For agencies
Your clients' outbound, your infrastructure
Stop paying per-seat for Instantly. Run every client through one API with team isolation, free warmup, and margins that actually work.
The agency cold email problem
Per-seat pricing kills margins
Instantly at $97/mo per client workspace. 20 clients = $1,940/mo just for the tool. Your margins disappear. zend.sh: one API key, unlimited clients. Pay per-email sent, not per-seat.
Manual warmup per client
Every new client means setting up warmup from scratch. 28 days before you can start sending. Clients get impatient. zend.sh: free warmup runs automatically. Connect inboxes, warmup starts. No manual setup.
No programmatic control
Dashboard tools don't integrate with your internal systems. Copy-pasting between tools. No automation. zend.sh: REST API + SDKs. Build your agency platform on top. Automate everything.
Built for agency economics
Per-email pricing, not per-seat
Pay $29/mo for 10,000 emails. Split across 10 clients = $2.90/client. Your margins stay healthy no matter how many clients you manage.
Team isolation via API keys
Each client gets their own API key with RLS isolation. Their data, mailboxes, and campaigns are completely separated. No cross-contamination.
Free warmup for every client
Every client inbox joins the P2P warmup network automatically. 28-day ramp with AI content, spam rescue, and engagement simulation. No extra cost.
White-label ready
The API doesn't expose zend.sh branding. Build your own dashboard, use your own domain, present it as your own infrastructure.
Health monitoring per client
Per-account health scores, blacklist monitoring, DNS checks. Know which client mailboxes need attention before they bounce.
Webhook-native
Every event fires a webhook — sent, replied, bounced, unsubscribed. Pipe into your CRM, Slack, or internal dashboard in real time.
Agency unit economics
Compare the cost of running 20 clients on Instantly vs zend.sh.
With Instantly
20 clients × $97/mo = $1,940/mo. Per-seat pricing scales linearly. Each client needs manual warmup setup. No API — manual campaign management. Your margin: whatever the client pays minus $97.
With zend.sh
Pro plan: $29/mo (10K emails). Scale plan: $79/mo (50K emails). Free warmup for every client inbox. API automation — no manual work. Your margin: whatever the client pays minus $1.50–$4/client.
Ready to build on infrastructure that scales?
Free warmup, 80+ API endpoints, full SDKs and CLI. Start sending in minutes.