](/products/namirialpkiaas/timestamp/enterprise-documentation/get-started/overview) for endpoints and Billing authentication.