Here are Singapore websites where you can buy (or rent/resell) sustainable clothing, grouped by type so it’s easy to browse:

Multi-brand marketplaces & big retailers with sustainability sections

• ZALORA — has an "Earth Edit" curation (sustainable materials, pre-loved, fair/eco production filters). (zalora.sg)
• The Green Collective — Singapore‑based curated eco marketplace (online + physical store). (thegreencollective.sg)
• Zerrin — local multi‑label boutique that curates emerging sustainable brands. (harpersbazaar.com.sg)

Recommerce / secondhand and rental platforms (circular options)

• REFASH (part of Carousell Group) — omnichannel secondhand fashion marketplace and stores in SG. (press.carousell.com)
• Carousell — large Singapore recommerce marketplace for preloved clothing (partners with Refash). (press.carousell.com)
• Style Theory — clothing subscription / rental service (women’s workwear/designer rental in SG). (styletheoryweb.co)

Homegrown sustainable brands (shopping direct from their websites)

• Esse — Singapore slow‑fashion label (natural fibres, B‑Corp, repair programs). (essethelabel.com)
• SOURCE Collections — basics made from Tencel/organic cotton with supply‑chain transparency. (sourcecollections.com)
• GRAYE Studio — seasonless pieces, repair/upcycle initiatives. (grayestudio.com)
• Studio Gypsied — batik + sustainable fabrics (Tencel/EcoVero) and handcrafted lines. (studiogypsied.com)
• Our Barehands — artisan‑led label focusing on small‑batch, ethically made pieces. (ourbarehands.com)
• Sui — slow‑fashion womenswear using organic/handwoven fabrics and low‑impact dyes. (sg.wearesui.com)
• Rock Daisy — functional pieces made from natural materials; Singapore label. (rockdaisyapparel.com)
• August Society — Singapore swimwear brand using recycled nylon (Econyl/recycled plastics). (augustsociety.com)

Other curated / niche marketplaces

• Orgayana (Wear marketplace) — lists sustainable, organic & vintage fashion options in SG. (orgayana.com)

Quick tips to shop more sustainably online

• Look for materials like Tencel/Lyocell, organic cotton, recycled polyester/ECONYL, or explicit “pre‑loved”/upcycled labels (ZALORA’s Earth Edit explains its criteria). (zalora.sg)
• Prefer brands that publish supply‑chain info, certifications (GOTS, OEKO‑TEX, GRS, Responsible Wool Standard, B‑Corp), or offer repair/upcycle programs (many homegrown labels do). (essethelabel.com