InboxOS
Email infrastructure for developers

Send. Track.
Delight.

InboxOS is a Cloudflare-native transactional email API. Sub-50ms sends, DKIM/SPF/DMARC verified, open & click tracking built-in.

Start freeView docs

No credit card required · 500 emails/mo free forever

request
99.97%
Delivery Rate
<50ms
API Latency
200+
Edge PoPs
GDPR + SOC 2
Compliance
Features

Everything developers need.

One API to send, track, and manage transactional email at any scale — without stitching together five tools.

Edge Delivery

Runs on Cloudflare Workers. Your emails hit the nearest PoP in under 50ms — globally, every time.

Template Engine

Variables, conditionals, loops. Plus AI-powered template generation via Llama 3.1 — draft in seconds.

Domain Auth

Auto DKIM/SPF/DMARC verification and scoring. Get to inbox — not spam — from day one.

Open & Click Tracking

1×1 pixel + redirect tracking with real-time webhook events. Know exactly who engaged and when.

Smart Suppression

Auto-suppress bounces and complaints. RFC 8058 one-click unsubscribe handled for you, no code needed.

MCP + AI Agents

11 native Model Context Protocol tools for LLM orchestration. Let your AI agent send emails autonomously.

Quick start

Get started in 3 steps.

01

Create account

Sign up and get an API key in 60 seconds. No approval needed, no setup calls.

02

Verify your domain

Follow our built-in DKIM/SPF/DMARC guide. Copy-paste DNS records — we verify automatically.

03

Send emails

One POST request to /v1/send. That's it. Scale to millions with the same API.

API

The simplest email API.

One endpoint. Full power. Works with any language, framework, or runtime.

send-email.http
POST https://api.inboxos.dev/v1/send
Authorization: Bearer ik_live_your_api_key
Content-Type: application/json
{
"to": "alex@example.com",
"from": "hello@yourapp.com",
"subject": "Your invoice is ready",
"template": "invoice_ready",
"vars": {
"name": "Alex",
"invoice_id": "INV-2026-0042",
"amount": "$149.00",
"due_date": "2026-05-30"
},
"track_opens": true,
"track_clicks": true
}
Pricing

Simple, predictable pricing.

No per-seat pricing. No hidden fees. Pay for what you send.

Free
$0/mo

Perfect for side projects and testing.

  • 500 emails / month
  • 1 verified domain
  • Basic delivery analytics
  • DKIM/SPF/DMARC setup
  • API access
  • Community support
Start free
Most popular
Pro
$19/mo

For growing products that need reliability.

  • 25,000 emails / month
  • 10 verified domains
  • Open & click tracking
  • AI template generation
  • Contact lists & suppression
  • Webhooks & real-time events
  • Priority email support
Get started
Scale
$79/mo

For teams sending at serious volume.

  • 200,000 emails / month
  • Unlimited domains
  • Email scheduling
  • Advanced analytics & exports
  • MCP + AI agent tools
  • Dedicated IP (add-on)
  • Dedicated support
Get started

Start sending in 5 minutes.

Connect your domain, grab an API key, and ship your first transactional email before lunch.

No credit card required. 500 emails/mo free forever.