Slash API: Issue and Control Cards

Overview

Slash's API provides programmatic access to create, manage, and control cards across your organization. You can issue virtual cards instantly, set spending limits, restrict merchant categories, and pause or close cards — all through API calls.

Key Concepts

• Cards draw from account balances. Slash cards are debit or charge cards, not prepaid cards. Each card is tied to an account (or virtual account) and spends from that account's balance.
• Spending constraints control how cards are used. You can set periodic spending limits (daily, weekly, monthly, yearly), per-transaction size limits, and restrict which merchants or countries a card can be used at.
• Card groups let you apply shared spending rules to multiple cards at once, instead of configuring each card individually.

Creating a Virtual Card

To create a new virtual card, send a POST request to /card. You'll need to provide a name for the card and set the type to virtual.

If you're authenticating with an API key, the card is created under your default commercial account automatically. You can also specify a virtualAccountId to associate the card with a particular virtual account, or a cardGroupId to add it to an existing card group right away.

You can also create single-use cards by setting isSingleUse to true. These cards automatically close after a single authorization attempt — useful for one-time vendor payments.

Viewing Card Details

To retrieve a list of all your cards, use GET /card. To get details for a specific card, use GET /card/{cardId}.

By default, the full card number and CVV are not included in the response. To retrieve sensitive card details, add ?include_pan=true to your request:

GET /card/{cardId}?include_pan=true

Setting Spending Limits

You can control how much a card can spend by updating its spending constraint via PATCH /card/{cardId}. The spending constraint supports:

• Utilization limits — Set a maximum spend amount for a period. Choose a preset (daily, weekly, monthly, yearly, or collective) and provide the limit in cents.
• Transaction size limits — Set a minimum and/or maximum amount per individual transaction.

All amounts are specified in cents (e.g., $500.00 = 50000).

You can also check how much of a card's limit has been used with GET /card/{cardId}/utilization.

Restricting Where Cards Can Be Used

Within the same PATCH /card/{cardId} endpoint, you can restrict where a card is accepted:

• By merchant category code (MCC) — Allow or block specific merchant category codes.
• By merchant — Allow or block specific merchants by ID.
• By country — Allow or block transactions from specific countries using 2-digit country codes.

Each restriction uses an allowlist (only these are permitted) or blacklist (everything except these is permitted) approach.

Pausing, Unpausing, and Closing Cards

To change a card's status, use PATCH /card/{cardId} and set the status field:

• active — The card is live and can process transactions. Use this to unpause a paused card.
• paused — Temporarily disables the card. All transactions will be declined until you set it back to active.
• closed — Permanently closes the card. This cannot be undone.

Managing Card Groups

Card groups let you apply shared spending rules and restrictions to multiple cards at once. Instead of configuring limits on each card individually, you create a group with the rules you want and assign cards to it.

Create a group with POST /card-group, view it with GET /card-group/{cardGroupId}, and update its rules with PATCH /card-group/{cardGroupId}.

To add a card to a group, include the cardGroupId when creating the card (POST /card) or update an existing card (PATCH /card/{cardId}). To remove a card from a group, set cardGroupId to null.

Need More Help?

For the complete API reference with request and response examples, visit https://api.joinslash.com/openapi. For additional assistance, contact support through the dashboard or email support@joinslash.com.