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BB Dev Team
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Most companies integrate with existing payment providers (Stripe, Adyen, PayPal).
But what if you need to build your own payment provider?
We went down this path, and it turned out to be one of the hardest technical challenges weβve faced.
Hereβs a breakdown of the complexity that comes with building a system that moves money reliably and securely at scale.
What you can expect: no standardized, old interface, many special regulations and lots and lots of testing
A payment provider isnβt one API β itβs many:
Every integration has different standards, formats, and SLAs.
Your system becomes the glue between dozens of protocols.
Recurring payments are much harder than one-time transactions.
We ended up building a dedicated billing microservice to handle this logic.
Payment data is the most sensitive data you can hold.
We designed a segmented database architecture:
A payment provider must detect and prevent fraud in real time.
Every millisecond counts β fraud detection must run inline with transactions.
Payments are state machines β and distributed systems love to break.
We implemented a double-entry ledger with immutable transaction logs to guarantee reconciliation.
Your clients (merchants) expect:
Building a developer-friendly product requires as much effort as the core payment logic itself.
The system must be designed for 99.999% availability, because downtime means lost money.
Building a payment provider is not βjust another API.β
Itβs a network of integrations, a secure vault, a billing engine, a fraud system, and a financial ledger β all in one.
While integrating Stripe takes a few hours, building Stripe takes years.
For us, this has been one of the most demanding engineering challenges β but also one of the most rewarding.
It forces you to think about:
And in the end, you realize: Money never sleeps β and neither can your payment system.
Continue reading...
But what if you need to build your own payment provider?
We went down this path, and it turned out to be one of the hardest technical challenges weβve faced.
Hereβs a breakdown of the complexity that comes with building a system that moves money reliably and securely at scale.
What you can expect: no standardized, old interface, many special regulations and lots and lots of testing
1. Multi-Layered Interfaces
A payment provider isnβt one API β itβs many:
- Card Networks (Visa, Mastercard, Amex): Integration with different protocols, settlement, and reconciliation.
- Alternative Payments: Bank transfers, wallets, crypto, vouchers.
- Merchant Interfaces: APIs and dashboards for external clients.
- Regulatory APIs: KYC, AML, fraud monitoring.
Every integration has different standards, formats, and SLAs.
Your system becomes the glue between dozens of protocols.
2. Subscription & Billing Management
Recurring payments are much harder than one-time transactions.
- Subscriptions: Track cycles, retries, upgrades, downgrades, cancellations.
- Invoices: Generate legal documents in multiple jurisdictions.
- Prorations: Handle when a user changes a plan mid-cycle.
- Dunning Logic: Retry failed payments intelligently without spamming banks.
- Multiple Currencies: Exchange rates, rounding rules, settlement differences.
We ended up building a dedicated billing microservice to handle this logic.
3. Data Storage & Security
Payment data is the most sensitive data you can hold.
- PCI DSS Compliance: Storage of cardholder data requires tokenization and encryption.
- Vaults: Sensitive card data must never touch the core DB β itβs stored in isolated vault services.
- Encryption-at-Rest + In-Transit: All data is encrypted multiple times.
- Minimal Retention: Store as little as legally possible.
- Audit Trails: Every read/write must be logged and immutable.
We designed a segmented database architecture:
- Encrypted vault DB for card data.
- Transaction DB for operational data.
- Analytics DB for reporting.
4. Fraud Detection & Risk Management
A payment provider must detect and prevent fraud in real time.
- Velocity Checks: Too many transactions in short time.
- Behavioral Analysis: Unusual patterns compared to history.
- Device Fingerprinting: Identify suspicious devices.
- Machine Learning Models: Risk scoring on each transaction.
Every millisecond counts β fraud detection must run inline with transactions.
5. Reliability & Idempotency
Payments are state machines β and distributed systems love to break.
- Idempotency Keys: Critical to prevent duplicate charges when retries happen.
- Ledger System: Every transaction must be immutable, reversible only with compensating entries.
- Consistency: Even under failure, your books must reconcile to the cent.
- Partial Failures: One bank might succeed, another fails β the system must handle rollback scenarios gracefully.
We implemented a double-entry ledger with immutable transaction logs to guarantee reconciliation.
6. Developer Experience
Your clients (merchants) expect:
- Clean REST + Webhook APIs.
- SDKs in multiple languages.
- Sandbox Mode for testing.
- Real-Time Dashboard for transactions and disputes.
Building a developer-friendly product requires as much effort as the core payment logic itself.
7. Scaling & Compliance
- High Throughput: Payments must clear in milliseconds, even under peak load.
- Global Scale: Data residency laws β different storage per region.
- Compliance: PSD2, PCI DSS, GDPR β each with strict requirements.
- Disaster Recovery: Active-active datacenters, multi-region replication.
The system must be designed for 99.999% availability, because downtime means lost money.
Conclusion
Building a payment provider is not βjust another API.β
Itβs a network of integrations, a secure vault, a billing engine, a fraud system, and a financial ledger β all in one.
While integrating Stripe takes a few hours, building Stripe takes years.
For us, this has been one of the most demanding engineering challenges β but also one of the most rewarding.
It forces you to think about:
- Security by design.
- Reliability in distributed systems.
- Performance at financial scale.
And in the end, you realize: Money never sleeps β and neither can your payment system.
Continue reading...
