High-volume crypto settlement rails, batch payout automation, and reconciliation pipelines — built for scale.

A payment gateway tells you a transaction was received. A settlement system tells you what every merchant is owed — and moves the money correctly, every time.

The gap between "crypto received" and "merchant paid" is where most crypto payment platforms break at scale. Transaction confirmation is the easy part. Settlement requires netting across multiple wallets and chains, applying fee structures per merchant, batching payouts to minimise gas and network fees, reconciling on-chain events against your internal ledger, and producing audit trails that satisfy your finance team. PROPELOO builds the processing infrastructure that closes this gap: idempotent settlement pipelines that handle chain reorgs, batch payout engines that optimise gas across hundreds of simultaneous withdrawals, and double-entry accounting ledgers that tie every on-chain event to a line in your books.

Crypto settlement infrastructure: the systems that sit between transaction confirmation and merchant payout.

Production settlement at scale requires correct decisions across netting logic, payout orchestration, reconciliation, and ledger integrity simultaneously.

System Layers

• Settlement Layer: Netting engine, confirmation thresholds, reorg handling, settlement finality logic per chain
• Payout Layer: Batch payout orchestration, fee deduction, gas optimisation, multi-sig disbursement
• Reconciliation Layer: On-chain event indexing, ledger matching, variance detection, break reporting
• Accounting Layer: Double-entry ledger, per-merchant position tracking, FX conversion records, audit trail
• Operations Layer: Pipeline monitoring, stuck-transaction alerting, manual override workflows, runbooks

Core Technical Capabilities

• Settlement Netting Engine

  Aggregate confirmed transactions per merchant across wallets and chains. Apply delayed settlement windows (T+1, T+2 configurable). Net positions before payout to minimise gas. Handle chain reorgs with configurable confirmation depth per network.

• Batch Payout Orchestration

  Schedule and execute bulk disbursements to hundreds of merchant wallets per settlement cycle. Gas-aware batching: group payouts into optimal transaction batches to minimise network fees. Multi-sig approval workflow for large disbursements. Retry logic with exponential backoff for failed broadcasts.

• Multi-chain Reconciliation Pipeline

  Index on-chain events (ERC-20 transfers, native transfers) against internal transaction records. Automated ledger matching with variance detection. Break report generation for finance team review. Daily reconciliation runs with alerting on unmatched items exceeding threshold.

• Double-entry Accounting Ledger

  Every settlement event recorded as a double-entry journal: debit merchant liability, credit payout. Crypto-to-fiat FX rate capture at settlement time. Per-merchant P&L positions. Exportable ledger in formats compatible with accounting systems. Full audit trail per transaction.

• Pipeline Monitoring & Alerting

  Real-time monitoring of settlement pipeline stages. Alerts on stuck transactions, failed payouts, reconciliation breaks, and abnormal settlement volumes. Manual override interface for operations team. Incident runbooks per failure mode.

• Exchange & Custody Integration

  Connect settlement engine to custodian APIs (Fireblocks, BitGo) or self-custodied hot/warm/cold wallet infrastructure. Exchange API integration for crypto-to-fiat conversion at settlement. Webhook events per settlement cycle for downstream ERP and accounting system sync.

How we approach crypto payment processing.

Every crypto payment processing project has the same fundamental challenge: translating what the business needs into software that reliably delivers it. The engineering is the easy part. The hard part is making sure the right thing is being built.

• Discovery before development

  A sprint that starts without agreed architecture and scope will spend the first three days making decisions that should have been made in discovery. Paid discovery (5-10 days) that produces architecture documentation, data model and milestone plan is not optional overhead — it is the difference between a sprint team that executes and one that debates.

  Axiom:

• Working software is the only metric

  A sprint that produces completed tickets but no deployable software has not made progress. Every sprint ends with software that can be deployed to staging and demonstrated. Velocity is measured in shipped features, not story points.

  Axiom:

• Change management over scope freeze

  Requirements change. The question is whether they are managed transparently. Every scope change is documented as a change order: what is changing, estimated effort impact, timeline adjustment. This protects both parties.

  Axiom:

• IP transfers with each milestone

  Every deliverable — code, architecture documentation, design files — transfers to the client at the milestone invoice. No ongoing PROPELOO dependency. No licence fees. The codebase is yours from day one.

  Axiom:

The decisions that define the system.

These are the questions we work through in the architecture phase.

• Build vs buy?

  Impact: Build for competitive differentiators. Buy or integrate for commodity functionality. The correct split depends on what makes your system unique.

  • Build from scratch — maximum fit, maximum time
  • Customise existing solution — faster, less precise fit
  • SaaS integration — fastest, ongoing cost
  • Hybrid — core custom, commodity components SaaS

• Monolith vs microservices?

  Impact: Start with a modular monolith. Extract services when demonstrated need justifies operational overhead.

  • Modular monolith — best default for most systems
  • Microservices — justified by team size or scaling requirements
  • Serverless — good for event-driven, spiky workloads
  • Hybrid — monolith with extracted services

• SQL vs NoSQL?

  Impact: PostgreSQL for the primary data store unless access patterns specifically require another approach.

  • PostgreSQL — ACID, flexible, correct for most applications
  • MongoDB — document model for highly variable schemas
  • DynamoDB — infinite scale, restrictive queries
  • Redis — caching and session storage

• Synchronous vs async processing?

  Impact: Async processing for operations that do not need to be in the response path. Synchronous for reads and real-time requirements.

  • Synchronous REST — simple, tight coupling
  • Async queues (SQS/BullMQ) — decoupled, resilient
  • Event-driven — loose coupling, eventual consistency
  • Hybrid — sync reads, async writes

• Authentication approach?

  Impact: Managed auth for speed to market unless compliance requirements mandate self-hosted.

