Amazon.in – exorbitant prices. Often 3 or 4 times. There are sellers who will send wrong products. Amazon will initiate a replacement which has little chance of happening if the price of item is low.

Calcuttaelectronics.com — very reliable, parts quality good. But since 2020 (after the first lockdown) their variety and stock has gone down and as of date of writing many parts are “out of stock” for many weeks. Good packaging. Support was a little disappointing.

Electroncomponents.com — has a good collection and very cheap. But the price and variety made me a bit curious (and cautious), so checked the internet and found they had a very bad reputation in the recent past. But still I ordered and got my items in time.
Parts quality mixed – some are of good quality some are cheap ones. Packaging okay. Delivery time is good.

Iotwebplanet.com — parts are good, delivery times is good, variety is good, but orders may get cancelled silently. Has COD facility. Good packaging.

Robomart.com — They are reliable. Collection is okay sort of.  Parts are often good but not always or some parts can be quite cheap quality. Packaging good.

Tanotis.com — this is in a different league from the rest including Amazon. Most parts which are not available in any other websites can be found here. Quality is very good. But the delivery time is long and sometimes order gets cancelled (but they do inform and give refund). Though costly but is still reasonable than other sites in that league. Very good packaging.
One word of advice, if available then go for COD always. I was planning to buy some parts from a website, they had a good collection and very reasonable price. I was slowly adding things to cart. But then suddenly one day I find the site has been shutdown by the owners. There was no prior notice. These are risky situations. With COD there will be peace of mind that the money will not be lost in case things goes bad.
And interestingly many of the websites selling electronics or iot parts in India have used domain privacy. When an e-commerce site (or any site where payment is involved) hides their contact details or domain details, it makes things a bit suspicious.

Kolkataonweb.com is not affiliated with any of the above websites, neither kolkataonweb.com endorses any of the above sites or guarantees their availability, product quality, reliability, pricing,  delivery and refund. The above is based on personal experiences and hence may vary.