Slash API: Receiving Real-Time Webhook Notifications

Receiving Real-Time Webhook Notifications

Overview

Webhooks let you receive automatic notifications when events happen in your Slash account. Instead of polling the API for changes, Slash sends a request directly to your server whenever a card or transaction status changes.

Supported Event Types

• card.update: Triggered when a card's details or status changes
• card.delete: Triggered when a card is deleted
• card_creation.event: Triggered when a new card is created
• aggregated_transaction.create: Triggered when a new transaction is created
• aggregated_transaction.update: Triggered when a transaction status or details change

How Webhook Events Work

Webhook events contain metadata about what changed (entity ID, event type, event ID) but do not include the full entity data. To get the current state, fetch it from the corresponding GET endpoint using the entityId.

Setting Up Webhooks

Step 1: Create a Webhook Endpoint

POST https://api.slash.com/webhook

Provide: url, name, legalEntityId (optional)

Step 2: Verify Webhook Signatures

Every webhook request includes a slash-webhook-signature header. Verify this signature using Slash's public RSA key.

Step 3: Return a 2xx Response

Your endpoint must respond with a 2xx status code within 10 seconds.

Managing Webhook Endpoints

Listing Webhooks: GET https://api.slash.com/webhook

Updating Webhook Status: PATCH https://api.slash.com/webhook/{webhookId}

Available statuses: active, paused, archived

Viewing Notification History: GET https://api.slash.com/webhook/{webhookId}/notification

Webhook Retries and Backoff

Slash retries delivery up to 12 times with exponential backoff. After exhausting retries, your endpoint enters a backing-off state. After 6 consecutive permanent failures, the endpoint will be automatically disabled. Queued events are not lost.

Event Ordering and Idempotency

Slash cannot guarantee events are delivered in exact sequential order or only once. Use the eventId field as an idempotency key to detect and handle duplicate deliveries.

Authorization Webhooks (Enterprise)

Enterprise customers can configure authorization webhooks to approve or decline card transactions in real-time. Authorization webhooks have a 1.5-second timeout. Contact sales@slash.com to enable this feature.

Need More Help?

For help configuring webhooks or troubleshooting delivery issues, contact Slash support at support@joinslash.com.