API overview - SendFlit

The SendFlit API is a JSON REST API over HTTPS.

Item	Value
Base URL	`https://api.sendflit.com/v1`
Current version	v1 (initial release, see the changelog)
Format	JSON request and response bodies, UTF-8
Authentication	`Authorization: Bearer re_...` on every request except the health check
Health check	`GET https://api.sendflit.com/health`, returns `{"status":"ok","service":"sendflit","version":"1.0.0"}`

Versioning

The version is part of the URL path. v1 is the current stable version. Within v1 we add new endpoints and optional fields without breaking existing integrations. Any breaking change ships under a new path version, and v1 keeps working while you migrate. The version field in the health response reports the build of the service, so it can change between deployments even within v1.

Authentication

Send your API key as a bearer token. Each key has a scope that limits what it can do:

Scope	Can do
`full`	Everything, including key and domain management.
`sending`	Send email and read its delivery status.
`read`	Read-only. Cannot send.

A request with a missing, invalid or revoked key returns 401. A request with a valid key that lacks the scope for the action returns 403. See Security.

Endpoints

Emails

Method	Path	Purpose
`POST`	`/v1/email`	Send one email. Supports `Idempotency-Key`.
`POST`	`/v1/emails/batch`	Send up to 100 emails. Supports `Idempotency-Key`. Returns a result per message.
`GET`	`/v1/emails`	List emails.
`GET`	`/v1/emails/{id}`	Get one email and its delivery status.
`DELETE`	`/v1/emails/{id}`	Cancel a scheduled email before it sends.

Domains

Method	Path	Purpose
`POST`	`/v1/domains`	Register a sending domain. Returns the DNS records to publish.
`GET`	`/v1/domains`	List domains.
`PUT`	`/v1/domains/{id}`	Update a domain.
`GET`	`/v1/domains/{id}/records`	The DNS records to publish for a domain.
`GET`	`/v1/domains/{id}/deliverability`	Deliverability status for a domain.
`POST`	`/v1/domains/{id}/verify`	Check the DNS records and verify the domain.

Keys, webhooks and usage

Method	Path	Purpose
`DELETE`	`/v1/keys/{id}`	Revoke an API key immediately.
`GET`	`/v1/usage`	Current usage against your plan’s quotas.

Webhook endpoints are managed in the dashboard. Events are delivered as described in Webhooks.

Conventions

Errors are JSON with a detail field. See Errors, retries and limits.
Idempotency: send an Idempotency-Key header with send and batch requests so a retry never sends twice.
Timestamps are ISO 8601 in UTC, for example 2026-09-01T09:00:00Z.
Rate limits apply per API key, per second, and depend on your plan. Daily and monthly quotas apply per account.

​Versioning

​Authentication

​Endpoints

​Emails

​Domains

​Keys, webhooks and usage

​Conventions