Short answer — the biggest places Singaporeans buy clothes online are:

• General marketplaces (wide selection & bargains): Shopee and Lazada — the two dominant e‑commerce platforms where you can buy everything from cheap fast‑fashion to branded items. (statista.com)
• Fashion‑focused retailers: ZALORA — the region’s main online fashion destination and go‑to for curated local + international brands. (corporate.zalora.com)
• Local/omnichannel brands: Singapore labels like Love, Bonito and homegrown chains such as Charles & Keith (plus big high‑street brands with local online stores like UNIQLO, Zara and H&M) — people buy directly from brand sites/apps for fit and returns. (lovebonito.com)
• Second‑hand / resale: Carousell (and specialist thrift players like Refash) — popular for preloved and sustainable shopping. (press.carousell.com)
• Discount/fast‑fashion entrants: Shein and Temu are widely browsed for very low‑cost fashion (many Singapore shoppers use them for bargains, though quality/returns can vary). (reuters.com)

Quick shopping tips:

• Check size guides and reviews (Asian sizing differs by brand).
• Watch big sales (11.11, 12.12, mid‑year) and app‑only promos for the best deals.
• Compare delivery times/return policies — brand sites and Zalora usually make returns easier than cross‑border marketplaces.

If you want, I can: list direct links to each site, recommend stores for a specific style or budget, or show which apps are best for bargains vs. reliable returns.