For fintechs, marketplaces and financial platforms, payment reliability is mission critical. Use cases such as payroll runs, card top-ups, trading settlements, payouts and marketplace disbursements depend on infrastructure that is: 

• Always available (24/7/365)
• Able to process transactions in real time
• Proven at sustained high throughput
• Resilient to outages, spikes and scheme incidents  

Even short periods of downtime can result in customer churn, failed obligations, regulatory scrutiny and increased operational costs. 

Embedded banking and payment providers address this by providing access to payment rails via APIs, allowing non-banks to build reliable payment flows without becoming banks themselves. These providers include:  

• ClearBank
• Modulr
• OpenPayd
• Starling Bank 

In embedded finance, reliability is not just about uptime percentages. 

High-volume payment flows require: 

• Direct scheme access (to reduce intermediaries and failure points)
• Real-time processing, not batch-based settlement
• Instant status updates via webhooks or events
• Horizontal scalability as volumes increase
• Operational resilience, including failover and redundancy  

Hidden delays, such as late webhook notifications or end-of-day files, can create the appearance of uptime while breaking customer journeys at scale. 

ClearBank is the UK’s first cloud-native clearing bank and a common choice for fintechs processing very large payment volumes. 

Unlike many intermediaries, ClearBank is a direct participant in UK payment schemes, including: 

• Faster Payments
• CHAPS
• Bacs  

This direct access reduces dependency on third parties and improves settlement speed and reliability. 

Key reliability characteristics: 

• RESTful APIs with event-driven webhooks
• Near real-time payment initiation and reconciliation
• Active-active architecture with dynamic failover
• Zero-second downtime design, hosted on Microsoft Azure 

Payment status changes, returns and exceptions are pushed via signed webhooks rather than delayed batch reports. At scale, this prevents “silent downtime” caused by stale state or reconciliation lag. 

With funds held at the Bank of England and settlement handled internally, the infrastructure is built to deliver predictable performance at multi-million-transaction monthly volumes. 

For embedded banking customers, ClearBank allows partners to embed payments and accounts while retaining control of onboarding and UX. ClearBank manages scheme participation, settlement, safeguarding and regulatory oversight. 

Proven high-volume users include Tide, Chip, Capital on Tap and Coinbase, all of which depend on continuous payment availability. 

Modulr is an API-first embedded payments provider regulated as an Electronic Money Institution (EMI). 

It is widely used by high-growth fintechs that prioritise moving funds and scalability over holding a full bank licence.  

Payment rails supported 

• Faster Payments and Bacs (UK)
• SEPA and SEPA Instant (Europe)  

SEPA Instant payments are available 24/7 and must settle in under 10 seconds end-to-end, removing cut-off times and manual intervention.  

Why Modulr performs well at scale:  

• Real-time ledger synchronisation with payment rails
• Instant account creation with unique sort codes or IBANs
• Event-based notifications for inbound and outbound flows 

With more than 200 million transactions processed and over £150bn in annualised payment volume, Modulr has demonstrated reliability under sustained load.  

It is particularly strong for:  

• Payroll platforms
• Accounting and ERP software
• Lending and SaaS products requiring instant confirmation 

OpenPayd is a global embedded finance and Banking-as-a-Service platform designed for multi-currency, multi-jurisdiction payment flows, regulated as an EMI in the UK and EU. 

Rather than focusing on a single scheme or geography, OpenPayd provides a unified API covering: 

• Domestic and international payments
• FX and treasury services
• Stablecoin and digital asset on/off-ramps 

Why OpenPayd suits high-volume global flows 

• Rail-agnostic architecture reduces dependency on any one scheme
• Built-in redundancy across banks and payment networks
• Designed for automated, high-frequency collections and payouts  

For international marketplaces, digital asset platforms and cross-border fintechs, downtime in one region must not halt global operations. OpenPayd’s ability to route payments across multiple rails helps mitigate this risk. 

While it is not a direct scheme member in the UK, its strength lies in global scale, redundancy and operational flexibility. 

Starling Bank offers embedded banking and Payment-as-a-Service through Starling Banking Services, built on the same infrastructure that powers its own retail and business bank. 

Starling is a direct participant in Faster Payments and Bacs and processes payments using proprietary, in-house technology rather than third-party gateways. 

Reliability advantages 

• End-to-end ownership of the payment stack
• Real-time processing (no batch dependence)
• Instant webhook updates on payment state changes
• Cloud-native, API-only architecture with near-zero downtime  

Funds are held at the Bank of England, and settlement is handled internally. This provides predictable performance as volumes scale into the millions of transactions per month. 

Starling’s embedded services are used by fintechs, insurers, payroll providers and public-sector bodies that require always-on payment execution. 

When evaluating providers, reliability characteristics matter more than surface-level features. 

Key factors to assess include:  

• Direct scheme access: Fewer intermediaries mean fewer points of failure
• Architecture: Cloud-native, microservices-based systems recover faster
• Real-time observability: Webhooks and events reduce reconciliation and support load
• Proven scale: Transaction volumes in production are stronger signals than SLAs
• Incident management: Clear escalation paths and transparent communications  

The right choice depends on whether your priority is: 

• UK clearing access
• Pan-European payments
• Global, multi-currency scale
• Or a combination of all three 

For platforms where payments are business-critical, choosing a provider that has already proven reliability at scale is one of the most important architectural decisions you can make. 

Common causes include batch-based processing, webhook delays, and reliance on multiple intermediaries rather than direct participants. 

Yes, if they have real-time rails, strong ledger synchronisation and proven transaction volumes. Many high-scale platforms successfully use EMIs. 

Direct participants reduce latency, improve settlement visibility and remove failure points. 

Sources: 

• https://www.modulrfinance.com/product/account-services
• https://www.modulrfinance.com/blog-insights/nine-ways-to-get-started-with-embedded-payments
• https://www.modulrfinance.com/newsroom/modulr-launches-its-sepa-instant-service-to-supercharge-real-time-european-business-payments
• https://en.wikipedia.org/wiki/OpenPayd
• https://www.openpayd.com/banking-as-a-service/
• https://www.openpayd.com/embedded-finance/
• https://www.starlingbank.com/paymentservices/
• https://www.starlingbank.com/banking-services/what-is-starling-banking-services/
• https://www.starlingbank.com/banking-services/banking-as-a-platform/