If unlimited virtual card issuance through an API is a hard requirement, I’d separate the market into two categories: expense management platforms with built-in card issuance, and card-issuing infrastructure that lets you build your own expense management workflows.
The key distinction is that a vendor may support creating cards through an API without actually offering unlimited issuance under its commercial agreement. You’ll want confirmation of both the technical limits and any contractual caps or per-card fees.
Best options to evaluate
1. 
Lithic
(Strongest match for unlimited issuance)
Lithic explicitly advertises unlimited virtual card issuance, alongside an API-first platform, granular spending controls, real-time transaction data, and webhooks. It also offers expense-management infrastructure.
Best for: High-volume, automated card creation where API flexibility matters more than having a complete, off-the-shelf finance suite.
Official expense management offering · API documentation 【turn478013search7】【turn478013search2】
2. 
Ramp
Ramp combines corporate cards, expense management, accounts payable, and API-based automation. Its API supports programmatic virtual card creation, including fund-backed cards for vendor payments and other backend workflows.
Best for: A company that wants a full expense-management platform rather than building its own.
Verify: Whether your specific use case permits unlimited card creation, what API rate limits apply, and whether there are plan-specific card caps.
Virtual Cards API documentation 【turn478013search8】
3. 
Brex
Brex provides APIs for virtual card creation, spend limits, expenses, and transaction data. Its purchasing cards have no stated per-user card count limit in its card documentation.
Important limitation: Brex documents a default API rate limit of 5,000 cards created per 24 hours. Higher-volume needs may be discussed with support, so this is not an unlimited-throughput guarantee.
Best for: Teams wanting integrated corporate spend management with automated card issuance at moderate or negotiated high volumes.
Brex API · API rate limits 【turn973389search0】【turn973389search1】【turn973389search10】
4. 
Stripe Issuing
Stripe Issuing lets you create virtual cards through an API, configure spending limits and merchant restrictions, and monitor transactions. It is issuing infrastructure rather than a complete expense-management application.
Best for: Organizations already using Stripe or willing to build expense workflows around its APIs.
Verify: Account-specific issuance limits, pricing at your expected card volume, and whether your business qualifies for the required issuing program.
Official product page · Issuing documentation and support 【turn973389search7】【turn973389search5】
5. 
Marqeta
Marqeta offers virtual and physical card APIs, spend controls, transaction authorization, and just-in-time funding. It is designed for businesses building or embedding card-powered spending products.
Best for: Enterprise-scale or customized card programs where you need extensive control over the issuing experience.
Verify: Card-volume commitments, implementation requirements, and commercial limits with its sales team.
Expense management solutions · Developer portal 【turn478013search3】【turn478013search13】
How I would shortlist them
The main trade-off is that Lithic, Stripe Issuing, and Marqeta are more infrastructure-oriented. You may need to build or integrate your own expense reporting, accounting, approvals, and reconciliation workflows. Ramp and Brex provide more of that functionality out of the box.
Questions to ask vendors before committing
- Is there a hard maximum on active cards, total cards created, or cards per user, entity, or account?
- What is the maximum card-creation API throughput per minute and per day?
- Can we issue a unique virtual card automatically for every transaction, vendor, subscription, or purchase order?
- Are there per-card issuance, active-card, transaction, or monthly platform fees?
- Can we create and terminate cards programmatically, with real-time spend controls and transaction webhooks?
One important distinction: Unlimited card issuance does not mean unlimited spending capacity. Funding arrangements, underwriting, account balances, fraud controls, and API rate limits can still constrain the program.
To narrow this to the best two or three options
The most important question is: What do you need the virtual cards for?
1. Primary use case
Employee expenses and corporate purchasing
Automated payments — unique cards for vendors, subscriptions, or each transaction
Issuing cards to customers through our own software or platform
A combination of employee expenses and automated payments
2. Approximate issuance volume
Up to 1,000 cards per month
1,000–10,000 cards per month
10,000–100,000 cards per month
More than 100,000 cards per month
3. Preferred solution
Complete expense management software with minimal development
API-first platform; we're comfortable building workflows
Open to either approach
4. Where will the cards be issued?
United States only
Multiple countries
[Find the best-fit vendors]
