InboxKit
Email inboxes,
designed for agents.
curl -X POST https://api.inboxkit.dev/v1/inboxes \
-H "Authorization: Bearer $INBOXKIT_API_KEY"→ [email protected] is live. No DNS.
Agents can browse, write code, and call any API. But the world still runs on email — sign-ups, invoices, support, introductions. InboxKit gives every agent a real address, so it can take part.
One inbox. Every way in and out.
Create an address once. New mail reaches your agent the way it prefers, and replies land back in the same thread.
const res = await fetch("https://api.inboxkit.dev/v1/inboxes", { method: "POST", headers: { Authorization: `Bearer ${key}` }, body: JSON.stringify({ local_part: "support" }),});// [email protected] — reachable four waysWatch an agent handle its mail.
Create, receive, get pushed, reply. The whole loop is plain HTTP.
Three calls to a working agent inbox.
Plain REST and JSON. Use it from any language, any framework, any agent runtime.
1const res = await fetch("https://api.inboxkit.dev/v1/inboxes", {2 method: "POST",3 headers: {4 Authorization: `Bearer ${process.env.INBOXKIT_API_KEY}`,5 "Content-Type": "application/json",6 },7 body: JSON.stringify({ local_part: "support" }),8});9 10const { address } = await res.json();{ "org_id": 42, "address": "[email protected]", "mode": "instant", "inbox": { "id": 118, ... }}Not AI for your email.
Email for your AI.
Everything an agent needs to own an address, hold a conversation, and act on what arrives.
Inboxes on demand
One inbox per agent, per user, or per task. Each gets its own address and history on your hosted domain.
Your own domain
Start on inboxkit.dev, then move to your domain. We return the DNS records — or set them for you with Domain Connect.
Full MIME + attachments
The raw message, parsed text and HTML, and every attachment. Send attachments back the same way.
Extraction built in
Pull structured fields from a message or interpret an attachment with one call. Your agent acts, not parses.
Push, not polling
Signed webhooks for your backend, a WebSocket for long-running agents. Filter by inbox, test with a sample event.
Scoped by design
Keys belong to an organization. Inboxes, events, and sockets never cross that line.
What agents do with an inbox.
Anything a person does with email, an agent can now do too — without borrowing someone's account.
A small API you can hold in your head.
Bearer-token auth, predictable resources, JSON in and out. Your agent — or your coding assistant — learns it in one read.
Simple plans. Scale when you do.
For one agent in production.
- 14-day trial
- 1,000 sends / month
- 10,000 receives / month
- 10 inboxes
- Email support
For a fleet of agents on your domain.
- 25,000 sends / month
- 100,000 receives / month
- 100 inboxes
- Custom domains
- Priority support
For platforms that give every user an inbox.
- Unlimited sends
- Unlimited receives
- Unlimited inboxes
- Dedicated support
- Custom SLA
Questions,
answered.
The short version of how InboxKit works. Something missing? Ask us when you request access.
No. Every account gets a hosted inboxkit.dev domain, so your first inbox works in one API call. Add your own domain when you are ready — we give you the DNS records, or set them for you with Domain Connect.
Register a destination for message.received, or hold a WebSocket open at /v1/ws. Each push carries an X-InboxKit-Signature header (HMAC-SHA256), so you can verify it came from us.
Yes. POST /v1/inboxes/:address/send sends a new message with text, HTML, and attachments. Replies go through /messages/:id/reply so they stay in the thread.
Yes. Replies set In-Reply-To and References headers, so mail clients group them with the original message.
Yes. You get the full MIME message and every attachment. There are also endpoints to extract structured data from a message and to interpret an attachment.
Not today. The API is plain REST and JSON with a Bearer key, so any HTTP client works — fetch, requests, or curl.
InboxKit is in private beta. We onboard teams in small batches so that deliverability stays high for every sender on the platform.
Give your agent
an address.
Tell us what you are building. We will get you set up.