Documentation

Everything you need to integrate Stackr's stablecoin payment API into your application.

Start here

Quickstart

Get your API key and make your first request in three steps.

API Reference

All 17 endpoints with curl examples, error codes, and payloads.

Developer Guide

USSD protocol, wallet system, Stellar integration, and how it all connects.

Security

How we protect user data, keys, and funds. Best practices for your integration.

How Stackr works

Stackr is a hosted API that handles stablecoin payments over USSD. You call our REST API from your backend — we handle wallet management, Stellar transactions, and USSD session state.

Your App                     Stackr API                    Stellar Network
   │                             │                              │
   ├── POST /v1/transfers ──────>│                              │
   │   (sender, recipient, amt)  │── build + sign tx ──────────>│
   │                             │<── tx_hash ─────────────────│
   │<── { tx_hash, status } ─────│                              │
   │                             │                              │

   Your app never touches Stellar directly.
   We handle wallets, fees, signing, and broadcasting.

Key concepts

API Keys

Authenticate every request with your secret key in the Authorization header. Get keys from your dashboard. Test keys (sk_test_...) work on testnet; live keys (sk_live_...) work on mainnet.

Phone-based wallets

Every phone number automatically gets a Stellar wallet. No setup needed from your users. Wallets are created on first use and managed entirely by Stackr.

Idempotency

All money-movement endpoints are idempotent. If a request times out, retry safely — duplicate transactions are impossible. The system uses Redis-backed idempotency keys internally.

USSD integration

If you want end users to interact via USSD menus (dial *384#), point your Africa's Talking callback URL to Stackr. Otherwise, use the REST API directly from your app.

Rate limits

API calls are rate-limited per key. Free tier: 60 req/min. Pro: 300 req/min. Enterprise: custom. Exceeding the limit returns 429 Too Many Requests.

Works with any language

Stackr is a standard REST API. No SDK required — use curl, fetch, requests, or any HTTP client.

JavaScript

Python

Ruby

PHP

Rust

Ready to start?

Head to the Quickstart guide to get your API key and make your first request.

Get Started