Top Picks
Stripe remains the default starting point for developer-facing payment infrastructure, and for good reason. Its documentation is thorough, its sandbox environment closely mirrors production behavior, and its API design reflects years of feedback from developers who have built on it. For teams embedding checkout flows, subscription billing, or marketplace payments, Stripe's breadth of supported use cases means you're unlikely to outgrow it quickly. It handles ACH transfers alongside card payments, which matters if you're building for B2B clients. Best for: teams that want to move fast, need solid documentation, and are building primarily for the US and major international markets.
Plaid is the practical standard for bank account linking and financial data aggregation in the US. If your application needs to verify bank accounts, pull transaction history, or check balances, Plaid's API coverage and institution breadth are difficult to match domestically. The developer experience is consistent, and the Link UI component handles the end-user authentication flow without you needing to build it yourself. Plaid has expanded beyond basic account linking into identity verification and income verification — useful if your product involves underwriting or KYC flows. Best for: apps that need to connect to users' bank accounts, fintech lending platforms, and personal finance tools.
Adyen is built for companies that have outgrown simpler payment processors or need global coverage from day one. It offers a unified platform for online, in-person, and embedded payments, which matters if your product spans channels. The API is well-documented, but Adyen's setup and approval process is more involved than Stripe's — expect a longer onboarding cycle and minimum volume requirements. For developers building platforms where merchants need to accept payments (marketplace or SaaS with billing), Adyen's for platforms product gives you more control over fund flows than many alternatives. Best for: larger teams, global products, and platforms handling payments on behalf of sub-merchants.
Marqeta is the dominant modern card issuing platform. If your product involves issuing physical or virtual cards — whether for employee spending, consumer wallets, or B2B payment products — Marqeta's API gives you granular control over authorization logic, spending controls, and transaction data. The just-in-time funding model is particularly useful for fintech products that need to control when and how cards are funded. Marqeta is not a simple integration; plan for compliance and program management overhead. Best for: fintech teams building consumer or commercial card programs, expense management products, and gig economy platforms with worker payment needs.
Unit offers embedded banking infrastructure — bank accounts, cards, and payments — as a single API. For teams building a financial product that needs to hold funds, move money, and issue cards under a branded experience, Unit abstracts much of the banking-as-a-service complexity. The developer experience is relatively clean, and Unit's compliance and banking partner relationships are bundled into the offering. This reduces the integration surface compared to assembling your own stack from a sponsor bank, card network, and processor. Best for: fintech startups building neobank-style products, vertical SaaS companies adding financial accounts, and teams that want embedded banking without managing multiple vendor relationships.
Codat specializes in connecting to small business accounting and banking data — think QuickBooks, Xero, Sage, and major bank feeds — through a single normalized API. If your product needs to read or write financial data from the accounting systems your business customers already use, Codat removes the need to build and maintain individual integrations. The data models are standardized across sources, which simplifies your application logic considerably. Managing accounts receivable data from multiple accounting platforms becomes tractable when you're not mapping each source's schema individually. Best for: B2B fintech products, lending platforms that need financial data from SMB applicants, and SaaS tools that want to sync with customers' accounting systems.
Buyer's Guide
The most important decision in this space is not which single tool to use, but which category of tool you actually need. These six tools solve meaningfully different problems.
Payment processing vs. embedded banking vs. financial data are three distinct layers. A developer building a checkout flow needs a payment processor like Stripe or Adyen. A developer building a product where users hold balances and make transfers needs embedded banking infrastructure like Unit. A developer building a product that analyzes or acts on users' existing financial data needs aggregation tools like Plaid or Codat. Many products need more than one layer, but conflating them leads to choosing the wrong primary tool.
Evaluate sandbox quality before committing. The difference between a good and a mediocre financial API is often most visible in the sandbox. Can you simulate edge cases — failed payments, bank account errors, authorization declines? Does the sandbox behave consistently with production? This is worth testing explicitly during your evaluation, not assuming.
Compliance and program management overhead varies significantly. Stripe and Plaid have relatively streamlined onboarding for standard use cases. Marqeta, Adyen, and Unit involve more compliance review — particularly if you're issuing cards or holding customer funds. Factor this into your go-to-market timeline. Some programs require sponsored bank relationships, and the approval process takes weeks, not days.
Volume and pricing thresholds matter. Several of these platforms have minimum volume requirements or pricing structures that favor scale. Adyen, for instance, is generally better suited to companies with meaningful transaction volume. Marqeta's economics improve at scale. If you're in early-stage development, understand which tools will work with you before you've reached scale and which expect it.
One practical note for fintech founders: developers building financial products often end up needing business banking for their own company too. If you're evaluating banking options for the company itself alongside your product stack, see our Brex vs. Mercury comparison — the needs of your product infrastructure and your company's own banking are worth evaluating separately rather than defaulting to one vendor for both.
Global vs. US-first is a real fork in the road. Plaid's coverage is largely US-centric (with some international expansion). Stripe has broad global coverage. Adyen was built for global from the start. If your product will launch internationally or needs to handle non-US bank data, verify coverage for your specific target markets during evaluation rather than assuming it exists.
Pricing Reality Check
Financial infrastructure pricing is often not straightforward, and the sticker price rarely reflects the total cost of building on a platform.
Payment processors typically charge per-transaction fees that look small in isolation but compound quickly at scale. Interchange-plus pricing can be more predictable than flat-rate pricing for high-volume products, but the comparison requires understanding your actual transaction mix. Watch for fees on specific payment methods — ACH, international cards, and certain card types often carry additional charges beyond the headline rate.
Bank data aggregation platforms like Plaid typically charge per API call or per connected account, and pricing can escalate as your user base grows. Understand the pricing model before you hit scale — what works at a thousand users may look very different at a hundred thousand.
Card issuing platforms typically charge a combination of program fees, per-card fees, and transaction fees. The full economics of a card program include not just the platform fee but interchange revenue sharing arrangements, which vary by platform and program type. Some platforms pass through interchange; others retain it. This difference can be material to your product's unit economics.
Embedded banking platforms often bundle multiple services, which can obscure where costs are actually coming from. When evaluating these platforms, model out the expected cost for specific transaction types — inbound transfers, outbound transfers, card transactions — rather than relying on an overall estimate.
Financial data connector platforms like Codat typically charge based on the number of connected companies or API calls. If your product's usage grows with your customer count, model this cost as a variable that scales with your business, not a fixed infrastructure line item.
