Best Finance & Payments APIs in 2026

USDC issuance, custody, and payment rails. Circle Skills provide agent-native CLI and coding agent instructions. Nanopayments testnet targets sub-cent agent commerce.

Stablecoin issuance and spend API (now part of Stripe). REST SDK across multiple languages. Community MCP wrappers exist but no official one yet.

HTTP 402 payment standard for agent-to-agent pay-per-call. MCP server, CLI, TS/Python SDKs. Becoming the de facto rail for metered agent APIs.

Single MCP front door for agent payment flows with no key management and usage-based billing. YC-backed startup explicitly built because 'APIs weren't built for agents'.

Identity and stablecoin payments for agents. KYAPay is the 'Know Your Agent' checkout layer. Multi-language SDKs for Node/Python/Go.

The first banking platform built for AI agents. MCP server, CLI tool, permissioned architecture with initiator-approver workflow. Opens business bank accounts, issues corporate cards, handles payments (ACH/wire/USDC) and invoicing.

Startup business bank with MCP server (beta, read-only) for balance and transaction access. SDK, OAuth, public pricing. Account opening still requires human.

Per-agent wallets with policy engine and human approval flows. Lets AI agents pay humans and vendors under scoped spend limits.

MCP server and Acceptance Toolkit for agent checkout over the Visa network. Trusted Agent Protocol for card-scheme-backed agent payments.

MCP server exposing Mastercard APIs to agents. Supports Claude, Cursor, Copilot. Pilot with select merchants and banks.

Corporate cards, expense management, bill pay, and banking for startups via REST API.

Corporate cards, AP automation, and expense management for finance teams via REST API with OAuth 2.0.

European expense management and corporate cards. Public OAuth 2.0 API with curl examples, covering cards, expenses, receipts, and reimbursements.

Business banking, corporate cards, AP automation, and treasury for startups and mid-market. Partner API gated behind sales.

Agentic Workflow Protocol for compliant multi-step payment flows. Protocol SDK only - no MCP, no CLI yet. a16z-backed, early-access.

Corporate travel booking, expense management, and corporate cards. OAuth 2.0 REST API gated behind admin-console provisioning.