All the methods mentioned down below are absolutely free.
1.EARN FROM PTC SITES
PTC stands for paid to click sites, these websites pay you for clicking their sponsored client's advertisement.
The amount of time you have to contribute may vary from 5 sec to 30 sec for watching an advertisement. As the time you contribute increases the amount you will get paid increases. This is the best method to some extra money with minimum time devotion. That is why this method is best suitable for teenagers or college students.
HERE is my pick of legit PTC sites helps you to earn some extra pennies.
2.EARN WITH GPT SITES
Get paid to (GPT) sites pay you for watching videos, Playing games, Completing small surveys etc.
These websites can also help you to earn money from your smartphone. Most of the GPT sites support a web browsing.
HERE are five legit GPT sites which I personally use.
3.BECOME A CAPTCHA SOLVER
The above two mentioned way has the limited amount of opportunity per day i.e only a particular amount of tasks or advertisements are provided to the user in a day. But in this method, the amount you earn depends upon the work you completed.
If you are interested in this you should definitely check out this list of 5 BEST CAPTCHA ENTRY SITES.
4.EARN WITH AFFILIATE MARKETING
There are hundreds of online merchants like Flipkart, Amazon, eBay, Clickbank, CJ etc where one can signup and promote their products or services to get paid.
I would suggest that before trying your luck in this sector of online earning, one must learn some basics or fundamentals about affiliate marketing.
5.ADSENSE- A Google Service
The most effective way to earn online money. Adsense is a service provided by Google. Adsense provides you with an advertisement for your platform and get paid for promoting advertisements through your platform. This platform might be your website or a youtube channel.
I mentioned this method in the last because my experience says that this method is not as easy as other above-mentioned methods. But this is the most stable, convenient and trustworthy method to earn online.
***NOTE: - There are much more ways to earn online, But these are my picks from my experience especially for teenagers or college students who couldn't afford much time on these sites.