Regulated financial infrastructure · v2026.7

Move money.Without the friction.

Global payment infrastructure for moving, settling and managing money across fiat, cards and stablecoins.

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PCI DSS Ready

SOC 2 Type II

ISO 27001

GDPR

Hostra

Virtual Debit Card

•••• •••• •••• ••••

Valid thru

••/••

Cardholder

HOSTRA CARDHOLDER

USDT · USDC

Settlement assets

7

Supported networks

1.5%

Platform fee

12

RBAC API scopes

Virtual cards

Issue your virtual card in seconds.

Hostra issues branded virtual debit cards on top of the same settlement core. Add them to Apple Wallet or Google Wallet and pay anywhere the network is accepted.

Hostra

Virtual Debit Card

•••• •••• •••• ••••

Valid thru

••/••

Cardholder

HOSTRA CARDHOLDER

Instant issuing

A card is created and ready to use immediately — no plastic, no shipping, no branch visit.

Apple Wallet ready

Provision the card into Apple Wallet and pay with the device the cardholder already carries.

Google Wallet ready

The same card provisions into Google Wallet, with one card record behind both surfaces.

Issue Virtual Card

Every card lives in the Hostra cabinet.

Balances, card state and authorizations sit next to settlements and the audit chain you already run.

Open the cabinet

Card overview

active

Available

$4,820.00

Card

•••• ••••

Wallet

Apple · Google

Northwind Labs
card · approved
−$128.40
Apple Services
card · approved
−$9.99
Top-up
settlement · succeeded
+$1,500.00

Hostra payment card moving through a digital settlement network

Money movement

One continuous path from card to network.

Value never sits in an unexplained state. Every stage of a Hostra transfer is a recorded, verifiable step.

01 · Card

The card is the entry point

A customer card starts the transfer. Hostra never stores raw card data — tokenization happens at the processor.

Why Hostra exists

Payments break at the edges. We rebuilt the core.

01The problem

Modern payment infrastructure fails under retries, partial failures and duplicate delivery.

02Our approach

Hostra was designed around deterministic state transitions instead of best-effort recovery.

03The guarantee

Every settlement intent produces at most one ledger effect.

Engineering proof

Six properties the engine holds under load

Not marketing claims. Invariants enforced in code, verified in tests, observed in production.

01

Idempotency by construction

Every settlement intent carries a client-side key. Duplicate submits collapse to a single ledger effect — safe to retry from any layer of your stack.

02

Deterministic state transitions

State is a pure fold over an append-only journal. Two nodes at the same offset compute the same hash, byte-for-byte.

03

Append-only ledger

Double-entry, hash-chained postings. Corrections are compensating entries — the history is never rewritten.

04

Lease-based ownership

Each partition is owned by exactly one worker via a fenced lease. A stale token cannot commit, so network partitions never produce split-brain.

05

Retry orchestration

Backoff, jitter, budget and dead-letter routing are first-class objects — declared per counterparty, inspected in the control plane.

06

Verifiable audit trail

Merkle root emitted per epoch. External auditors verify the ledger end-to-end without trusting the operator.

Idempotency-Key

Exactly-once mutations

HMAC webhooks

Signed, retried, dead-lettered

RBAC scopes

Merchant-scoped M2M keys

RFC 7807

Machine-readable errors

Hash-chained audit

Append-only history

Tokenized cards

No PAN or CVV stored

Platform

Every financial primitive. One platform.

Composable building blocks engineered for regulated money movement — from ledger to settlement.

Card-to-crypto transfers

Charge a tokenized card and disburse USDT or USDC as one composite saga with automatic compensation.

Server-side quotes

Rate, platform fee and network fee are priced by the engine before a transfer is ever created.

Settlement & ledger

Every intent moves through an explicit lifecycle and lands as double-entry postings you can reconcile.

Virtual cards

Issue cards, inspect state and reveal secure details through a short-lived, scoped session.

Wallet balances

Read fiat, card and crypto balances in minor units from a single scoped endpoint.

HMAC webhooks

Signed delivery with retry, backoff and dead-letter routing for every state change.

Receipts & ISO 20022

Download the PDF receipt, the JSON payload and — where the flow produces one — the ISO 20022 message.

Devices & sessions

Enrolled devices and sessions are listed and revocable from the cabinet.

Audit & compliance

Hash-chained audit events and compliance records for every account-level action.

Products

Ship faster with modular products

Adopt what you need today. Extend without re-platforming tomorrow.