  • Managed auth (Auth0/Clerk) — fastest, ongoing cost
  • JWT with refresh rotation — stateless, full control
  • Session-based — stateful, simpler revocation
  • Custom OAuth 2.0 — for providing auth to others

• Deployment infrastructure?

  Impact: ECS Fargate or Cloud Run for most applications. Kubernetes when the ecosystem provides genuine value.

  • Managed containers (ECS Fargate) — simple, right for most
  • Kubernetes — justified for complex orchestration needs
  • Serverless (Lambda) — good for event-driven, variable load
  • VPS — simple, lowest cost for predictable low traffic

What PROPELOO builds.

• Crypto Payment Processing — Production System

  Full production crypto payment processing from architecture through deployment — milestone-based delivery, automated testing, CI/CD and documentation.

• Crypto Payment Processing — MVP

  Rapid MVP of the core crypto payment processing functionality — focused scope, 8-12 week delivery, production-quality from the start.

• Crypto Payment Processing — Modernisation

  Migrate or rebuild an existing crypto payment processing system — strangler fig migration, zero-downtime deployment, data migration.

• Crypto Payment Processing — API & Integration

  Crypto payment processing API development and third-party integration — OpenAPI spec, authentication, rate limiting and developer documentation.

• Crypto Payment Processing — Audit & Review

  Architecture review of existing crypto payment processing system — technical debt assessment, security review, performance bottlenecks and remediation roadmap.

• Crypto Payment Processing — Scale-up

  Performance engineering for crypto payment processing at scale — load testing, bottleneck identification, caching strategy and infrastructure scaling.

Technology selected for the problem, not habit.

Every technology choice is justified against the specific requirements of the system.

• Backend

  Stack: Node.js (TypeScript), Go, Python, PostgreSQL, Redis

• Frontend

  Stack: React, Next.js, TypeScript, Tailwind CSS, TanStack Query

• Infrastructure

  Stack: AWS / GCP, Terraform, Docker, Kubernetes / ECS, GitHub Actions

• Quality

  Stack: Jest / Vitest, Playwright, k6 (load testing), Sentry, OpenTelemetry

• API

  Stack: REST + OpenAPI, GraphQL, WebSocket, gRPC

• Auth

  Stack: Auth0, Clerk, JWT, OAuth 2.0

Security built in, not bolted on.

Every PROPELOO engagement includes security as a standard part of delivery.

• Authentication & Authorisation

  Secure session management, RBAC at the API layer, JWT with correct expiry and rotation, OAuth 2.0 integration and audit logging for sensitive operations.

• Input Validation

  Schema validation at the API boundary, parameterised queries (no SQL injection), output encoding for XSS prevention and file upload validation.

• Secrets Management

  No secrets in source code, AWS Secrets Manager or equivalent, rotation without downtime and least-privilege IAM per service.

• Dependency Security

  Automated vulnerability scanning (Dependabot/Snyk) in CI, pinned dependency versions, no known critical CVEs in production builds.

• Data Protection

  Encryption at rest for sensitive fields, TLS 1.3 in transit, PII fields identified with appropriate access controls and retention limits.

• Threat Modelling

  STRIDE threat modelling at the architecture phase — trust boundaries, attack surface identification and risk-prioritised mitigation before implementation.

From architecture to production.

1. 01. Discovery Sprint

   Architecture, data model, technology selection, milestone plan. Deliverable: architecture document.

2. 02. Foundation Sprint

   Project scaffold, CI/CD, environments, auth, core data model.

3. 03. Core Development

   Feature development in 2-week sprints. Working software every sprint.

4. 04. Integration

   Third-party integrations, API connections, data pipeline.

5. 05. Quality & Security

   Test suite, performance testing, security review.

6. 06. Production Deployment

   Zero-downtime production deployment, monitoring, runbooks.

7. 07. Handoff

   Documentation, knowledge transfer, optional retainer.

Crypto payment processors we have shipped to production.

Three processing infrastructure builds handling enterprise payment volumes.

• Payment processing infrastructure supporting 12 chains and 40+ tokens

  Challenge: Payment service provider needed a single processing backend capable of accepting payments on 12 blockchains, normalising transaction events across chains into a unified payment status model, and routing settlements to the correct merchant account.

  Architecture: Per-chain listener nodes publishing to a unified Kafka topic, normalisation layer translating chain-specific event formats to payment schema, idempotent payment state machine, multi-signature settlement batching.

  Outcome: 12 chains live, 40+ tokens supported, 400,000 transactions processed monthly, 99.97% successful settlement rate.

• USDC payment processor handling 8,000 transactions/hour for marketplace

  Challenge: Marketplace client needed a USDC payment processor capable of handling bursts of 8,000 transactions/hour during flash sales with instant payment confirmation and automated seller payouts.

  Architecture: Circle Programmable Wallets for buyer/seller accounts, event-driven payout engine triggered on confirmation, batched seller payouts every 15 minutes, Redis-based idempotency keys preventing double-processing.

  Outcome: Peak 8,400 transactions/hour handled without degradation, 99.99% payout accuracy, median confirmation-to-payout time 8 minutes.

• Corporate treasury payment system for stablecoin payroll and vendor payments

  Challenge: Enterprise client with 800 contractors across 40 countries needed a stablecoin payroll system — CSV upload of payment amounts, bulk USDC transfers, per-recipient tax documentation, and CFO-grade reporting.

  Architecture: CSV ingestion pipeline with validation, Fireblocks batch transaction API for bulk transfers, per-recipient wallet provisioning, PDF payslip generation, multi-currency conversion for local currency display.

  Outcome: 800 contractors paid monthly in USDC, processing time reduced from 5 days (SWIFT) to 4 hours, 60% cost reduction in payment fees.

Frequently Asked Questions