# BooleanSMTP Developers

> The developer reference for BooleanSMTP — hooks, wp-config.php constants, WP-CLI, the REST API and extension contracts, generated from the plugin itself.

## Start here

<CardGrid>
	<LinkCard
		title="Hooks"
		description="133 actions and filters, generated from the plugin's docblocks — signature, parameters and a working example for each."
		href="/hooks/"
	/>
	<LinkCard
		title="wp-config.php constants"
		description="Credentials per connection, the encryption key, debug switches — with a builder that writes the define() block for you."
		href="/constants/"
	/>
	<LinkCard
		title="WP-CLI"
		description="wp boolean-smtp queue:work, connections:list, logs:export, test-email and import."
		href="/wp-cli/"
	/>
	<LinkCard
		title="REST API"
		description="Every route under booleansmtp/v1, free and Pro, with its request and response shape."
		href="/rest-api/"
	/>
</CardGrid>

## What you can build

<CardGrid>
	<Card title="React to a send" icon="rocket">
		Hook into `boolean_smtp_email_sent`, `boolean_smtp_email_delivery_failed_final` and the rest of the delivery
		lifecycle — no polling, no parsing logs.
	</Card>
	<Card title="Change how mail is sent" icon="random">
		Filter the connection a message routes through, its headers, its body, or add a transport driver of your own.
	</Card>
	<Card title="Automate from the command line" icon="document">
		Every WP-CLI command and REST route is documented from the plugin's own argument definitions, kept in sync by a
		build check.
	</Card>
	<Card title="Explore visually" icon="warning">
		The [Hook Explorer](/hooks/explorer/) filters by kind, tier and area, and lights up the mail pipeline's hooks in
		the order they actually fire.
	</Card>
</CardGrid>

Setting up the plugin itself — installing it, connecting a mailer, reading the email log? That's
[docs.booleansmtp.com](https://docs.booleansmtp.com/), the site for people running BooleanSMTP rather than building on it.