API v2 to v3 changes
Sent API v3 is the current major version. It replaces the v2 authentication scheme, wraps every response in a standard JSON envelope, and adds capabilities that v2 does not have. The v2 API remains available at /v2/ paths for existing integrations; the Legacy API reference documents it in full. For step-by-step upgrade instructions, see the API v2 to v3 migration guide.
Changes from v2
| Area | v2 | v3 | Details |
|---|---|---|---|
| Base path | /v2/ | /v3/ | |
| Authentication | x-sender-id and x-api-key headers | x-api-key header only | Authentication |
| Success responses | No standard envelope | Envelope with success, data, error, and meta | Data models |
| Error responses | FastEndpoints problem details | error object with prefixed code, message, details, and doc_url | Error handling |
| Property naming | camelCase (messageId) | snake_case (message_id) | |
| Sandbox mode | Not available | sandbox field in the request body | Sandbox mode |
| Idempotency | Not available | Idempotency-Key header on POST, PUT, and PATCH | Idempotency |
| Sender Profiles | Not available | Full CRUD at /v3/profiles | Sender Profiles |
| 10DLC brands and campaigns | Not available | Brand registration through Sender Profiles; campaigns at /v3/profiles/{profileId}/campaigns | |
| User management | Not available | Organization users at /v3/users | |
| Webhook management | Not available | /v3/webhooks, including secret rotation, delivery tests, status toggling, and event-type discovery | |
| Webhook event payloads | Flat payload | event field with a nested payload object | Webhook event types |
Version support
The v2 API is a legacy version: it remains supported, and Sent has not announced an end-of-support date. New integrations must use v3. The changelog records the release history for both versions.
Error Catalog
Every error code the Sent API v3 can return, with the HTTP status it maps to, the cause behind it, and the steps to resolve it
Rate Limits
Rate limit values, window semantics, 429 response headers, and per-endpoint limits for the Sent API v3, with the scope rules for shared account pools.