Licensing

Overview

SendyKit self-hosted uses EDD Software Licensing-powered license verification. Your license key determines your edition (Standard or Pro) and unlocks the corresponding features. Human checkout, licensing, and subscription mechanics run through Easy Digital Downloads on sendykit.dev.

How It Works

Purchase

Buy a license at sendykit.dev/pricing. You receive a license key: sk_lic_xxxxxxxxxxxxx

Install

curl -sSL https://install.sendykit.dev | bash

The installer prompts for your license key and validates it.

Validate

On first launch, the Go binary contacts the SendyKit licensing API to verify your key and download your entitlements (edition, features, metered service access).

Run

The binary caches your entitlements locally. Weekly heartbeat checks for updates. 30-day offline grace if the licensing server is unreachable.

Safety Guarantees

We take these seriously. SendyKit will never brick your installation.

Guarantee	What It Means
Fail-open	If the licensing server is down, your binary keeps running with cached entitlements. It never stops working.
30-day offline grace	After 30 days without a heartbeat: you see a warning banner. Not a shutdown. All features keep working.
No data exfiltration	Zero customer data leaves your server. No emails, subscriber lists, campaign content, API keys, or PII are ever transmitted.
Transparent logging	Every phone-home request is logged to `sendykit.log`. You can audit exactly what’s sent.
Auditable payload	The heartbeat sends only: `license_key`, `version`, `os`, `arch`, `subscriber_tier` (a range, not exact count), `uptime_days`. Nothing else.
Fully disable-able	Set `SENDYKIT_OFFLINE=true` to disable all phone-home. License cached indefinitely. No nag screens.
No kill switch	The binary never self-disables. Even with an expired or revoked license: warning banner only. All features keep working.
Open heartbeat spec	The heartbeat format is documented here so you can firewall-verify what’s transmitted.

Heartbeat Payload

{
  "license_key": "sk_lic_xxxxx",
  "version": "1.2.0",
  "os": "linux",
  "arch": "amd64",
  "subscriber_tier": "1k-5k",
  "feature_flags_hash": "a1b2c3d4",
  "uptime_days": 42
}

The subscriber_tier is a range bucket (e.g., “1k-5k”), not an exact count. We never know your actual subscriber count.

Editions

Feature	Standard	Pro
REST API (125 endpoints)	✅	✅
CLI (240+ commands)	✅	✅
Analytics Intelligence	✅	✅
Health Doctor (68 checks)	✅	✅
SMTP Overlay	✅	✅
Audit Trail	✅	✅
Admin UI (7 pages)	✅	✅
Visual Editor (GrapeJS)	✅	✅
AI Authoring	—	✅
Sequences & Funnels	—	✅
Automations	—	✅
Priority Support	—	✅
White Label	—	✅

Metered Add-Ons

Self-hosted customers can optionally purchase metered services that run through SendyKit’s infrastructure:

Service	What	Pricing
SMTP Pool Overflow	When your SES quota is exhausted, SendyKit routes overflow emails through our managed SMTP providers	$3-5/1000 emails
AI Content Credits	AI requests proxied through SendyKit’s API — no need for your own OpenAI/Anthropic key	$0.002/generation
Deliverability Shield	Continuous DNS/reputation monitoring from SendyKit’s servers	$49/year
Priority Support	Faster response times, dedicated support queue	$99/year

Usage is tracked natively by SendyKit. Human purchases and add-on checkout run through EDD on sendykit.dev, using the card attached to your customer account when applicable.

Offline Mode

For air-gapped or restricted environments:

.env

SENDYKIT_OFFLINE=true
SENDYKIT_LICENSE_KEY=sk_lic_xxxxxxxxxxxxx

In offline mode:

No network requests to SendyKit servers
License validated from local cache only
Metered add-ons (SMTP pool, AI credits) unavailable
All installed features work normally
No update notifications

Getting Started

Concepts

Self-Hosted

Billing

Features

Readiness

CLI

Overview

How It Works

Safety Guarantees

Heartbeat Payload

Editions

Metered Add-Ons

Offline Mode

​Overview

​How It Works

​Safety Guarantees

​Heartbeat Payload

​Editions

​Metered Add-Ons

​Offline Mode

Overview

How It Works

Safety Guarantees

Heartbeat Payload

Editions

Metered Add-Ons

Offline Mode