Slack API for PHP

Lightweight PHP wrapper for Slack Web API. Zero dependencies.

Send messages, blocks, and attachments to channels. Incoming webhooks and slash command verification with HMAC-SHA256.

Author: Renzo Johnson

Requirements

• PHP 8.4+
• ext-curl
• ext-json

Installation

composer require renzojohnson/slack-api

Quick Start

use RenzoJohnson\Slack\Slack;

$slack = new Slack('xoxb-your-bot-token');

// Send a text message
$slack->sendText('#general', 'Hello from PHP!');

Web API Methods

Send Text

$slack->sendText('#general', 'Hello World');

// Thread reply
$slack->sendText('#general', 'Replying...', threadTs: '1234567890.123456');

Send Blocks (Block Kit)

use RenzoJohnson\Slack\Message\Block;

$slack->sendBlocks('#alerts', [
    Block::header('Deploy Alert'),
    Block::divider(),
    Block::section('Production deploy completed for *v2.1.0*'),
    Block::image('https://example.com/chart.png', 'CPU chart'),
], text: 'Deploy Alert — fallback for notifications');

Send Attachment (Legacy)

$slack->sendAttachment(
    '#ops',
    fallback: 'Server CPU at 95%',
    color: '#ff0000',
    title: 'Server Alert',
    text: 'CPU usage has exceeded threshold.',
    fields: [
        ['title' => 'Server', 'value' => 'web-01', 'short' => true],
        ['title' => 'CPU', 'value' => '95%', 'short' => true],
    ],
);

Update Message

$response = $slack->sendText('#general', 'Loading...');
$ts = $response['ts'];

$slack->updateMessage('#general', $ts, 'Done!');

Delete Message

$slack->deleteMessage('#general', '1234567890.123456');

Add Reaction

$slack->addReaction('#general', '1234567890.123456', 'thumbsup');

List Conversations

$channels = $slack->listConversations();

Auth Test

$info = $slack->authTest();
echo $info['user']; // bot username

Incoming Webhooks

No bot token needed — just a webhook URL.

use RenzoJohnson\Slack\Webhook\IncomingWebhook;

$webhook = new IncomingWebhook('https://hooks.slack.com/services/T.../B.../xxx');

// Simple text
$webhook->send('Deploy complete!');

// Rich message
use RenzoJohnson\Slack\Message\WebhookMessage;

$webhook->send(new WebhookMessage(
    'Deploy complete!',
    username: 'DeployBot',
    iconEmoji: ':rocket:',
));

Slash Commands

Verify and Parse

use RenzoJohnson\Slack\Webhook\SlashCommand;

// Verifies X-Slack-Signature via HMAC-SHA256, returns parsed params
$params = SlashCommand::verify('your-signing-secret');

echo $params['command'];    // /weather
echo $params['text'];       // 94070
echo $params['user_name'];  // john

Respond

// Ephemeral (only visible to user)
SlashCommand::respond('Processing your request...');

// Visible to entire channel
SlashCommand::respond('Weather: 72F, Sunny', inChannel: true);

Error Handling

use RenzoJohnson\Slack\Exception\AuthenticationException;
use RenzoJohnson\Slack\Exception\RateLimitException;
use RenzoJohnson\Slack\Exception\SlackException;

try {
    $slack->sendText('#general', 'Hello');
} catch (AuthenticationException $e) {
    // Invalid bot token
} catch (RateLimitException $e) {
    $retryAfter = $e->getRetryAfter(); // seconds
} catch (SlackException $e) {
    // Other API errors (channel_not_found, etc.)
    $errorData = $e->getErrorData();
}

Testing

composer install
vendor/bin/phpunit

Links

• Packagist
• GitHub
• Issues
• Author

License

MIT License. Copyright (c) 2026 Renzo Johnson.