Here are widely recognised, leading real-estate developers active in Kolkata (with a short note on each and sources you can check):

1. Ambuja Neotia — long-established Kolkata developer known for Ecospace, City Centre malls and mixed-use / eco-conscious projects. (ambujaneotia.com)
2. Merlin Group — major Kolkata developer behind large residential and commercial projects across the city and New Town. (merlinprojects.com)
3. South City Projects — Kolkata consortium famous for South City Mall and high‑profile residential developments (Altair, etc.). (southcityprojects.com)
4. Godrej Properties — national developer with large Kolkata township projects (e.g., Godrej Prakriti on B.T. Road). (godrejprakriti.in)
5. Salarpuria / Salarpuria Sattva Group — active in Kolkata (The 42 and other premium projects) with a strong regional presence. (salarpuriagroup.com)
6. PS Group (PS Srijan / PS Group family developers) — prominent in New Town and other Kolkata suburbs (projects like One10 / One110). (nexgenrealty.in)
7. Shriram Properties — known nationally and active in affordable / mid‑segment projects in and around Kolkata. (rivirtual.in)
8. Hiranandani / Hiranandani Communities — national luxury/residential developer with projects and presence in Kolkata/New Town. (rivirtual.in)
9. Mani Group / Diamond Group / Alcove Realty (consortium partners on The 42 and other landmark Kolkata projects). (en.wikipedia.org)
10. Merlin / Blackstone (investor activity) — while Merlin develops projects, large institutional investors (e.g., Blackstone) have recently taken major Kolkata assets—important for major transactions and the market outlook. (timesofindia.indiatimes.com)

Notes and how to use this:

• “Leading” can mean largest sales/land bank, most visible landmark projects, strongest local brand or most recent market activity — the list above blends those perspectives.
• If you’d like a tailored short‑list (for buying, investment yield, luxury vs affordable, or a specific suburb such as New Town, Rajarhat, Joka or Ballygunge), tell me which priority matters most and I’ll pull project-level details, recent launches and RERA registrations for those developers.