- var_dump: documentation ( source)
- json_decode: documentation ( source)
<?php
$json = '{"outfits": [{"1": [{"category_id": "women_jeans", "product_id": 464540467}, {"category_id": "women_tops", "product_id": 487351815}, {"category_id": "women_coats", "product_id": 493322686}, {"category_id": "women_bags", "product_id": 483902882}, {"category_id": "women_shoes", "product_id": 492772225}]}]}';
$outfits = json_decode($json);
var_dump($outfits->outfits[0]->category_id);