01POST /v1/quotes
Quote
The engine prices the rate, platform fee and network fee and returns a quote you can show before anything moves.
02Tokenized card
Authorize
The card is tokenized by the payment provider. Hostra never receives or stores a PAN or CVV.
03POST /v1/transfers
Transfer
The transfer is created with an Idempotency-Key, so retries from any layer collapse into one effect.
04GET /v1/transfers/{id}
Settle
The saga advances through its lifecycle. Status is read from the engine — never simulated in the browser.
05Double-entry postings
Reconcile
Each terminal state writes balanced postings that reconcile against the settlement record.
06GET /v1/receipts/{uetr}
Receipt
A PDF receipt and JSON payload are produced for the completed operation and are downloadable in the cabinet.

Solutions

Financial infrastructure for every model

From banks modernizing their core to fintechs building from scratch — one platform, one API surface.

For Banks

Modernize your core without replacing it

Wrap legacy cores with a modern ledger, real-time rails and a developer-first API surface.

Talk to us

For Fintech

Go to market in weeks, not years

Accounts, payments, treasury, compliance and reporting — as composable, production-grade primitives.

Talk to us

For PSPs

Run acquiring and payouts at scale

Intelligent routing, adaptive retries, split payouts and merchant onboarding on a single control plane.

Talk to us

For Enterprises

Embed regulated money movement

Global money movement, virtual accounts and treasury automation embedded into your products.

Talk to us

For Developers

APIs engineered like software, not banking

A REST API described by OpenAPI 3.0, HMAC-signed webhooks, M2M keys with RBAC scopes and runnable cURL examples.

Talk to us

Developer Experience

Made for engineers who ship money

A REST API described by OpenAPI 3.0, HMAC-signed webhooks and M2M keys with RBAC scopes — with docs your team will actually read.

REST

OpenAPI 3.0

7

Networks

12

RBAC scopes

Stack

Go 1.25

Runtime

PostgreSQL

Datastore (pgx v5)

Redis

Cache (go-redis v9)

RabbitMQ

Queue (amqp091)

Docker

Containerized

OpenTelemetry

Tracing

HMAC-SHA256 signed webhooks with retry, backoff and dead-letter. M2M API keys with RBAC scopes. Machine-readable API description at api.hostracore.com/llms.txt.

api.hostracore.com / v1

curl -X POST https://api.hostracore.com/v1/transfers \
  -H "Authorization: Bearer $HOSTRA_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "flow": "card_to_crypto",
    "quote_id": "q_...",
    "card_pm": "pm_card_visa",
    "wallet": "TXaZ9wDeEVnH4m7u5gK3PvQr8sT6uN2mWp",
    "network": "tron",
    "asset": "USDT"
  }'

FAQ

Frequently asked questions

Direct answers about the settlement engine, the card_to_crypto saga and integrating with the production API.

What is HostraCore?

HostraCore is a payment settlement engine with a double-entry ledger and exactly-once semantics.

What problems does HostraCore solve?

HostraCore solves the exactly-once problem for payments: every settlement intent survives any failure and executes exactly once — never zero, never twice.

How does the settlement engine work?

Settlement intents are durable records with a lifecycle (pending → in_flight → succeeded/failed/reversed). A single worker holds an exclusive lease at any time. Terminal commit uses compare-and-set with a fencing token to prevent ABA errors.

How do I integrate with the HostraCore API?

Register at POST /v1/auth/m2m/register to get an API key with RBAC scopes. Use POST /v1/quotes for a server-side quote, then POST /v1/transfers to create a card_to_crypto saga.

How does merchant onboarding work?

Self-service. POST /v1/auth/m2m/register creates a merchant and its first API key. Human signup at POST /v1/auth/register creates an owned merchant with active status.

What blockchains are supported?

Tron, Ethereum, Polygon and BSC. Assets: USDT and USDC.

What is card_to_crypto?

A composite saga: leg 1 charges a card via Stripe, leg 2 disburses USDT or USDC on-chain. If leg 2 fails, the saga compensates by refunding leg 1.

How does HostraCore ensure exactly-once?

Terminal CAS commit, lease ownership with fencing tokens, a transactional outbox and query-before-retry.

Is HostraCore PCI compliant?

HostraCore reduces PCI scope by working only with Stripe tokens and never storing PAN or CVV.

Who is the architect of HostraCore?

Ildar Lykmanov (Ильдар Лукманов), machine learning engineer and payment systems architect.

Enterprise

Trusted by teams moving regulated money

Security posture, availability guarantees and observability built for banks and enterprise fintech.

Tokenized cards

PAN and CVV never reach Hostra; secure details are short-lived and scoped.

Scoped M2M keys

Merchant-scoped API keys with RBAC scopes, shown once at creation.

Observability

OpenTelemetry tracing plus public health and version endpoints.

Audit trail

Hash-chained audit events for every state change in the engine.

Build regulated financial infrastructure with Hostra

Talk to our team about your platform, or explore the developer documentation.

Request Demo Try the live demo

7

Networks

REST

OpenAPI 3.0

12

Scopes