For developers
Build on top of
MailerSpark.
A real REST API. Signed webhooks. Bearer auth. Idempotent endpoints. The same MailerSpark your team uses, exposed as a stable, versioned API.
API v1 · Bearer auth · HMAC-SHA256 signed webhooks
REST API v1
Contacts, lists, campaigns. Create cold outreach sequences with step arrays.
Signed webhooks
20 event types. HMAC-SHA256 signatures. Delivery log + automatic retries.
API keys
Generate, revoke, scope. The full secret is only ever shown once.
SSRF + IDOR guards
Webhook URLs are SSRF-scanned. Every endpoint enforces org-scope.
Rate limits you can see
Redis-backed, per-key visibility in the dashboard. No mystery 429s.
Public subscribe API
No-auth /api/subscribe and /api/subscribe/confirm. Drop-in forms, JSON integrations.
curl -X POST https://app.mailerspark.com/api/v1/campaigns \
-H "Authorization: Bearer ms_live_***" \
-H "Content-Type: application/json" \
-d '{
"type": "cold",
"name": "Q1 Outbound",
"listId": "lst_8a3f",
"steps": [
{ "waitDays": 0, "subject": "Quick question about {{company}}" },
{ "waitDays": 3, "subject": "Re: Quick question" }
]
}'Get an API key
Sign up, generate a key, make a request.
Free plan includes API access from day one. Paid plans unlock higher rate limits and sequence-creation endpoints.