Built on Stellar · Open beta

Send money from
any phone in
Africa

Stackr turns any mobile phone into a stablecoin wallet. Your users dial a USSD code to send money, pay bills, and cash out — no app download, no internet, no smartphone required.

One REST API. You integrate it. We handle Stellar, wallets, and settlement.

Get API Key — FreeRead the Docs
Stackr USSD100%
*384#Ready
Press Dial to start a USSD session.

16

Endpoints

Full REST API

<100ms

Avg Response

USSD-grade latency

2G

Min Phone

No internet needed

~5s

Settlement

Stellar finality

How it works

From dial to settlement in three steps. No app downloads, no blockchain knowledge, no internet connection required.

01

User dials a USSD code

No app needed. The user dials *384# from any phone — feature phone, smartphone, 2G or 4G. Works offline.

02

Stackr handles everything

Wallet creation, Stellar transactions, currency conversion, fee bumping, and settlement — all in under 5 seconds.

03

Money arrives instantly

The recipient gets a confirmation SMS. Funds settle on Stellar in USDC. Cash out at any supported anchor.

Everything your users need

A complete financial toolkit accessible from any phone. Integrate once and give your users access to all of these.

Send Money by Phone Number

Users send stablecoins to any phone number. One API call handles wallet lookup, Stellar transactions, and fee bumping automatically.

Pay Bills with USDC

Airtime, data, electricity, cable TV. Users pay in stablecoins, Stackr converts and delivers to local providers instantly.

Cash In / Cash Out

Deposit local currency to get USDC. Withdraw USDC to receive mobile money. Integrated with SEP-24 anchors for compliant fiat rails.

Merchant Payments

Issue merchant codes via API. Customers pay by entering the code on USSD. Instant USDC settlement, no POS hardware needed.

Token Swaps

USDC/XLM swaps on the Stellar DEX, exposed as a simple API call. Real-time pricing, automatic path finding, slippage protection.

Auto-Managed Wallets

Every phone number gets a Stellar wallet automatically. No seed phrases, no key management for end users. Fully custodial.

Integrate in minutes

Simple RESTful API. Get your API key, make a request, and you have stablecoin payments working. No blockchain knowledge required.

# Transfer USDC between phone numbers
curl -X POST https://api.usestackr.xyz/v1/transfers \
  -H "Authorization: Bearer sk_live_abc123..." \
  -H "Content-Type: application/json" \
  -d '{
    "sender_phone": "+250781234567",
    "recipient_phone": "+250789876543",
    "amount": "10.00",
    "pin": "1234"
  }'

# Response
{
  "tx_hash": "3d8f4a2b1c9e...",
  "status": "completed",
  "fee": "0.00001"
}

Why Stackr

Transparent infrastructure you can trust and verify.

Built on Stellar

Transactions settle on the Stellar network — a public, decentralized blockchain designed for payments. Fast, cheap, and auditable.

Open Source Backend

The Stackr engine is open source. Inspect the code, audit the logic, deploy your own instance. No black boxes.

USDC Stablecoin

All balances are held in USDC — a regulated, dollar-backed stablecoin issued by Circle. No volatility risk for your users.

Built in Rust

The backend is written in Rust with Actix-web. Memory safe, zero-cost abstractions, and the performance to handle USSD latency constraints.

Architecture

From USSD dial to Stellar settlement in milliseconds. Every layer is designed for the constraints of mobile money in Africa.

User dials *384# on any phone
        │
  Telco USSD Gateway
        │
  Africa's Talking (POST /ussd/callback)
        │
  ┌─────▼──────┐
  │  actix-web  │──── IP allowlist + rate limiting (Redis)
  └─────┬──────┘
        │
  USSD State Machine (Redis session + Postgres user lookup)
        │
  ┌─────┼──────────────────┐
  │     │                  │
Stellar     Postgres        External APIs
─────────   ────────        ─────────────
TX builder  users           SEP-24 anchors
transfers   transactions    CoinGecko (rates)
swaps       anchor_orders   Airbills (bills)
trustlines  user_activity   Africa's Talking (SMS)
fee bumps   merchants

USSD latency is sacred

Sessions timeout after ~30 seconds. Every handler responds fast. Heavy operations are fire-and-forget via tokio::spawn.

Config over code

Deploy to a new country by changing env vars. Currency, anchor, and shortcode are all configurable.

Atomic state transitions

Once an order reaches a terminal state (completed/error/expired), it cannot be changed. No double-credits.

Fail safe

If a bill payment API fails after debiting USDC, the system auto-refunds. Money is never silently lost.

Ready to give your usersstablecoin payments?

Get your API key in seconds. The free tier includes 1,000 calls per month — enough to build and test a full integration.

curl https://api.usestackr.xyz/v1/health

Try it now — no API key needed

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