Here is a list for best online rsources for UPSC Civil Services Examination:
- Mrunal.org : for Economics and Geography
- insightsonindia.com : for answer writing, test series and current affairs
- iasbaba.com : for answer writing, test series and current affairs
- byjus.com : current affairs and important articles
- iasscore.in : live online classes, test series and notes
- unacademy.com : lecture videos and expert guidance by Mr. Roman Saini, AIR-18, CSE-2013
- gktoday.in : great website for current affairs and important topics
- visionias.in : current affairs and one of the best test series
- forumias.com : forum discussion and like minded UPSC aspirants
PS: Of-course, there are many other websites and blogs available, but these websites are most helpful and have quality content followed by nearly all UPSC aspirants
IAS Toppers Blogs
- thesupermanreturns.wordpress.com : by Mr. Gaurav Agrawal, IAS AIR-1 CSE 2013
- rijubafna.com: by Ms. Riju Bafna, AIR-77, CSE 2013
- lohitmatani.wordpress.com : Lohit Matani, IPS
- irasinghal.blogspot.in by Ms. Ira Singhal, AIR-1, CSE 2014
Apart from the above-mentioned list of IAS online coaching websites (free and paid), it is advised to refer selected websites from Indian Government and NGOs as mentioned below.
- ncert.nic.in – Download NCERT Texts as PDF.
- nios.ac.in – Download NIOS Online Materials.
- egyankosh.ac.in – Download IGNOU Books.
- yojana.gov.in – Download Yojana and Kurukshetra Magazines.
- upsc.gov.in – Official Website of UPSC.
- pib.nic.in – Press Information Bureau Website, for government updates.
- prsindia.org – PRS Website for tracking bills in Parliament.
- idsa.in – IDSA website for Defense and Foreign relations.
- gatewayhouse.in – Indian Council for Global relations.
- envfor.nic.in – Ministry of Environment and Forests.
- mea.gov.in – Ministry of External Affairs.
- indiabudget.nic.in – Download Budget and Economic Survey.
- ptinews.com – Press Trust of India.
- pdgroup.upkar.in – Pratiyogita Darpan Magazine.
- ibef.org – India Brand Equity Foundation for economy and business.
- vikaspedia.in – Knowledge initiative by InDG.
Apart from the resources mentioned above, you can take guidance from IAS/IPS officers and other Civil servants on Quora.
Hope it helps.
Keep studying and all the best.
Courtesy : https://www.quora.com/What-is-the-process-to-study-online-for-the-IAS