Competitor Product Stock Availability Scraper Bot

Developing a Competitor Stock Availability Monitoring Bot

Monitoring competitor stock opens business opportunities: raise prices when competitors run out; signal managers about restocking; show "Limited Stock" when competitors are empty. The bot monitors availability on schedule and reacts to changes.

What Gets Tracked

• Availability/absence — is the product for sale
• Quantity — if site shows remaining stock ("3 left")
• Status — in stock / preorder / discontinued / temporarily unavailable
• Appearance dates — when product returned to sale

Stock Status Extractor

class StockStatusExtractor
{
    private array $inStockPatterns = ['/in\s*stock/i', '/available/i'];
    private array $outOfStockPatterns = ['/out\s*of\s*stock/i', '/unavailable/i', '/sold\s*out/i'];

    public function extract(string $html, array $config = []): StockStatus
    {
        $crawler = new Crawler($html);

        // Strategy 1: Microdata (most reliable)
        if ($availability = $this->extractFromMicrodata($crawler)) {
            return $availability;
        }

        // Strategy 2: JSON-LD
        if ($availability = $this->extractFromJsonLd($crawler)) {
            return $availability;
        }

        // Strategy 3: Custom CSS selectors from config
        if (!empty($config['stock_selector'])) {
            if ($availability = $this->extractWithSelector($crawler, $config)) {
                return $availability;
            }
        }

        // Strategy 4: Button state ("Buy" / "Add to Cart")
        return $this->extractFromButtonState($crawler);
    }

    public function extractQuantity(string $html): ?int
    {
        $crawler = new Crawler($html);
        $patterns = [
            '/(\d+)\s*(?:left|remaining)/i',
            '/in\s*stock[:\s]+(\d+)/i',
        ];

        $text = $crawler->text();
        foreach ($patterns as $pattern) {
            if (preg_match($pattern, $text, $m)) {
                return (int) $m[1];
            }
        }
        return null;
    }
}

Model and History

class CompetitorStock extends Model
{
    protected $casts = ['in_stock' => 'boolean'];

    protected static function booted(): void
    {
        static::updated(function (self $model) {
            if ($model->wasChanged('in_stock')) {
                CompetitorStockChanged::dispatch($model);
            }
        });
    }
}

Reacting to Changes

class HandleCompetitorStockChanged
{
    public function handle(CompetitorStockChanged $event): void
    {
        $stock = $event->stock;

        // Competitor ran out → notify about price opportunity
        if (!$stock->in_stock && $stock->getOriginal('in_stock')) {
            $this->notifyPriceOpportunity($stock->product, $stock->competitor);
        }

        // All competitors out of stock → apply scarcity pricing
        $allOutOfStock = CompetitorStock::where('product_id', $stock->product_id)
            ->where('in_stock', true)->doesntExist();

        if ($allOutOfStock && config('repricing.raise_when_competitors_out')) {
            $this->applyScarcityPricing($stock->product);
        }
    }
}

Development timeline: monitoring 3-5 competitors with history and events — 5-7 business days.